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IntroductionLM2596seriesisa3.0Astep-downswitchingregulatorchipproducedbyTexasInstruments(TI).Itcontainsafixedfrequencyoscillator(150KHZ)andareferencevoltageregulator(1.23v),andhasperfectprotectioncircuit,currentlimit,thermalshutdowncircuit,etc.LM2596isacommonvoltageregulatorchip,soitspopularapplicationonthemarketisLM2596buckconvertermodule.ThisvediointroducesLM2596buckconvertermoduleCatalogIntroductionDocumentandMediaLM2596PinConfigurationandFunctionsTypicalApplicationCircuitsBasicParametersHowtousetheLM2596RegulatorCADandCAESymbolsAdvantagesFeaturesApplicationsAlternativeModelsHeatsinkforLM2596ProductManufacturerProductRangeFAQOrdering&QuantityDocumentandMediaDatasheetsLM2596LM2596PinConfigurationandFunctionsThedatasheetoflm2596providedaboveisforyourreference,sothatyoucanunderstandthephysicaldimensionsofallpackagesinmoredetail.Theconfigurationofall5pinsandthefunctionofeachpinareasfollows:Thefunctionofall5pinsofLM324stepdownswitchingregulatorareasfollows:PinNumberPinNameDescription1VINThisisthepositiveinputpoweroftheICswitchingregulator.Theremustbeasuitableinputbypasscapacitoronthispintominimizevoltagetransientsandtosupplytheswitchingcurrentsrequiredbytheregulator.2OutputThispinisaninternalswitch.Thevoltageonthispinisswitchedbetweenapproximately(+VIN-VSAT)andapproximately-0.5V,andthedutycycleisVOUT/VIN.Inordertominimizecouplingwithsensitivecircuits,thecopperareaofthePCBconnectedtothispinmustbekepttoaminimum.3GroundCircuitground4FeedBackSensestheregulatedoutputvoltagetocompletethefeedbackloop5ON/OFFEnablepin,shouldbegroundedfornormaloperationTypicalApplicationCircuitsFixedOutputSeriesBuckRegulatorAdjustableOutputSeriesBuckRegulatorBasicParametersVin(Min)4.5VVin(Max)40VVout(Min)3.3VVout(Max)37VIout(Max)3AIq(Typ)5mASwitchingfrequency(Min)110kHzSwitchingfrequency(Max)173kHzFeaturesEnable,OverCurrentProtectionOperatingtemperaturerange-40℃to125℃RatingCatalogApprox.price1ku|1.8US$Regulatedoutputs1HowtousetheLM2596RegulatorItisquiteeasytouseLM2596,becauseitrequiresveryfewcomponents.Theunregulatedvoltageisprovidedtopin1(Vin)throughthefiltercapacitortoreduceinputnoise.TheON/OFForenablepin(pin5)shouldbegroundedtoenabletheIC.Ifsettohighlevel,ICwillentershutdownmodeandpreventleakagecurrent.Thisfunctionisveryusefulforsavinginputpowerwhenworkingonbattery.Thefeedbackpinisanimportantpinforsettingtheoutputvoltage.Itdetectstheoutputvoltageandadjuststheswitchingfrequencyoftheinternalswitchaccordingtothevalueoftheoutputvoltagetoprovidetherequiredoutputvoltage.Finally,theoutputvoltageisobtainedthroughpin2throughtheLCfilter.Thecompletecircuitdiagramisshownbelow,andyoucanusuallyfindthesecircuitsintheLM2596DCconvertermodule.CADandCAESymbolsPackagePinsDownload(NEB)5ViewoptionsDDPAK/TO-263(KTT)5ViewoptionsTO-220(NDH)5ViewoptionsAdvantagesTheLM2596seriesregulatorisamonolithicintegratedcircuitwithallthefunctionsofastep-downswitchingregulator,capableofdrivinga3Aloadthroughexcellentlineandloadregulation.Thesedevicesprovidefixedoutputvoltagesof3.3V,5V,and12V.Theseregulatorsrequireaminimumnumberofexternalcomponents,areeasytouse,andhaveinternalfrequencycompensationandafixedfrequencyoscillator.TheLM2596seriesoperatesataswitchingfrequencyof150kHzandrequiresfewerfiltercomponentsthanlow-frequencyswitchingregulators.Availableinastandard5-pinTO-220packagewithseveraldifferentleadbendoptions,anda5-pinTO-263surfacemountpackage.Features3.3-V,5-V,12-V,andadjustableoutputversionsAdjustableversionoutputvoltagerange:1.2-Vto37-V4%maximumoverlineandloadconditionsAvailableinTO-220andTO-263packages3.0AoutputloadcurrentInputvoltagerangeupto40VRequiresonlyfourexternalcomponentsExcellentlineandloadregulationspecifications150-kHzFixed-frequencyinternaloscillatorTTLshutdowncapabilityLowpowerstandbymode,IQ,typically80AHighefficiencyUsesreadilyavailablestandardinductorsThermalshutdownandcurrent-limitprotectionApplicationsGridinfrastructureEPOSHometheaterAlternativeModelsLM2576BD9876ACT4523Forhighvoltageinput:HVversioncanbeselected,suchasLM2576HVT,LM2576HVS,thehighestinputvoltagecanreach60V;HeatsinkforLM2596LM2596hastwotypesofpackages:TO-220(T);TO-263(S).Generally,theLM2596intheTO-220(T)packageneedstobeequippedwithaheatsink.Thesizeoftheheatsinkisdeterminedbytheinputvoltage,outputvoltage,loadcurrentandambienttemperature.Thehighertheambienttemperature,thehighertheneedforheatdissipation.TheLM2596intheTO-263(S)packageisasurfacemountcomponenttobesolderedonthePCBboard.CopperandPCBboardcontributetotheheatdissipationofthispackageddevice,suchasfreewheelingdiodesandinductors.ThecopperareaonthePCBforsolderingthispackageddevicemustbeatleast0.4squareinches.Morecopperareawillimprovethethermalcharacteristics,butwhenitislargerthan6squareinches,theimprovementinheatdissipationisverysmall,soventilationinthecaseofuse.ProductManufacturerTexasInstrumentsInc.(TI)isanAmericantechnologycompanythatdesignsandmanufacturessemiconductorsandvariousintegratedcircuits,whichitsellstoelectronicsdesignersandmanufacturersglobally.ItsheadquartersareinDallas,Texas,UnitedStates.TIisoneofthetoptensemiconductorcompaniesworldwide,basedonsalesvolume.TexasInstrumentssfocusisondevelopinganalogchipsandembeddedprocessors,whichaccountsformorethan80%oftheirrevenue.TIalsoproducesTIdigitallightprocessing(DLP)technologyandeducationtechnologyproductsincludingcalculators,microcontrollersandmulti-coreprocessors.Todate,TIhasmorethan43,000patentsworldwide.ProductRangeDevicesBoardsDeveloperToolsARMPROCESSORSAUTOMOTIVEPRODUCTSIDENTIFICATIONSECURITYKinetisCortex-MMicrocontrollersIn-VehicleNetworkNFCLPCCortex-MMicrocontrollersMicrocontrollersandProcessorsRFIDFAQWhatislm2596?TheLM2596seriesofregulatorsaremonolithicintegratedcircuitsthatprovidealltheactivefunctionsforastep-down(buck)switchingregulator,capableofdrivinga3-Aloadwithexcellentlineandloadregulation.WhatisthedifferencebetweenLM2596andLM2595?LM2596:Thehighestoutputcurrentis3A,1PIN-VOUT,2PIN-VIN;LM2595:Thehighestoutputcurrentis1A,1PIN-VIN,2PIN-VOUT.WhatisthevoltageofeachpinofLM2596-12?Whatisthefunctionofeachpin?Pin1istheinputterminal,12V,thenormalworkingvoltagerangeshouldbe14V~37Vundertheoutputcondition;pin2istheoutputterminal,hereisthehigh-frequencyoscillationoutput,notDCvoltage,sothereisnodefinitevoltage;pin3isgrounded,0V;Pin5istheenablecontrolterminal,LM2596worksnormallywhenconnectedtoalowlevel,andnooutputisturnedoffwhenconnectedtoahighlevel,usuallydirectlygrounded;Pin4isthefeedbackcontrolsignalinputterminal,connectedtothemiddleconnectionpointoftheproportionalresistor,wherethevoltageItisproportionaltotheactualoutput.CanLM2596outputnegativevoltage?LM2596canoutputnegativevoltage.LM2596hasdifferentapplicationcircuits,whichcanoutputpositivevoltageornegativevoltage,butithasnoboostfunction,andtheabsolutevalueofitsoutputvoltagemustbelessthantheabsolutevalueoftheinputvoltage.Inthecircuitwithadjustableoutputvoltageoflm2596,cantheoutputvoltagebegreaterthantheinputvoltage?TheLM2596switchingvoltageregulatorisastep-downpowermanagementmonolithicintegratedcircuit,whichcanoutput3Adrivecurrentandhasgoodlinearityandloadregulationcharacteristics.Theoutputvoltagewillnotbegreaterthantheinputvoltage.Iftheoutputvoltageisgreaterthantheinputvoltage,itisbesttouseastep-uppowerchip.SuchasXL6009,VT1050.Afterreadingtheblog,haveyoubetterunderstandLM2596?Finally,ifyouhaveanyquestionsaboutLM2596,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!

IntroductionLM2596seriesisa3.0Astep-downswitchingregulatorchipproducedbyTexasInstruments(TI).Itcontainsafixedfrequencyoscillator(150KHZ)andareferencevoltageregulator(1.23v),andhasperfectprotectioncircuit,currentlimit,thermalshutdowncircuit,etc.LM2596isacommonvoltageregulatorchip,soitspopularapplicationonthemarketisLM2596buckconvertermodule.ThisvediointroducesLM2596buckconvertermoduleCatalogIntroductionDocumentandMediaLM2596PinConfigurationandFunctionsTypicalApplicationCircuitsBasicParametersHowtousetheLM2596RegulatorCADandCAESymbolsAdvantagesFeaturesApplicationsAlternativeModelsHeatsinkforLM2596ProductManufacturerProductRangeFAQOrdering&QuantityDocumentandMediaDatasheetsLM2596LM2596PinConfigurationandFunctionsThedatasheetoflm2596providedaboveisforyourreference,sothatyoucanunderstandthephysicaldimensionsofallpackagesinmoredetail.Theconfigurationofall5pinsandthefunctionofeachpinareasfollows:Thefunctionofall5pinsofLM324stepdownswitchingregulatorareasfollows:PinNumberPinNameDescription1VINThisisthepositiveinputpoweroftheICswitchingregulator.Theremustbeasuitableinputbypasscapacitoronthispintominimizevoltagetransientsandtosupplytheswitchingcurrentsrequiredbytheregulator.2OutputThispinisaninternalswitch.Thevoltageonthispinisswitchedbetweenapproximately(+VIN-VSAT)andapproximately-0.5V,andthedutycycleisVOUT/VIN.Inordertominimizecouplingwithsensitivecircuits,thecopperareaofthePCBconnectedtothispinmustbekepttoaminimum.3GroundCircuitground4FeedBackSensestheregulatedoutputvoltagetocompletethefeedbackloop5ON/OFFEnablepin,shouldbegroundedfornormaloperationTypicalApplicationCircuitsFixedOutputSeriesBuckRegulatorAdjustableOutputSeriesBuckRegulatorBasicParametersVin(Min)4.5VVin(Max)40VVout(Min)3.3VVout(Max)37VIout(Max)3AIq(Typ)5mASwitchingfrequency(Min)110kHzSwitchingfrequency(Max)173kHzFeaturesEnable,OverCurrentProtectionOperatingtemperaturerange-40℃to125℃RatingCatalogApprox.price1ku|1.8US$Regulatedoutputs1HowtousetheLM2596RegulatorItisquiteeasytouseLM2596,becauseitrequiresveryfewcomponents.Theunregulatedvoltageisprovidedtopin1(Vin)throughthefiltercapacitortoreduceinputnoise.TheON/OFForenablepin(pin5)shouldbegroundedtoenabletheIC.Ifsettohighlevel,ICwillentershutdownmodeandpreventleakagecurrent.Thisfunctionisveryusefulforsavinginputpowerwhenworkingonbattery.Thefeedbackpinisanimportantpinforsettingtheoutputvoltage.Itdetectstheoutputvoltageandadjuststheswitchingfrequencyoftheinternalswitchaccordingtothevalueoftheoutputvoltagetoprovidetherequiredoutputvoltage.Finally,theoutputvoltageisobtainedthroughpin2throughtheLCfilter.Thecompletecircuitdiagramisshownbelow,andyoucanusuallyfindthesecircuitsintheLM2596DCconvertermodule.CADandCAESymbolsPackagePinsDownload(NEB)5ViewoptionsDDPAK/TO-263(KTT)5ViewoptionsTO-220(NDH)5ViewoptionsAdvantagesTheLM2596seriesregulatorisamonolithicintegratedcircuitwithallthefunctionsofastep-downswitchingregulator,capableofdrivinga3Aloadthroughexcellentlineandloadregulation.Thesedevicesprovidefixedoutputvoltagesof3.3V,5V,and12V.Theseregulatorsrequireaminimumnumberofexternalcomponents,areeasytouse,andhaveinternalfrequencycompensationandafixedfrequencyoscillator.TheLM2596seriesoperatesataswitchingfrequencyof150kHzandrequiresfewerfiltercomponentsthanlow-frequencyswitchingregulators.Availableinastandard5-pinTO-220packagewithseveraldifferentleadbendoptions,anda5-pinTO-263surfacemountpackage.Features3.3-V,5-V,12-V,andadjustableoutputversionsAdjustableversionoutputvoltagerange:1.2-Vto37-V4%maximumoverlineandloadconditionsAvailableinTO-220andTO-263packages3.0AoutputloadcurrentInputvoltagerangeupto40VRequiresonlyfourexternalcomponentsExcellentlineandloadregulationspecifications150-kHzFixed-frequencyinternaloscillatorTTLshutdowncapabilityLowpowerstandbymode,IQ,typically80AHighefficiencyUsesreadilyavailablestandardinductorsThermalshutdownandcurrent-limitprotectionApplicationsGridinfrastructureEPOSHometheaterAlternativeModelsLM2576BD9876ACT4523Forhighvoltageinput:HVversioncanbeselected,suchasLM2576HVT,LM2576HVS,thehighestinputvoltagecanreach60V;HeatsinkforLM2596LM2596hastwotypesofpackages:TO-220(T);TO-263(S).Generally,theLM2596intheTO-220(T)packageneedstobeequippedwithaheatsink.Thesizeoftheheatsinkisdeterminedbytheinputvoltage,outputvoltage,loadcurrentandambienttemperature.Thehighertheambienttemperature,thehighertheneedforheatdissipation.TheLM2596intheTO-263(S)packageisasurfacemountcomponenttobesolderedonthePCBboard.CopperandPCBboardcontributetotheheatdissipationofthispackageddevice,suchasfreewheelingdiodesandinductors.ThecopperareaonthePCBforsolderingthispackageddevicemustbeatleast0.4squareinches.Morecopperareawillimprovethethermalcharacteristics,butwhenitislargerthan6squareinches,theimprovementinheatdissipationisverysmall,soventilationinthecaseofuse.ProductManufacturerTexasInstrumentsInc.(TI)isanAmericantechnologycompanythatdesignsandmanufacturessemiconductorsandvariousintegratedcircuits,whichitsellstoelectronicsdesignersandmanufacturersglobally.ItsheadquartersareinDallas,Texas,UnitedStates.TIisoneofthetoptensemiconductorcompaniesworldwide,basedonsalesvolume.TexasInstrumentssfocusisondevelopinganalogchipsandembeddedprocessors,whichaccountsformorethan80%oftheirrevenue.TIalsoproducesTIdigitallightprocessing(DLP)technologyandeducationtechnologyproductsincludingcalculators,microcontrollersandmulti-coreprocessors.Todate,TIhasmorethan43,000patentsworldwide.ProductRangeDevicesBoardsDeveloperToolsARMPROCESSORSAUTOMOTIVEPRODUCTSIDENTIFICATIONSECURITYKinetisCortex-MMicrocontrollersIn-VehicleNetworkNFCLPCCortex-MMicrocontrollersMicrocontrollersandProcessorsRFIDFAQWhatislm2596?TheLM2596seriesofregulatorsaremonolithicintegratedcircuitsthatprovidealltheactivefunctionsforastep-down(buck)switchingregulator,capableofdrivinga3-Aloadwithexcellentlineandloadregulation.WhatisthedifferencebetweenLM2596andLM2595?LM2596:Thehighestoutputcurrentis3A,1PIN-VOUT,2PIN-VIN;LM2595:Thehighestoutputcurrentis1A,1PIN-VIN,2PIN-VOUT.WhatisthevoltageofeachpinofLM2596-12?Whatisthefunctionofeachpin?Pin1istheinputterminal,12V,thenormalworkingvoltagerangeshouldbe14V~37Vundertheoutputcondition;pin2istheoutputterminal,hereisthehigh-frequencyoscillationoutput,notDCvoltage,sothereisnodefinitevoltage;pin3isgrounded,0V;Pin5istheenablecontrolterminal,LM2596worksnormallywhenconnectedtoalowlevel,andnooutputisturnedoffwhenconnectedtoahighlevel,usuallydirectlygrounded;Pin4isthefeedbackcontrolsignalinputterminal,connectedtothemiddleconnectionpointoftheproportionalresistor,wherethevoltageItisproportionaltotheactualoutput.CanLM2596outputnegativevoltage?LM2596canoutputnegativevoltage.LM2596hasdifferentapplicationcircuits,whichcanoutputpositivevoltageornegativevoltage,butithasnoboostfunction,andtheabsolutevalueofitsoutputvoltagemustbelessthantheabsolutevalueoftheinputvoltage.Inthecircuitwithadjustableoutputvoltageoflm2596,cantheoutputvoltagebegreaterthantheinputvoltage?TheLM2596switchingvoltageregulatorisastep-downpowermanagementmonolithicintegratedcircuit,whichcanoutput3Adrivecurrentandhasgoodlinearityandloadregulationcharacteristics.Theoutputvoltagewillnotbegreaterthantheinputvoltage.Iftheoutputvoltageisgreaterthantheinputvoltage,itisbesttouseastep-uppowerchip.SuchasXL6009,VT1050.Afterreadingtheblog,haveyoubetterunderstandLM2596?Finally,ifyouhaveanyquestionsaboutLM2596,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!

FAQWhatisl293d?L293DICisadualH-bridgemotordriverIC.OneH-bridgeiscapabletodriveadcmotorinbidirectional.L293DICisacurrentenhancingICastheoutputfromthesensorisnotabletodrivemotorsitselfsoL293Disusedforthispurpose.Whichisbetterl293dvsl298n?L293DDriversOperatesat4.5Vto36VwhereasL298NcanbeOperatesatupto46V.Maximum600mACurrentcanbedrawnthroughbothchannelsofL293DwhereasL298NMotorDrivercandrawupto2Afrombothchannels.WhatistheuseofEnablepininl293d?L293DhasanenablefacilitywhichhelpsyouenabletheICoutputpins.Ifanenablepinissettologichigh,thenstateoftheinputsmatchthestateoftheoutputs.Ifyoupullthislow,thentheoutputswillbeturnedoffregardlessoftheinputstates.HowmanyDCmotorscanbecontrolledbyanICl293d?TheL293Disa16-pinMotorDriverICwhichcancontroluptotwoDCmotorssimultaneously,inanydirection.HowdoIconnectmyArduinotol293d?Connect5VtoEnable1,Vss,andVsontheL293D.Connectdigitaloutputpins(wereusing6and7)toinput1andinput2ontheL293D.ConnectyourArduinosGNDtobothGNDpinsonthesamesideoftheL293D.Finally,connectoutput1andoutput2oftheL293Dtoyourmotorpins.WhatisHbridgeinl293d?H-BridgeCircuit.AHbridgeisanelectroniccircuitthatallowsavoltagetobeappliedacrossaloadinanydirection.H-bridgecircuitsarefrequentlyusedinroboticsandmanyotherapplicationstoallowDCmotorstorunforwardbackward.WhatisthefunctionofHbridge?AnH-bridgeisanelectroniccircuitthatswitchesthepolarityofavoltageappliedtoaload.ThesecircuitsareoftenusedinroboticsandotherapplicationstoallowDCmotorstorunforwardsorbackwards.Whatisl293dmotordrivershield?L293DshieldisadriverboardbasedonL293IC,whichcandrive4DCmotorsand2stepperorServomotorsatthesametime.Eachchannelofthismodulehasthemaximumcurrentof1.2Aanddoesntworkifthevoltageismorethan25vorlessthan4.5v.HowdoIusethel293dmotordrivermodule?Connect5VtoEnable1,Vss,andVsontheL293D.Connectdigitaloutputpins(wereusing6and7)toinput1andinput2ontheL293D.ConnectyourArduinosGNDtobothGNDpinsonthesamesideoftheL293D.Whatisthedifferencebetweenl293dandl298n?L293isquadruplehalf-HdriverwhileL298isdualfull-Hdriver,i.e,inL293allfourinput-outputlinesareindependentwhileinL298,ahalfHdrivercannotbeusedindependently,onlyfullHdriverhastobeused....Hence,heatsinkisprovidedinL298.DescriptionUC3842isacurrentcontrolpulsewidthmodulationchipwithexcellentperformance.UC3842modulatorsingle-endedoutputcandirectlydriveabipolarpowertubeorfield-effecttube.CatalogUC3842BDocumentsandMediaUC3842BAdvantagesUC3842BFeaturesUC3842BSimplifiedBlockDiagramUC3842BPinoutUC3842BPackageInformationUC3842BBlockDiagramUC3953BTimingDiagramUC3953BPackagesUC3842BCircuitProductManufacturerOrdering&QuantityUC3842BDocumentsandMediaPCNAssembly/OriginPDIP-8AssemblyRevised03/Sep/2013DatasheetsUC384(2,3)B,UC284(2,3)BHTMLDatasheetUC384(2,3)B,UC284(2,3)BEnvironmentalInformationMaterialDeclarationUC3842BNGEDA/CADModelsDownloadfromUltraLibrarianOnlineCatalogMulti-TopologyUC3842BAdvantagesTheUC3842B,UC3843Bseriesarehighperformancefixedfrequencycurrentmodecontrollers.TheyarespecificallydesignedforOffLineandDCDCconverterapplicationsofferingthedesigneracosteffectivesolutionwithminimalexternalcomponents.Theseintegratedcircuitsfeatureatrimmedoscillatorforprecisedutycyclecontrol,atemperaturecompensatedreference,highgainerroramplifier,currentsensingcomparator,andahighcurrenttotempoleoutputideallysuitedfordrivingapowerMOSFET.Alsoincludedareprotectivefeaturesconsistingofinputandreferenceundervoltagelockoutseachwithhysteresis,cyclebycyclecurrentlimiting,programmableoutputdeadtime,andalatchforsinglepulsemetering.Thesedevicesareavailableinan8pindualinlineandsurfacemount(SOIC8)plasticpackageaswellasthe14pinplasticsurfacemount(SOIC14).TheSOIC14packagehasseparatepowerandgroundpinsforthetotempoleoutputstage.TheUCX842BhasUVLOthresholdsof16V(on)and10V(off),ideallysuitedforofflineconverters.TheUCX843BistailoredforlowervoltageapplicationshavingUVLOthresholdsof8.5V(on)and7.6V(off).UC3842BFeaturesTrimmedOscillatorforPreciseFrequencyControlOscillatorFrequencyGuaranteedat250kHzCurrentModeOperationto500kHzAutomaticFeedForwardCompensationLatchingPWMforCycleByCycleCurrentLimitingInternallyTrimmedReferencewithUndervoltageLockoutHighCurrentTotemPoleOutputUndervoltageLockoutwithHysteresisLowStartupandOperatingCurrentThisisaPbFreeandHalideFreeDeviceUC3842BSimplifiedBlockDiagramUC3842BPinout8Pin14PinFunctionDescription11CompensationThispinistheErrorAmplifieroutputandismadeavailableforloopcompensation.23VoltageFeedbackThisistheinvertinginputoftheErrorAmplifier.Itisnormallyconnectedtotheswitchingpowersupplyoutputthrougharesistordivider.35CurrentSenseAvoltageproportionaltoinductorcurrentisconnectedtothisinput.ThePWMusesthisinformationtoterminatetheoutputswitchconduction.47RT/CTTheOscillatorfrequencyandmaximumOutputdutycycleareprogrammedbyconnectingresistorRTtoVrefandcapacitorCTtoground.Operationto500kHzispossible.5GNDThispinisthecombinedcontrolcircuitryandpowerground.610OutputThisoutputdirectlydrivesthegateofapowerMOSFET.Peakcurrentsupto1.0Aaresourcedandsunkbythispin.712VCCThispinisthepositivesupplyofthecontrolIC.814VrefThisisthereferenceoutput.ItprovideschargingcurrentforcapacitorCTthroughresistorRT8PowerGroundThispinisaseparatepowergroundreturnthatisconnectedbacktothepowersource.Itisusedtoreducetheeffectsofswitchingtransientnoiseonthecontrolcircuitry.11VCTheOutputhighstate(VOH)issetbythevoltageappliedtothispin.Withaseparatepowersourceconnection,itcanreducetheeffectsofswitchingtransientnoiseonthecontrolcircuitry.9GNDThispinisthecontrolcircuitrygroundreturnandisconnectedbacktothepowersourceground.2,4,6,13NCNoconnection.Thesepinsarenotinternallyconnected.UC3842BPackageInformationDocumentTitleDocumentID/SizeRevisionRevisionDate8LEADPDIP626-05(51kB)POct,2019SOIC-14NB751A-03(49kB)LOct,2019SOIC-8NarrowBody751-07(53kB)AKOct,2019UC3842BBlockDiagramUC3953BTimingDiagramUC3953BPackagesUC3842BCircuitOscillatorConfigurationExternalClockSynchronizationExternalDutyCycleClampandMulti-UnitSynchronizationAdjustableReductionofClampLevelSoft-StartCircuitAdjustableBufferedReductionofClampLevelwithSoft-StartCurrentSensingPowerMOSFETCurrentWaveformSpikeSuppressionMOSFETParasiticOscillationsBipolarTransistorDriveIsolatedMOSFETDriveLatchedShutdownErrorAmplifierCompensationSlopCompensation27WOff-LineFlybackRegulatorProductManufacturerONSemiconductor(Nasdaq:ON)isdrivingenergyefficientinnovations,empoweringcustomerstoreduceglobalenergyuse.Thecompanyoffersacomprehensiveportfolioofenergyefficientpowerandsignalmanagement,logic,discreteandcustomsolutionstohelpdesignengineerssolvetheiruniquedesignchallengesinautomotive,communications,computing,consumer,industrial,LEDlighting,medical,military/aerospaceandpowersupplyapplications.ONSemiconductoroperatesaresponsive,reliable,world-classsupplychainandqualityprogram,andanetworkofmanufacturingfacilities,salesofficesanddesigncentersinkeymarketsthroughoutNorthAmerica,Europe,andtheAsiaPacificregions.

UC3526

IDescriptionThisblogintroducesasimplemethodtodrivesteppermotorsusingL297andL298chips.Thesteppingmotordrivesystemdesignedbythismethodhasthefollowingcharacteristics:simplehardwarestructure,easysoftwareprogrammingandlowprice.IDescriptionIIIntroductionIIIL297andL298Hardwarecircuit3.1L297Overview3.2L298Overview3.3L297andL298CircuitIVSoftwaredesignFAQOrdering&QuantityIIIntroductionSteppermotorisoneofthecommonlyusedembeddedmotioncontrolequipmentinindustrialcontrol.Thisisbecausesteppermotorscanmoveatdiscretesteps,provideaccurateangularpositioninformation,andareeasiertocontrol.WiththeuseofL297andL298chipstogether,arelativelylowpricecanbeusedtoformasteppermotordrivecircuitwithgoodperformance.StandardsteppermotordriverusingL297andL298ICIIIL297andL298Hardwarecircuit3.1L297OverviewL297isasteppermotorcontroller.Itissuitableforthecontrolofbipolartwo-phasesteppermotorsorunipolarfour-phasesteppermotors.Therearethreedrivemodes:half-step,full-step,andwave.Theon-chipPWMchoppercircuitallowsswitchingcontrolofthewindingcurrent.Anotablefeatureofl297isthatonlyclock,direction,andmodeinputsignalsarerequired.Thephaserequiredbythesteppingmotorisgeneratedinsidethecircuit,whichgreatlyreducestheburdenontheCPU.L297hasthefollowingcharacteristics:Normal/wavedriveHalf/fullstepmodesClockwise/anticlockwisedirectionSwitchmodeloadcurrentregulationProgrammableloadcurrentFewexternalcomponentsResetinputhomeoutputEnableinput3.2L298OverviewL298isahigh-voltageandhigh-currentdualfull-bridgedriverwithtwoH-bridges.ItacceptsstandardTTLlogiclevelsignalsandcandrivesteppermotorswithavoltageof46Vand2.5Aperphaseorbelow.Eachbridgehasanenableinput,whichallowsorprohibitsthedevicetoworkwithoutbeingaffectedbytheinputsignal.Theemittersofthetwolow-endtransistorsofeachbridgeareconnectedtogetherandledoutforexternaldetectionresistance.Itsetsanadditionalpowerinputterminaltomakethelogicpartworkatlowvoltage.Figure1.L298internallogicdiagram(halfofthediagram)L298hasthefollowingcharacteristics:Operatingsupplyvoltageupto46vTotalDCcurrentupto4A25wratedpower2enablecontrolterminalstoenableordevicewithoutinputtingsignals.Abletodriveatwo-phasesteppermotor,four-phasesteppermotorortwoDCmotorsBuilt-instabilivolttube78M05canbeusedtoobtain5vfrompowersupply.(Mustbeusedwithanexternal5vlogicsupplywhendrivevoltageisgreaterthan12vtoprotectthechip)LowsaturationvoltageOvertemperatureprotectionLogical0inputvoltageupto1.5V(highnoiseimmunity)Operatingtemperature:-23Cto130CStorageTemperature:-40Cto150C3.3L297andL298CircuitL297andL298canbeusedtomakeatwo-phasebipolarsteppermotordrivecircuit.Itisdrivenbyaconstantcurrentmode,andthepeakcurrentofeachphasecanreach2A.L297isasteppermotorcontrollerthatisusedtogeneratetwo-phasebipolar.Drivesignal(A,B,C,D)andmotorcurrentsettings.L298isusedtodrivethepoweroutputofthesteppermotor.Itisdrivenbyadoublefullbridgemode.Duetothebipolardrive,themotorcoilisfullyutilizedtoenableintothemotorcanachievethebestdrive.WhentwopiecesofL297areusedtodrivethetwowindingsofasteppingmotorthroughL298,andtheVrefcorrespondingtoeachwindingischangedthroughtwoD/Aconverters,asteppingmotorsubdivisiondrivingcircuitisformed.TheprincipleofL297+L298drivewiringisshowninFigure2.PortsP0~P4arerespectivelyconnectedtothecorrespondingcontrolterminalsofL297.Then,throughthereasonablearrangementofthesoftware,thepurposeofcontrollingthemotortorotateintheexpecteddirectionisachieved.Figure2.ElectricalschematicdiagramInaddition,theterminal1ofL297isthesynchronousterminal,whichcanbeconnectedtotheterminal1ofanothergroupofL297andL298drivecircuits.Inthisway,thetwosetsofdriverscanbesynchronizedtoachievetheeffectofdrivingmultiplemotorsatthesametime.IVSoftwaredesignUseClanguagetowriteprogramcode:P0_0=1;//CWP0_1~1;//HALFP0_3=1;//ENABLEP0_2=1;//RESETP0_7=1;//CLOCKTMODone0X01;//TlTH0=(a4000/256);TL0=one(4000%256);TR0=1;for(;;){TH0=one(4000/256);TL0=one(4000%256);do{}while(!TF0);P0_7=!P0_7;//CLOCKTF0=0;}Thespeedofthemotorspeedcanbecontrolledbythetimer.Figure3.WaveformdiagramgeneratedbyL297AccordingtothewaveformgeneratedbyL297,infact,whentheCPUportresourcesarenottight,theCPUcanbeusedtosimulateoutput.Theabovehardwarecircuitsandsoftwareprogramshavebeentestedandarecompletelypractical.FAQWhatisl298n?ThisL298NMotorDriverModuleisahighpowermotordrivermodulefordrivingDCandStepperMotors.ThismoduleconsistsofanL298motordriverICanda78M055Vregulator.L298NModulecancontrolupto4DCmotors,or2DCmotorswithdirectionalandspeedcontrol.WhatisL297?TheL297integratesallthecontrolcircuitryrequiredtocontrolbipolarandunipolarsteppermotors.UsedwithadualbridgedriversuchastheL298Nformsacompletemicroprocessor-to-bipolarsteppermotorinterface.Howdoesl298ncontrolDCmotorspeed?1.IfyousendaHIGHsignaltotheenable1pin,motorAisreadytobecontrolledandatthemaximumspeed;2.IfyousendaLOWsignaltotheenable1pin,motorAturnsoff;3.IfyousendaPWMsignal,youcancontrolthespeedofthemotor.Themotorspeedisproportionaltothedutycycle.Whatisl298nmotordrivermodule?ThisL298NMotorDriverModuleisahighpowermotordrivermodulefordrivingDCandStepperMotors.ThismoduleconsistsofanL298motordriverICanda78M055Vregulator.L298NModulecancontrolupto4DCmotors,or2DCmotorswithdirectionalandspeedcontrol.Howdoesl298nmotordriverwork?TheL298NisadualH-BridgemotordriverwhichallowsspeedanddirectioncontroloftwoDCmotorsatthesametime.ThemodulecandriveDCmotorsthathavevoltagesbetween5and35V,withapeakcurrentupto2A.Howdoiuseal298motordriverwithArduino?Startbyconnectingpowersupplytothemotors.InourexperimentweareusingDCGearboxMotors(alsoknownasTTmotors)thatareusuallyfoundintwo-wheel-driverobots.Theyareratedfor3to12V.So,wewillconnectexternal12VpowersupplytotheVCCterminal.WhatisthefunctionofHbridge?AnH-bridgeisanelectroniccircuitthatswitchesthepolarityofavoltageappliedtoaload.ThesecircuitsareoftenusedinroboticsandotherapplicationstoallowDCmotorstorunforwardsorbackwards.Whatistheuseofl298n?TheL298NisadualH-BridgemotordriverwhichallowsspeedanddirectioncontroloftwoDCmotorsatthesametime.ThemodulecandriveDCmotorsthathavevoltagesbetween5and35V,withapeakcurrentupto2A.I.IntroductiontoGalvanometerThegalvanometerisanimportanttestinginstrument.Itisahigh-sensitivitymechanicalindicatingmeterfordetectingweakelectricity.Itisusedasazero-pointinginstrumentinbridgesandpotentiometers.Itcanalsobeusedtomeasureweakcurrents,voltagesandcharges..Accordingtotheinputmode,itcanbedividedintovoltagetypeandcurrenttype.Generally,voltagetypeismorecommonlyused.Fromthepaneldisplaymodeofthegalvanometer,itcanbedividedintothreetypes:pointertype,digitaltype,andmixedtype.Figure1ThegalvanometerThepointergalvanometercanconvenientlyobservethecontinuouslychangingcurrent,andintuitivelyjudgethedirectionofthecurrentfromthedeflectiondirection,soithasitsuniqueadvantagesinthebridgeexperiment.Thepointergalvanometerscurrentlyusedinphysicalexperimentshavethefollowingshortcomings:(1)Use9Vlaminatedbatterywithsmallcapacity,shortbatterylifeandhighcost;(2)ItsinternalamplifyingcircuitadoptsOP07orICL7650design,withoutpowermanagementcapability,itiseasytocausethebatterytobeconsumedunnecessarily;(3)Duetotheuseofmanydiscretecomponents,theamplifierispronetodriftandunstable.Thispaperusesagalvanometerdesignedbasedonthethree-op-amphighcommon-moderejectionratioandhighstabilityinstrumentationamplifierAD620andMicrochips6-pinMCUPIC10F206tosolvetheaboveproblems.CatalogI.IntroductiontoGalvanometerII.HardwareSystemDesign2.1HardwareSystemBlockDiagram2.2InstrumentationAmplifierAD6202.3MicrocontrollerPIC10F2062.4AmplifyingCircuitofGalvanometer2.5PowerMonitoringandPowerManagementCircuitofGalvanometerIII.SoftwareSystemIV.ConclusionFAQOrdering&QuantityII.HardwareSystemDesign2.1HardwareSystemBlockDiagramTheblockdiagramofthehardwaresystemisshowninFigure2.TheDCvoltagesignalfirstpassesthroughananti-radiofrequencyinterferencelow-passfiltercircuit,weakenstheinterferencesignal,andthensendsittotheinstrumentationamplifierAD620fordifferentialamplification,andthendrivesthepointermetertodisplay.The6-pinmicrocontrollerPIC10F206isresponsibleforthepowermonitoringandpowermanagementofthegalvanometer.Thewholegalvanometeronlyuses3VDCpowersupplyconnectedinserieswithtwoAAbatteries.Figure2Thehardwaresystemblockdiagramofthegalvanomete2.2InstrumentationAmplifierAD620AD620isalow-costandhigh-precisioninstrumentationamplifierlaunchedbytheAmericanADIcompany.Ithasthecharacteristicsofhighaccuracy,lowoffsetvoltage(maximum50uV)andlowoffsetdrift(maximum0.6uV℃/),anditsmaximumoperatingcurrentisonly1.3mA,onlyanexternalresistorisneededtosetthegain,andthegainrangeis1to10000.Inaddition,AD620adopts8-pinSOICandDIPpackage,thesizeissmallerthanthediscretecircuitdesign,andthepowerconsumptionislower,soitissuitableforbattery-poweredinstrumentapplications.Figure3AD620BecauseitsinputstageusesSuperetaprocessing,itcanachievealowinputbiascurrentofupto1.0nA.AD620hasalowinputvoltagenoiseof9nV/Hzat1kHz,apeak-to-peaknoiseof0.28Vinthefrequencybandfrom0.1Hzto10Hz,andaninputcurrentnoiseof0.1pA/Hz,soitcanbeusedasapreamplifierwell.Atthesametime,the0.01%settlingtimeofAD620is15s,whichisverysuitableformultiplexingapplications;andthecostisverylow,enoughtorealizethedesignofaninstrumentationamplifierperchannel.2.3MicrocontrollerPIC10F206PIC10F206isalow-cost,6-pin8-bitflashmicrocontrollerintroducedbytheUSMicrochipcompanythatusesRISCarchitecture.PIC10F206has512wordsofFLASH,24bytesofSRAM,watchdogtimer(WDT),power-onresetcircuit(POR)anddeviceresettimer(DRT)and4MHzinternaloscillator,thuseliminatingtheneedforexternalresetcircuitandthecrystaloscillator,reducessystemcostandpowerconsumption,andenhancessystemreliability.Italsohasawideoperatingvoltagerange(20Vto5.5V).Theabovecharacteristicsmakeitsuitableforapplicationsinprice-sensitiveandbattery-poweredareas.Figure4PIC10F2062.4AmplifyingCircuitofGalvanometerTheamplifyingcircuitofgalvanometertakestheinstrumentamplifierAD620asthecoreelement,asshowninFigure5.ThedifferentialsignaloutputbytheDCbridgeisinputfromthesocketJ1,passesthroughtheanti-radiofrequencyinterferencelow-passfiltercircuit[2]formedbyR1,R2,C1,C2,C3,andreachestheinstrumentationamplifierAD620afterweakeningtheinterferencesignal.D1,D2andR1,R2togetherformtheinputprotectioncircuitofthegalvanometer,whichcanwithstandinputvoltagesoftensofvolts.R3,R4providealoopfortheinputbiascurrentofAD620[1]toensurethatitcanworkstablyandreliably.TheresistanceR0andpotentiometerRP1betweenpin1andpin8ofAD620aregainadjustmentresistors,denotedasRG.R0isconnectedinserieswithRP1tolimittheupperlimitofthemagnificationto495times.ThepotentiometerRP2andR5,R6formthezeroadjustmentcircuitofthegalvanometertogether,realizezeroadjustmentbychangingthevoltageoftheREFpinofAD620.R7andC7formtheoutputlow-passfilterofAD620.R7,D3,D4constitutetheprotectioncircuitofthepointermeterhead.Figure5TheamplifyingcircuitofgalvanometerThemaximumsensitivityofagalvanometerisusually10uV/degreeto15uV/degree,whichcanwellmeettherequirementsoftheexperiment.TheinternalresistanceRgofthegalvanometermeterheadis4.7k,thegainadjustmentresistanceRG=R0+RP1,takeR0=100,R7=1k,whenRP1is0,theamplificationfactorofAD620isTakingintoaccountthepartialpressureofR7andtheinternalresistanceRgofthemeter,themagnificationofthegalvanometerisThecurrentsensitivityofthemeterheadis1Aminute/degree,sothevoltagesensitivityofthemeterheadis4700Vminute/degree.ThesensitivityofthegalvanometerisS=4700/G=115V/divisionMeettherequirementsofphysicalexperiments.2.5PowerMonitoringandPowerManagementCircuitofGalvanometerFigure6isthepowermonitoringandpowermanagementcircuitofthegalvanometer.TheGP2pinofthemicrocontrollerPIC10F206isconnectedwiththeP-channelMOSFETtubeQ1,thepurposeistocontrolwhethertosupplypowertotheamplifyingcircuitofthegalvanometer.WhenGP2outputislowlevel,Q1isturnedon,andthesystemsuppliespowertotheamplifiercircuit.TheroleofICL7660inpowerconversionhereistoconvert+VSto-VS.R8,R9andtheanalogcomparatorinsidePIC10F206togetherformthepowersupplyvoltagemonitoringcircuit.ThenegativeinputterminalCINoftheanalogcomparatorisconnectedtotheinternalreferencevoltageofthesingle-chipmicrocomputer(thenominalvalueofthevoltageis06V),andthepositiveinputterminalCIN+isconnectedwiththepartialpressureofR8andR9.BecausethelowestoperatingvoltageofAD620is23V,fromaconservativepointofview,thelowerlimitoftheoperatingvoltageissetto2.5V.Whenthepositivepowersupplyvoltageislessthan2.5V,thevoltageofCIN+islessthan0.6V,andthecomparatoroutputisreversed.Afterthemirocontrollerdetectsthisevent,theGP2outputshighlevel,turnsoffthepowersupplyoftheamplifiercircuit,andthenexecutestheSLEEPinstructiontomakethemicrocontrollerentersleepstatus.Figure6PowermonitoringandpowermanagementcircuitofgalvanometerInordertosavepowerconsumption,whentheworkingvoltageisnormal,thegalvanometershouldenterthesleepstate(iesoftshutdown)afterworkingforaperiodoftime,anditcanbeawakenedatanytimewhenitneedstowork.ButtonS1issetforthisfunction.Theworkingtimeofthegalvanometerispresetto15minutes.Whentheworkingtimeisup,theGP2ofthesingle-chipmicrocomputeroutputsahighlevel,shutsoffthepowersupplyoftheamplifyingcircuit,andthenexecutestheSLEEPinstructiontomakethemicrocontrollerenterssleepstate.Inthesleepstate,ifS1ispressed,thepinlevelofGP3willchange.Thiseventwillresetthemicrocontroller(note:PIC10F206hasnoconventionalinterruptfunction)andwakeupthemicrocontroller.Inthesleepstate,thecurrentconsumptionofthegalvanometerislessthan0.1A,whichisverypower-saving,sothereisnoneedtoworryaboutforgettingtoturnoffthepowersupplyofthegalvanometerandconsumingthebattery.III.SoftwareSystemWhenthegalvanometerispoweredon,themicrocontrollerfirstperformssysteminitialization,thensuppliespowertoICL7660andAD620,andthenturnsontheanalogcomparatortocheckwhetherthesupplyvoltageisappropriate.Ifthevoltageisappropriate,continuetosupplypowertotheamplifiercircuit,andthenexecutea15-minutecountdown.IfS1ispressedduringthisperiod,thetimingtimeisresetto15minutes.Whenthe15-minutecountdownisup,thesingle-chipmicrocomputerturnsoffthepowersupplyoftheamplifiercircuit,andthenentersthesleepstate(ie,softshutdown).TheflowchartoftheprocedureisshownasinFig.7.Figure7FlowchartoftheprocedureIV.ConclusionThisarticlediscussesthegalvanometerbasedoninstrumentationamplifierAD620andmicrocontrollerPIC10F206,whichhasstableperformanceandlowpowerconsumption.Thecurrentisabout4mAduringnormaloperation,andthecurrentconsumedinsleepmodeislessthan0.1uA,whichisverysuitableforbatterypowersupply.TheuseoftwoAAbatteriesforpowersupplysavesbatterycost.Thesoftshutdownfunctioncaneffectivelypreventbatteryconsumptioncausedbyforgettingtoturnoffthepower.FAQWhatisAD620?AD620isalow-cost,high-precisioninstrumentationamplifier.Itonlyrequiresanexternalresistortosetthegain.Thegainrangeis1to10,000.CanIchangeAD620toAD623whenmakingMCUproducts?BothAD620andAD623aresingleinstrumentationamplifiers,andthepinarrangementisexactlythesame.Themaindifferenceis:AD620mustusepositiveandnegativepowersupplies,AD623canbeapositiveandnegativepowersupplyorasinglepowersupply.IftheoriginalboardisAD620,youcanreplaceitwith623;iftheoriginalboardisAD623,youmaynotbeabletoreplaceitwith620(itdependsonwhetherthepowersupplyoftheoriginalboardcircuitisdualpowersupplyorsinglepowersupply).AfterreplacingAD620andAD623insingle-chipproducts,theprogramcanworknormallywithoutmodification.WhatisthedifferencebetweenAD620BRandAD620AN?Theirpackagesaredifferent.WhatistheoutputresistanceofAD620?Howtoadjustit?AD620isakindoflowpowerconsumptioninstrumentamplifier,itsoutputresistanceisabout10K,thisistheinherentcharacteristicofthischip,generallyitisdifficulttoadjust.Ifyouhaverequirementsforoutputresistance,youcangenerallyuseanexternalcircuittosolveit.IsAD620apositivephaseamplificationorareversephaseamplification?AD620isaninstrumentamplifier,theoutputvoltageis[(Vin+)-(Vin-)]*gain.Ifthedesiredsignalis(Vin+)-(Vin-),thegainispositive,whichisequivalenttopositiveamplification.Conversely,ifthedesiredsignalis(Vin-)-(Vin+),thegainisequivalenttonegative,whichisequivalenttoreverseamplification.Whatisaninstrumentationamplifier?Instrumentationamplifier,animprovementofthedifferentialamplifier,hasaninputbuffer,doesnotrequireinputimpedancematching,sothattheamplifierissuitableformeasurementandelectronicinstrumentsIDescriptionTheperformanceandstructureofthesteppermotordriverchipL297/L298areanalyzed.Atthesametime,combinedwiththeAT89C52single-chipmicrocomputer,asimplemethodofdrivingasteppermotorisintroduced.Thisbloggivesthecontrolschematicdiagram.Theactualmeasurementshowsthatthesteppingmotordrivesystemdesignedbythismethodhasthecharacteristicsofsimplehardwarestructure,easysoftwareprogrammingandlowprice.CatalogIDescriptionIIIntroductionIIIWorkingprincipleVIHardwareVSoftwareCompositionVIConclusionOrdering&QuantityIIIntroductionWhatisasteppingmotor?Asteppingmotorisaprecisionactuatorthatconvertselectricalpulsesignalsintoangulardisplacementorlineardisplacement.Thesteppingmotorhasthecharacteristicsofconvenientcontrolandsmallsize.Therefore,itiswidelyusedinnumericalcontrolsystems,automaticproductionlines,automaticinstruments,plotters,andcomputerperipherals.L297andL298caneasilyformasteppingmotordriver,andcombinedwithAT89C52single-chipmicrocomputerforcontrol.Thatis,itispossibletoformasteppermotordrivecircuitwithgoodperformanceatarelativelycheapprice.IIIWorkingprincipleSinceasteppermotorisanactuatorthatconvertselectricalpulsesignalsintolinearorangulardisplacement,itcannotbedirectlyconnectedtoACandDCpowersupplies.Instead,aspecialdevice,asteppingmotor,mustbeusedtocontrolthedriver.AtypicalsteppingmotorcontrolsystemisshowninFigure1.Thecontrollercansendoutpulsesignalswhosepulsefrequencycanbecontinuouslychangedfromafewhertztotensofkilohertz.Itprovidesapulsetrainfortheringdistributor.Themainfunctionoftheringdistributoristodistributethepulsesequencefromthecontrollinkaccordingtoacertainrule.Thenitisamplifiedbythepoweramplifierandaddedtotheinputterminalsofthesteppingmotordrivepowersupplytodrivetherotationofthesteppingmotor.Therearetwomaincategoriesofringdistributors:Oneistousecomputersoftwaredesignmethodstoachievethefunctionsrequiredbytheringdivider,usuallycalledasoftringdivider.Theotherisaringdistributorcomposedofhardware.Usuallycalledahardringdistributor.Thepoweramplifiermainlyamplifiesthesmalleroutputsignaloftheringdistributortoachievethepurposeofdrivingthesteppermotor.Figure1.TypicalsteppermotorcontrolblockdiagramVIHardwarehesteppermotorcontrolledintheblogisafour-phaseunipolar35BY48HJ120decelerationsteppermotor.TheblockdiagramofthesteppermotorcontroldriverdesignedinthisblogisshowninFigure2.ItconsistsofAT89C52single-chipmicrocomputer,optocoupler,integratedchipsL297andL298.Figure2.BlockdiagramofsteppermotorcontroldriverThesteppermotorintroducedintheblogisafour-phaseunipolar35BY48HJ120decelerationsteppermotor.TheblockdiagramofthesteppermotorcontroldriverdesignedinthisarticleisshowninFigure2.ItiscomposedofAT89C52single-chipmicrocomputer,photoelectriccoupler,integratedchipsL297andL298.AT89C52isalow-voltage,high-performance8-bitCMOSmicrocontrollerfromATMELintheUnitedStates.Thechiphasabuilt-in8Kbytesofre-erasableFlashmemory,256bytesofRAM,three16-bittimers,andaprogrammableserialUARTchannel.Therefore,itissufficienttocompletethesimplecontrolofthesteppermotor.L297isasteppingmotorcontroller(includingringdistributor).L298isadoubleHbridgedriver.Theinterfaceofthemicroprocessortothedouble-bridgesteppingmotorcomposedofthemisshowninFigure3.Theadvantageofthiscombinationisthatitrequiresfewcomponents.Asaresult,theassemblycostislow,thereliabilityishigh,andthespaceissmall.Andthroughsoftwaredevelopment,theburdenofmicrocomputerscanbesimplifiedandreduced.Inaddition,L297andL298areindependentchips,sotheapplicationisveryflexible.TheL297chipisahardwareloopintegratedchipthatcangeneratefour-phasedrivesignalsforcomputer-controlledtwo-phasebipolarorfour-phaseunipolarsteppermotors.TheheartoftheL297isasetofdecodersthatcangeneratevariousrequiredphasesequences.Thispartiscontrolledbytwoinputmodes,directioncontrol(CW/CCW)andHALF/FULL,andsteppingclockCLOCK.Itadvancesthedecoderfromonesteptoanother.Thedecoderhasfouroutputpointsconnectedtotheoutputlogicsectiontoprovidethephasesequencerequiredbythesuppressionandchoppingfunctions.Therefore,L297cangeneratethree-phasesequencesignals,correspondingtothreedifferentworkingmodes:thehalf-stepmode(HALFSTEP).Basicstep(FULLSTEP,fullstep)one-phaseexcitationmethod.Basicsteptwo-phaseexcitationmethod.Insidethepulse,thedistributorisa3bitreversiblecounter,plussomecombinationallogictogenerate8stepsofGraycodetimingsignalpercycle.Thisisthetimingsignalofthehalf-stepworkingmode.Atthistime,theHALF/FULLsignalishigh.IfHALF/FULLissettoalowlevel,thebasicstepworkingmodeisobtained,thatis,thedoublefour-beatfull-stepworkingmode.Figure3.L297PictureAnotherimportantcomponentofL297isthetwoPWMchopperstocontrolthephasewindingcurrentstoachieveconstantcurrentchoppingcontroltoobtaingoodtorque-frequencycharacteristics.Eachchopperconsistsofacomparator,anRSflip-flopandanexternalsamplingresistor.Acommonoscillatorisalsoprovidedtoprovidetriggerpulsesignalstothetwochoppers.InFigure5,thefrequencyfisdeterminedbytheexternal16-pinRCnetwork.WhenR10k,f=1/0.69RC.Whentheclockoscillatorpulsesetsthetriggerto1,themotorwindingphasecurrentrises.WhenthevoltageonRsofthesamplingresistorrisestothereferencevoltageUref,thecomparatorflipstoresettheflip-flop,thepowertransistoristurnedoff,andthecurrentdrops,waitingforthearrivalofthenextoscillationpulse.Inthisway,theoutputofthetriggerisaconstantfrequencyPWMsignal,whichmodulatestheoutputsignalofL297,andthepeakvalueofthewindingphasecurrentisdeterminedbyUref.TheinputoftheCONTROLterminalofL297determinesthatthechopperactsonthephaselinesA,B,C,DorthesuppressionlinesINH1andINH2.WhenCONTROLishigh,ithascontroleffectonA,B,C,D;Whenitislowlevel,itcontrolsINH1andINH2,sothatthesteeringandtorqueofthemotorcanbecontrolled.TheL298chipisahigh-voltage,high-currentdualfull-bridgedriver.L298isdesignedtoacceptstandardTTLlogiclevelsignalsanddriveinductiveloads.Forexample,relays,cylindricalcoils,DCmotorsandsteppingmotors.Ithastwosuppressinputstomakethedeviceimmunetotheinputsignal.Theemittersofthetriodesofeachbridgeareconnectedtogether,andthecorrespondingexternalterminalscanbeusedtoconnectperipheralsensingresistors.Anotherinputpowersupplycanbeinstalledtoenablethelogictoworkunderlowvoltage.TheL298chipisanintegratedchipinamulti-wattin-linepackagewith15leads.Figure4.L298PictureInFigure5,AT89C52isconnectedtothemicrocomputerthroughtheserialportafterMAX232levelconversion,andacceptsinstructionsfromthehostcomputer.Thensendclocksignal,positiveandnegativesignal,resetsignalandenablecontrolsignaltoL297.Inthecircuit,resistorsR13andR15areusedtoadjustthereferencevoltageofthechoppercircuit.Thisvoltagewillbecomparedwiththemagnitudeofthepotentialfedbackthroughthepins13,14todeterminewhethertoperformchoppingcontrol.Inordertoachievethepurposeofcontrollingthepeakvalueofthemotorwindingcurrentandprotectingthesteppermotor.BecauseL297hasachoppingconstantcurrentcircuitinside,thepeakvalueofthewindingphasecurrentisdeterminedbyUref.WhentwopiecesofL297areusedtodrivethetwowindingsofthesteppingmotorthroughL298,andtheUrefofeachphasewindingischangedthroughtwoD/Aconverters,thesteppingmotorsubdivisiondrivingcircuitisformed.Inaddition,inordertoeffectivelysuppresselectromagneticinterferenceandimprovethereliabilityofthesystem,anisolationcircuitcomposedoftwo16-pinphotoelectriccouplingdevicesTLP521-4isusedinthesingle-chipandsteppingmotordrivecircuit.AsshowninFigure5.Figure5.SchematicdiagramofsteppermotorcontroldriverItsfunctionistocutoffthedirectelectricalconnectionbetweenthemicrocontrollerandthesteppingmotordrivecircuit.Inthisway,theseparateconnectionofthesingle-chipmicrocomputerandthedrivingcircuitsystemgroundisrealized,andtheinterferencesignalgeneratedbythedrivingcircuitworkingunderthehigh-currentinductiveloadandtheinterferencesignalgeneratedbythesuddenchangeofthegridloadisseriallyconnectedtothesingle-chipmicrocomputerthroughtheline,whichaffectsthenormaloperationofthesingle-chipmicrocomputer.VSoftwareCompositionInthiscircuit,setP1.0portasthemotorstartbutton.P1.1,P1.2,P1.3arespeedselectionbuttons,thespeedisfromlowtohigh.P1.4isthemotorstopbutton.Themaximumspeedofthethreespeedsis500pps,1000pps,and2000pps.RXD,TXDhavebeenconnectedtotheserialportbyMAX232levelconversion.Inaddition,thestartandstopfrequencyofasteppermotorislow,generallybetween100-250Hz.Themaximumoperatingfrequencyisrequiredtobehigher,usually1-3kHz.Inordertoensurethatitwillnotlosestepduringthewholeprocessofstarting,runningandstopping,butalsocanreachthetargetpositionaccuratelyassoonaspossible,therunningspeedmusthaveanacceleration-constantspeed-decelerationprocess.Here,thecommonlyuseddiscretemethodisusedtoapproximatetheidealtrapezoidalaccelerationanddecreasecurve,asshowninFigure5.Thatis,thetimerinterruptmodeisusedtocontinuouslychangethesizeofthetimerloadvalue.Inthisexample,fortheconvenienceofcalculation,theloadingvaluerequiredforthespeedofeachdiscretepointisconvertedintotherequiredtimingtimebytheformulaandsolidifiedintheROMofthesystem.Here,TH0=(65536-time)/256,TL0=(65536-time)%256isusedtocalculatetheloadingvalue,andtimerepresentsthetimingtimerequiredforeachstep.Thesystemusesthelook-uptablemethodtofindoutthetimerequiredduringoperation,therebygreatlyreducingthetimeoccupiedbytheCPUandimprovingthecorrespondingspeedofthesystem.Therefore,theprogramismainlycomposedofcontrolmainprogram,accelerationanddecelerationsubroutine,andthemainprogramblockdiagramisshowninFigure6.Figure6.MainblockdiagramVIConclusionTheinnovationofthisblogistoproposetheapplicationofsingle-chipmicrocomputerandL297,L298integratedcircuitstoformasteppermotorcontroldriver.Ithastheadvantagesoffewercomponents,highreliability,lessspace,andlowassemblycost.

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IDescriptionDoyouknowtheDCregulatedpowersupply?DCregulatedpowersupplyiswidelyusedinindustrialproductionanddailylife,anditsdesignoccupiesaveryimportantpositioninpowersupplytechnology.Therefore,basedontheanalysisoftheproblemsofthetraditionalDCstabilizedpowersupply,themethodandcalculationofeachpartofthe5V,1ADCstabilizedpowersupplybasedonL7805CTaredescribed.Besides,itcanalsoprovidea5VDCpowersupplyforcounters,decoders,anddigitaltubestorealizeadditionandsubtractioncounting.ThesystemcircuitbasedonL7805CTintroducedinthisblogissimple,stable,easytocontrol,cost-effective,andisofhighuse-value.CatalogIDescriptionIIIntroductionIIIDesignrequirementsforDCstabilizedpowersupplyIVHardwareunitcircuitdesign4.1Overallstructureofthepowersupply4.2ComponentselectionVApplicationVIConclusionFAQOrdering&QuantityIIIntroductionWiththecontinuousdevelopmentofelectronictechnology,thedesignrequirementsofelectronicequipmentforpowersupplyaregettinghigherandhigher,fromtraditionalrequirementstohigh-quality,high-efficiency,andhigh-stabilitytomeettheneedsofobjects.ThenormaloperationofelectronicdevicesrequiresDCpower.DCpowersourcesincludesolarbatteries,accumulators,anddrybatteries.Butdoyouknowwhichoneisthemostcost-effective?Ofcourse,themostcost-effectivemethodistoconverttheACpowerprovidedbythegridintotherequiredDCpower.Mostelectronicequipmentusesthismode,andthethree-terminalregulatoristhemostwidelyused.AlthoughpeopleusemanytypesofDCstabilizedpowersupplieswithdifferentfunctions,theprinciplesaresimilar.ThevoltageregulatorchipusedinthesystemintroducedinthisblogisL7805CT.L7805CThastheadvantagesofsmallsize,simpleexternalwiring,stableoperationandstrongapplicability.Itcanmeetpeoplesrequirementsinlife,study,andwork.IIIDesignrequirementsforDCstabilizedpowersupplyThedesignrequirementsoftheDCregulatedsingle-channelpowersupplybasedonL7805CTareasfollows:InputACvoltage220V;OutputDCvoltage+5V;OutputDCcurrent1A;Theoutputrippleofthecircuitislessthan50mV;Theequivalentinternalresistanceislessthan0.15;Ripplecoefficientislessthan0.002%;Voltageadjustmentrate0.001%;Voltagestabilizationcoefficient0.005%.IVHardwareunitcircuitdesign4.1OverallstructureofthepowersupplyThisdesignfocusesontheknowledgeandskillsinvolvedinthemainlinksoftheDCpowersupply,andcompletesthecircuitdesignandproductionof220VACinputand5V,1ADCoutput.TheDCpowersupplyisusuallycomposedoffourlinks:PowerTransformers;Rectifiercircuit;Filtercircuit;Regulatorcircuit.AsshowninFigure1.Figure1.BlockdiagramofDCpowersupply4.1.1PowertransformerThepowertransformerconvertsthehigh-voltageACmainspowerintotheappropriatevoltageACandsendsittothesingle-phasebridgerectifiercircuit.Whenchoosingapowertransformermodel,theparametersweneedtoconsiderarecapacityandoutputvoltage.4.1.2RectifiercircuitTherectifiercircuitusestheunidirectionalconductivityofthediodetocompletetherectification.Commonlyusedrectifiercircuitsareasfollows:single-phasehalf-waverectifiercircuit,single-phasefull-waverectifiercircuitandsingle-phasebridgerectifiercircuit.Throughcomparativeresearch,inordertoovercometheshortcomingsofhalf-waverectification,theL7805CT-basedsystemusesasingle-phasebridgerectifiercircuit.Itconsistsof4diodesVD1~VD4connectedintheformofabridge.Whetheritisapositivehalf-cycleoranegativehalf-cycle,thedirectionofthecurrentflowingtotheloadRListhesame.BothtransformtheACvoltageoutputbythesecondarywindingofthepowertransformerintoapulsatingDCvoltage.Thereversevoltagethateachdevicebearsisthepeakvalueofthepowersupplyvoltage,andsymmetricalcurrentflowsthroughthepositiveandnegativehalfcyclesofthetransformer,theutilizationrateishigherthanthatofthefull-waverectifiercircuit,andthecurrentrippleisreduced.Therefore,thereisnounidirectionalmagnetization.4.1.3FiltercircuitTherectifieddirectcurrentcontainsarelativelylargealternatingcurrentcomponent,andthepulsationcoefficientisrelativelylarge,soitcannotbedirectlyusedasthepowersupplyforelectroniccircuits.FiltercircuitsarecommonlyusedtoremoveorreducetheACcomponentintheoutputvoltage,sothatpureACpowerisusedonthedevice.Thisdesignusestheenergystoragecharacteristicsofcapacitorsandinductorstosetappropriateparameters.Whenthecircuitvoltagerises,theenergystorageelementstoresenergy.Whenthevoltagedrops,theenergystorageelementreleasesenergy,soastoachievethepurposeofreducingpulsation.Thecapacityofthecapacitorisrelatedtothedischargetime.Tomakethefilteringeffectbetter,acapacitorwithalargercapacitycanbeusedasthefiltercapacitor.ThefiltercapacitorisgenerallyselectedasRLC(3~5)T/2.4.1.4VoltagestabilizingcircuitTheDCvoltageobtainedaftertheACpowerisrectifiedandfilteredoftenfluctuateswiththefluctuationofthegridvoltage,temperaturechanges,andloadresistancechanges.Then,thequalityofpowersupplywillbereduced,affectingtheoperationoftheequipment.Therefore,avoltagestabilizingcircuitneedstobeaddedbetweenthefiltercircuitandtheloadlinktoachievethepurposeofstabilizingpowersupply.ThechipL7805CThasthecharacteristicsofgoodvoltageregulationperformance,highreliability,easyinstallationandlowcost.Therefore,thelinearstabilizedpowersupplyreplacesthediscretestabilizedcircuitandiswidelyused.Inordertoreducetheinterferenceandmakethevoltagestabilizingcircuitworknormally,theinputvoltageshouldbeatleast2.5~3Vhigherthantheoutputvoltage.4.2Componentselection4.2.1SelectionofpowertransformerConsideringthediodeforwardvoltagedrop,wireresistance,andpowergridfluctuations,theoutputvoltageUIofthethree-terminalintegratedregulatorshouldmeet:Where:Uomaxisthemaximumoutputofregulatedpowersupply;(UI-UO)ministheminimumvoltagedifferencebetweentheinputandoutputoftheintegratedregulator;UIisthechangeoftheinputvoltagecausedbythefluctuationofthepowergrid(generallytakenas10%ofthesumofUO,(UI-UO)min,andUIP).Fortheintegratedthree-terminalregulator,when(UI-UO)min=2~10V,ithasbettervoltageregulationcharacteristics.WhenU1=10VWhenU2=9VInasingle-phasebridgerectifiercircuit,therelationshipbetweenthetransformersecondarywindingcurrentI2andthecapacitorfilteroutputcurrentIIis:Insummary,chooseatransformerwithacapacityof15VAand9V.4.2.2SelectionofrectifierdiodeBecause,thecurrentflowingthrougheachrectifierdiodeinthebridgecircuitis:Themaximumreversepeakvoltageofeachrectifierdiodeis:Insummary,selectthetransistorIN4001,itsparametersare:ID=1A,URM=50V.4.2.3SelectionoffiltercapacitorAlthoughthecurrentpassingthroughthediodeisapulsatingcurrent,becausethecapacitorChasanenergystorageanddischargefunction,thisreducesthedegreeofvoltagepulsationacrosstheloadRLandincreasestheaveragevalue.TheaveragevalueandsmoothnessoftheDCvoltageontheloadarerelatedtothedischargetimeconstant=RLC.ThelargerthevalueofCorRL,theslowerthedischargeofC.ThelargertheoutputDCvoltagevalue,thebetterthefilteringeffect;otherwise,theworse.Generallytake:TheACpowersupplyinsomeAsiancountriesisa50Hzsinewave,with50identicalwaveformspersecond.Afterfull-waverectification,boththepositiveandnegativehalfwavesbecomepulsatingdirectcurrentinthesamedirection.Atthistime,thereare100identicalwaveformspersecond,thatis,f=100Hz.Sothefiltercapacitorcapacityis:amongthem,TheoutputDCvoltageofthecapacitorfiltercircuitisestimatedas:Insummary,twoelectrolyticcapacitorsof2200Fand50Vcanbeused,andtheyareconnectedinparallel.Inordertofilterouttheinterferenceofhigh-frequencysignalsandimprovethedynamiccharacteristicsofthepowersupply,a105pF,50Vhigh-frequencyceramiccapacitorisconnectedinparallelatbothendsofthefiltercapacitor.4.2.4Howtochooseathree-terminalintegratedvoltageregulatorTheconditionthatthepowerconsumptionofthethree-terminalintegratedvoltageregulatormustmeetisgreaterthan5Wandtheoutputvoltageis5V.ThisdesignchoosesL7805CT,theoutputvoltageis4.8~5.2V,thequiescentcurrentis4.2~8mA,andthemaximumoutputcurrentcanbe1.5A,whichmeetsthedesignrequirements.Consideringthelargeoutputcurrent,aheatsinkneedstobeadded.VApplicationAdoptthedesignbasedonL7805CTtoprovide5VDCpowersupplyforcounter,decoderanddigitaltube.Usethebuttontogenerateasingleclock,realizethecountofmodulo10throughthestandardcountercircuit,andgeneratethecorrespondingcode.Thevalueisoutputtotheintegrateddecodingcircuitthroughthedecodertodisplaythenumbers0-9.UsetheDPsectionoftheintegrateddecodingcircuitasapower-onindication.Thecounterhasaresetbutton,andtheintegrateddecodingcircuitadoptsacommoncathodestructuretorealizeadditionandsubtractioncounting.asshowninfigure2.Figure2.L7805CircuitVIConclusionThe5V,1ADCpowersupplydesignbasedontheL7805CTdescribedinthisblogcanprovide5VDCpowersupplyforcounters,decoders,anddigitaltubestoachieveadditionandsubtractioncounting.ThedesigncircuitoftheL7805CTissimple,withfewcomponents,lowpowerconsumptionandstable.Therefore,itcanbeextendedtootherobjectapplicationsasaDCstabilizedpowersupplytoprovideelectricalenergy.FAQWhatisl7805?AvoltageregulatorICmaintainstheoutputvoltageataconstantvalue.7805IC,amemberof78xxseriesoffixedlinearvoltageregulatorsusedtomaintainsuchfluctuations,isapopularvoltageregulatorintegratedcircuit(IC)....7805ICprovides+5voltsregulatedpowersupplywithprovisionstoaddaheatsink.WhatistheworkingprincipleofIC7805?AvoltageregulatorICmaintainstheoutputvoltageataconstantvalue.7805IC,amemberof78xxseriesoffixedlinearvoltageregulatorsusedtomaintainsuchfluctuations,isapopularvoltageregulatorintegratedcircuit(IC).Thexxin78xxindicatestheoutputvoltageitprovides.HowdoItesta7805withamultimeter?TurnontheDCpowersupplyandadjusttheoutputvoltageofabout8Vorslightlylarger.Oralternativelyyoucanuseabattery9V-12Vasvoltagesource.Lookatthevoltmeterpanelwhenyousetthevoltage.PrepareaDCvoltmeterreadingsonvoltagerange50VtomeasuretheoutputvoltageoftheIC7805.Howdoes7805regulatevoltage?For7805IC,itis+5VDCregulatedpowersupply.ThisregulatorICalsoaddsaprovisionforaheatsink.Theinputvoltagetothisvoltageregulatorcanbeupto35V,andthisICcangiveaconstant5Vforanyvalueofinputlessthanorequalto35Vwhichisthethresholdlimit.I.74HC164Introduction74HC164adoptsDIP-14,SO-14,SSOP-14andTSSOP-14packagepinconfiguration.ItiscomplementarytoMOS8-bitserialinputandparalleloutputunidirectionalshiftregister,thelogicsymbolisshowninthefigure1.Thepowersupplyvoltageis2~6V.Inthefigure1,AandBaretheserialcodeinputterminals;CLRistheclearinputterminal;CLKistheclockpulseinputterminal.Withthearrivaloftherisingedgeoftheclockpulse,thestateofphaseA,phaseBandthesubsequentphaseshiftsfromQAtoQHinturn.CatalogI.74HC164IntroductionII.74HC164LogicSymbolIII.CircuitDesignIV.HowtoCheckandRepairtheCircuitFAQOrdering&QuantityII.74HC164LogicSymbolFigure174HC164LogicSymbolIII.CircuitDesignFigure2isaninstrumentcircuitcomposedofserialinputandparalleloutputdigitalintegratedcircuits.T2-T5,C5andresistancetogetherformaturnsignalflashingoscillationcircuit.WhentheDR(connectedtotheturnswitch)inJ8isdisconnected,thiscircuitwillnotworkandtheturnsignalwillnotflash;whenDRison,theoscillationcircuitstarttowork,theturnsignalstartstoflash.Figure2MetercircuitdiagramDRisathree-positionswitch,onepoleisconnectedtotheleftturnsignal,onepoleisconnectedtotherightturnsignal,onepoleissuspendedintheair,andtheotherendofthepolehitstheground.Theswitch-offcircuitiscomposedofTl,DLRllandR12.Aswitch-typeHallelementisinstalledinthefrontandrearbrakesoftheelectricbicycle.Whentheswitchisswitched,theHallelementoutputsalowpotential,thatis,theBRKterminalintheplugJ2isgrounded,Tlisturnedon,andthereisavoltageofnearly5VonthecollectorofTl.ThisvoltageissenttothecontrollerthroughtheBRKterminalinJ2,andthepowersupplycircuitofthemotoristurnedoff.Themotorstopsworkingandactsasabrake.Onthecontrary,whenthebrakeisnotpinched,theHallelementoutputsahighpotential,Tliscutoff,andthemotorrunsnormally.Because74HC164isan8-bitserialinputandparalleloutputshiftregister,itformsamovementmodeandbatterypowerdisplaycircuitwithlight-emittingdiodes.74HC164soutputpin13,pin11,andD5-D7formthesideofthesportsmodedisplaycircuit,andpins6and10andD8-D12formthebatterypowerdisplaycircuit.Thedisplaysignalfromthecontrollerissenttotheserialinputterminals1and2ofthe74HC164throughtheDATAterminalintheJ2,andthenshiftedbytheinternalcircuit,thedrivingsignalisoutputfromtherelevantoutputterminaltolightupthecorrespondinglight-emittingdiode,soastocompletethecontrolofthedisplaycircuit.IV.HowtoCheckandRepairtheCircuitThiscircuitisrelativelysimpleandeasytorepair.Themainbasisforrepairingistojudgethequalityof74HC164.First,checkwhetherthe+5Vvoltageisnormal,andthencheckwhetherthevoltageatpin③ofthe74HC164sclocksignalinputiscloseto+5V.Ifitislowerthan+5V,andafterdisconnectingR73,theCLKterminalvoltageofJ2isnormal,andthe74HC164isdamaged.IfthevoltageoftheCLKportisabnormal,thefaultisinthecontroller.Next,measurewhetherthevoltageoftheserialinputterminals①and②changesduringthetransitionofthemotionmode.Ifnot,thefaultisinthecontroller;ifthereis,the74HC164isdamaged.Fromtheactualrepairsituation,mostofthe74HC164failuresarecausedbydamagetotheinternalcircuitofthe⑩pin(powersupplyterminal).Inaddition,whenpurchasing74HC164,youcanfirstmeasuretheresistanceofthe⑩pin.Theresistancevalueshouldbeabout4kDinthepositivetestandinfiniteinthereversetest.FAQHowdoesthe74HC164transmitdatainthemicrocontrollercircuit?Onepinofthesingle-chipmicrocomputerislikeafaucet,andthedataissentonebyone,thatis,likethewaterfromthefaucet,drippingdropbydrop.The74H164islikeasmallbowlreceivingwater.Itisjustfullafterreceiving8dropsofwater.Atthistime,itissenttothedigitaltube.Thesingle-chipmicrocomputermustsendan8-bit(ormore)data,ifitissentatthesametime,itisaparalleltransmission,ifitisabitbybit,itisaserialtransmission.Thedataofthesingle-chipmicrocomputerissenttothe74HC164bitbybit,whichisserial,andthe74HC164sendsthedatatothedigitaltubeatonce,whichisparallel.So74HC164playsarolefromserialtransmissiontoparalleltransmission.Whatisthedifferencebetween74HC164Dand74HC164NMCU?TheDin74HC164Drepresentsachippackage.TheNin74HC164Nmeansdualin-lineplasticpackaging.Whatisthedifferencebetween74HC164and74LS164,cantheybeusedtogether?74ls164isaTTLcircuit,thepowersupplyvoltageis5V,thehigh-leveloutputcurrentIohis-0.4MA,andthelow-leveloutputcurrentis8MA.74HC164isaCMOScircuit,thepowersupplyvoltageis2V~6V,theoutputdrivecurrentcanreachplusorminus20MA.Ifthepowersupplyvoltageyouuseis5Vandtheoutputdrivecurrentissuitablefor74ls164,theycanbeusedtogether.Whatdevicescan74hc164bereplacedwith?74HC164isaCMOSdevicewithapowersupplyvoltageof2V-6V.Itcanbedirectlyreplacedby74HCT164,40H164.Ifthepowersupplyvoltageis5Vandtheoutputdrivecurrentissmall,itcanalsobereplacedby74164,74LS164,74F164,74ALS164.Whichof74LS164and74HC164hashigherdrivingcapability?74LS164isaTTLdevicewithahigh-leveldrivingcapabilityofabout0.4mAandalow-leveldrivingcapabilityofabout8mA.74HC164isaCMOSdevice,withhigh-levelandlow-leveldrivecapabilityupto20mA.TheabovedatacomesfromDATASHEET.Butgenerallyspeaking,thehigh-leveloutputcapabilityofmanyCMOSdevicesisweak,smallerthanTTL,andthelow-leveldrivecapabilityisstronger.Can74hc164nbeusedtodrivethedigitaltube?Ofcourse,youcanusethe164chiptodrivethenixietube,whichismostlyusedinsituationswheretheIOportresourcesaretightandthedisplaydatarefreshofthenixietubeisslow.Whendesigningthecircuit,multiple164chipsareusedincascade,nomatterhowmanydigitaltubesaredriven,only2IOportsofthesingle-chipmicrocomputerareoccupied.ItcanbesaidthatitisthemostIOport-savingdrivingmethod,anditisstilldrivenstatically,withoutstrobeandbrightnessLowphenomenon.Thedisadvantageisthatmultiple164sareusedincascadeconnection,whichwillcausethesingle-chipmicrocomputertosendalargeamountofdisplaydata(1bytepernixietube)atonetimewhenrefreshingthedisplaydata.Duringthisprocess,thenixietubewillbeallon,althoughthedataissentTheprocessdurationisveryshort,butitstillaffectsthedisplayeffect.Itisrecommendedtoturnoffthedigitaltubewhenrefreshingthedata.

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I.DescriptionAutomaticgaintechnology(AGC)iswidelyusedinthefieldofindustrialautomationclosed-loopcontrol.Inindustrialcontrol,time-varyinggainamplifiersareoftenneededtomeetproductionneeds,ormadeithasacertainregularitytoensurethestabilityofthecontroloutputamplitude,therebyreducingtheinterferenceoftheinputinterferencenoisesignal.Forthesystemtoadjustquikly,thispaperdesignsanAGCcontrollerbasedonthecombinationofAGCchipAD603andswitchingpowersupplychipMC34063,cleverlyusingMC34063sstablereferencevoltageanddynamicvoltageadjustmentoutputtoaccessAD603gaincontrolterminaltocontroltheamplificationgain,thereforeachievethegoalofconstantsystemoutputamplitude.AD603CatalogI.DescriptionII.WorkingPrincipleoftheSystemIII.AD603IV.MC34063V.SystemHardwareCircuitDiagram5.1InputBufferAttenuationCircuit5.2AD603AutomaticGainAmplifier5.3OutputAmplitudeDetector5.4MC34063FeedbackCircuitVI.SystemOperationResultsVII.ConclusionFAQOrdering&QuantityII.WorkingPrincipleoftheSystemThesystemusesAD603asthecorecontroldevice,supplementedbytheswitchingpowersupplychipMC34063tocollecttheoutputofthecontroller,theoutputvoltageistransferredtothevoltagecontrolterminalofAD603throughMC34063tochangetheamplificationgain.ThesystemworkingprincipleblockdiagramisshownasinFig.1.Figure1SystemBlockdiagramInthisclosed-loopcontrolsystem,theMC34063circuitisusedasitsfeedbacklinktodynamicallycollecttheamplitudeoftheoutputsignalofthesystem,andcontroltheamplificationgainofAD603byadjustingthedutycycleoutputvoltageoftheinternalsignal.Thefeedbacklinkinthefigurecanbereplacedwithamicroprocessor.ThemicroprocessorcollectstheoutputvoltageamplitudethroughA/D,transfersittothemicroprocessorchipforsignalprocessing,andthenfeedsbacktotheinputoftheentiresystemthroughD/Aoutputcontrolvoltage.However,thismethodistoocomplicated,becausetheriseandfallofthedigitalchiptakealongtimetosetup,whichaffectstheresponsespeedoftheentiresystem,andrequiresrelativelyhighsignalprocessingalgorithms.Theswitchingpowersupplychipwidelyusedinpowersupplytechnologyisdynamicallyadjustedtoimproveitsoperatingspeed.Inaddition,itsdevelopmentcostislow,whichisconducivetothepromotionoftheindustrialcontrolfield.III.AD603AD603isachipwithprogrammablegain,lownoise,ithas3workingmodes,correspondingtodifferentgainranges.Inordertomakethecontrolmoreextensive,themaximumbandwidthmodeisselectedas90MHz.Thegainisexpressedindecibels,theamplificationgainiscontrolledbythecontrolvoltagetoalinearrelationshipof25mV/dB,andtheslewrateis275V/s.Thegaincontrolvoltageneedstobeinputduringnormaloperation.Thegainformulais:Intheformula:Gisthegain,dB;G0isthestartingpointofthegain,andthesizeofG0isdeterminedbythepinconnection.Thecircuitdesignedinthispapershort-circuitsVOUTandFDBK,G0=10dBisthewidebandmode(90MHzwideband),thegainrangeGofAD603is-11.09~+31.05dB,andVGisinthelinearrangewhentherangeis-500~500mV.ThegaincontrolvoltageVGiscontrolledbytheMC34063output.AD603inputsignalamplitudeUINP1.4V,theactualindustrialcontrolfieldofteninputplusinterferencesumisgreaterthan1.4V,ifthissignalisdirectlyaddedtothesystem,thedistortionislargeandlong-timeworkwilldamagetheAD603,soyoumustaddaninputbufferandattenuationcircuit.IV.MC34063MC34063isamonolithicbipolarintegratedcircuitusedinthefieldofDC-DCconvertercontrol.Itischeapandwidelyusedinthefieldofswitchingpowersupplies.Itcanuseaminimumofexternalcomponentstoachieveswitchingboostandbuck.Itsoperatingfrequencyis0.1-100kHz.ThetraditionalAGCcontrollerconstitutesaclosed-loopcontrolsystem,whichgenerallyneedstoperformA/Dsamplingontheoutputofthesystem,andthentransferthedatatothesingle-chiporcomputerforalgorithmdataprocessing,andjudgetheexecutionsignalD/Aoutputtomaketheactuatorexecute.Inthisfeedbackprocess,sampling,algorithmprocessingandexecutionobviouslyconsumetoomuchtime,andforsomecomplexcontrolsignals,algorithmdataprocessingrequirementsarehigh,andspecialDSPchipsarerequired,whichiscostly.Therefore,theuseofasingleanalogelectroniccircuittoachieveaclosed-loopcontrolsystemhashigherefficiencyandlowercost.InspiredbytheworkingmodeoftheMC34063step-downcircuit,itisanewdesignideatorealizethechangeoftheAD603gaincontrolvoltagebyusingthecharacteristicsoftheMC34063todynamicallyadjusttheoutputvoltage.Theexperimentalverificationisfeasibleanditissimplerandfasterthantheprogramcontrolmethod.Figure2showstheMC34063step-downcircuit.Figure2MC34063step-downcircuitAsshowninFigure2,theinputis+12V,theoutputis+5V,thereferencevoltageofpin5togroundis+1.25V,theresistanceofpin5togroundisR1=1.2k,andtheoutputandpin5areconnectedtoR2=3.6k,Accordingtotheresistancedividerratio,theoutputisclampedat+5V,thusachievingaregulatedoutput.AppliedinthefieldofAGCcontrol,youcanconnecttheoutputofMC34063tothecontrollergaincontrolterminal,andtheinputtotheoutputterminalofthecontroller.Accordingtoitsworkingprinciple,MC34063collectstheoutputoftheAGCcontrollerandtransmitsittopin5.ItsinternaldynamicallyadjuststhePWMdutycycle,dynamicallychangestheAD603gaincontrolvoltage,andcanavoidtheinterferenceofthesystem,andrealizethefunctionsimilartothePIDalgorithm.Itreplacesthealgorithmicdataprocessingmechanism,whichissimpleandeffective,andhascertainreferencesignificancetothefieldofindustrialautomationcontrol.V.SystemHardwareCircuitDiagramFigure3isthesystemhardwarecircuitdiagram.Thesystemismainlydividedintoinputbufferattenuationcircuit,AD603automaticgainamplifier,outputamplitudedetectorandMC34063feedbackcircuit.Figure3SystemHardwarecircuitdiagram5.1InputBufferAttenuationCircuitBecausetheAD603inputsignalamplitudeVINPislessthanorequalto1.4V,fourdiodeclampsareused.Accordingtotheunidirectionalconductivityofthediodeandtheforwardconductionvoltagedropofsilicon,theinputcharacteristicsarelimitedtomeettherequirementsofAD603.Theinputvoltagerequirements,thefollowerplaystheroleofisolatingthechip.AsshowninFigure3,part①.5.2AD603AutomaticGainAmplifierThe3pinofAD603isthesignalinputterminal,the2and4pinsareconnectedtothegroundwithR4=0,R5=0resistancetomakeitworkmorestable.The5and7pinsareconnectedtotheoutput,whichisthesystemoutputoftheAGCcontroller.Pin1isthegaincontrolvoltageVGterminal,thiscontrolvoltageisconnectedtotheoutputterminalofMC34063,MC34063generatesthecorrespondinggaincontrolvoltageVGaccordingtotheoutputofthesystem.5.3OutputAmplitudeDetectorInthefieldofindustrialcontrol,thesignalisonlyintheformofDC,andtheACsignalalsooccupiesacertainproportion.ForthecontroloftheDCsignal,thesystemoutputcanbedirectlytransmittedtotheMC34063forprocessing,buttheamplitudeoftheACsignalmustbedetected,sothedesignisshowninFigure3inpart③.Commonamplitudedetectors,suchasdioderectifierbridges,areonlysuitableforsituationswheretheinputvoltageisfargreaterthanthediodeconductionvoltagedrop.InAGCcontrol,thesignalinthesystemisoftenlowvoltage,soitcannotbeused,soitisverynecessarytodesignanamplitudedetectorthatcanavoiddiodeconductionvoltagedrop.AfterRCcharging,theDCvoltagevaluewithacertainrelationshipisobtained.InFigure3,thevoltageattheintermediatenodeofR13andR14isUf,andtheexpressionis:Intheformula,UINPistheinputamplitude,V.5.4MC34063FeedbackCircuitTheintermediatenodevoltageUfofR13andR14isproperlycalculatedbyasame-invertingamplifierandanadder,andthenconnectedtopin5ofMC34063.Atthistime,itisclampedat5V,andUf=1Vwhenreversed,thentheAGCcontrollersystemcanbedynamicallymaintainedstabilityofoutputvoltageamplitude.Whenthesysteminputisunstableorthereisnoiseinterference,MC34063dynamicallychangestheoutputvoltagevalueaccordingtotheamplitudedetectionresult,soastoachievethepurposeofchangingthegaincontrolvoltageVG.AsshowninthelowerpartofFigure3,theoutputvoltageofpin2ischargedanddischargedthroughswitchingandspecificSchottkydiodes,andtheattenuatedpartialvoltageistransmittedtopin1ofAD603,whichrealizestheautomaticadjustmentoftheamplificationgainandsuccessfullyrealizestheswitchingpowersupplytechnologyapplicationinthefieldofautomaticcontrolgain.VI.SystemOperationResultsTheexperimentalsettingisthatifthesysteminputsaDCsignal,theoutputwillbeaconstant+1VDC;ifanACsignalisinput,theoutputwillbeanACsignalwithaconstantamplitudeof+1V.Intheexperiment,twoinputmethodsweretestedandverified,andbothmetthedesignrequirements.Table1ispartoftheexperimentaldataoftheinputDCsignal.Intheexperiment,theinputoftheAGCcontrollerisconnectedtothevoltageregulatorsource,andtheinputvoltageiscontinuouslyadjusted.Table2ispartoftheexperimentaldataoftheinputACsignal.Intheexperiment,theAGCcontrollerinputisconnectedtotheUTG9002Csignalgenerator,theamplitudeoftheinputsinewaveiscontinuouslyadjusted,andtheoutputisconnectedtotheoscilloscopetoobservethewaveform.Observationfoundthatnomattertheinputamplitudebecomeslargerorsmaller,theoscilloscopewaveformisbasicallyunchanged.ReadtheoscilloscopewaveformamplitudeandfillinTable2.VII.ConclusionThisarticlesummarizesthedesignoftheAGCcontrollerbasedonAD603andMC34063.ExperimentshaveverifiedthattheAGCcontrolleriseffectiveandmeetsthedesignrequirements.Anewapplicationofswitchingpowersupplychipsinthecontrolfieldisproposed.BecausetheinternalPWMdutycycleisfaster,itcanreplacethetraditionalprogrammableAGCcontroller.Amongthem,MC34063canalsobereplacedbyotherswitchingpowersupplychips.Ithastheadvantagesofuniversalapplicability,simpledesign,lowcost,andithasimportantpracticalvalue.FAQWhatisAD603?AD603isalow-noise,voltage-controlledamplifierforradiofrequency(RF)andintermediatefrequency(IF)automaticgaincontrol(AGC)systems.Itprovidesprecisepin-selectablegain,withagainrangeof-11dBto+31dBat90MHzbandwidth,andagainrangeof+9dBto+51dBat9MHzbandwidth.Anyintermediategainrangecanbeobtainedwithanexternalresistor.Thenoisespectraldensityreferredtotheinputisonly1.3nV/Hz,andthepowerconsumptionis125mWwhenusingtherecommended5Vpowersupply.WhataretheproblemsthatneedtobepaidattentiontowhenusingAD603?Thevoltagecannotbetoohigh.Generally,thevoltageisplusorminus5V,andthemaximumvoltagecannotexceedplusorminus7.5V.Theoutputvoltagecannotexceed2V.Howtosolvetheself-oscillationproblemofAD603?Forhigh-frequencyoperationalamplifiers,thefollowingpointsarethebasicwaystosolveself-excitation.Thepowersupplyisstableandnoripple.Theelectricalconnectionwiresareasshortaspossible.Thead603circuitshouldbefarawayfromthepowercircuit,especiallyawayfromthetransformer.Thepowertransformerandthecircuitboardofad603shouldbeshieldedwithametalboxandgroundedifpossible.Onepointisveryimportant.Foropamps,toolargemagnificationcaneasilycauseself-excitation,soreducethemagnificationasmuchaspossibleandminimizethenumberofmagnificationlevels(generallynotgreaterthan4).Reverseamplificationcansuppressself-excitationinmulti-stageamplification.Ifyouwanttoconnecttothepoweramplifierandthenamplify,itisbesttousetwopowersupplies,andthecircuitshouldbeconnectedtothesameground.WhatisthedifferencebetweenAD603AQandAD603AR?Theirdifferencesareinmodel,Temperature,Package.AD603AQ-40Cto+85C8-LeadCERDIPAD603AR-40Cto+85C8-LeadSOIC_NAfterinputtinganACsignalandbeingamplifiedbyAD603,whydoestheoutputcontainaDCsignal?HowtoeliminatetheDCsignal?WhentheDCblockingcapacitorisnotused,thebiasvoltageoftheinputcircuitneedstobeadjustedforcompensation.IftheDCvoltageoftheACsignalisnotfixed,onlyaDCblockingcapacitorcanbeused,ortheaveragevaluecanbeusedtoeliminateitaftersamplingthenumber.

I.IntroductionForlargesystemssuchasmissileweaponsandequipment,theirperformanceisoftenaffectedbytheexternalenvironmentandtheirownoperatingconditions.Amongthem,theinfluenceoftemperatureoftenplaysaveryimportantrole.Therefore,temperaturedetectionandcontrolhasalwaysbeenthefocusofmanyresearchers.However,sometemperaturemeasurementandcontroldeviceshavelowaccuracyandinaccuratetemperaturecontrol,andsomenewinstrumentsareexpensiveanddifficulttopromote.Itshouldbeparticularlypointedoutthatthetemperaturemeasurementandcontrolsystemdevelopedinthepastisusuallyanindependentsystem,onethingforoneuse,itisdifficulttobeadoptedbyothersystems,andthereareproblemssuchasmaintenancedifficultiesandinconvenience.Tothisend,theauthordevelopedahigh-precisiontemperaturemeasurementandcontroldevicesuitableforresearchanddevelopmentunderlaboratoryconditionsbasedonthecurrentlypopularmodulardesignprinciple.ThedeviceusesanewintegratedtemperaturesensorAD590asthetemperaturemeasurementelement,andprovidestwocontrolunitsforexperimentalcomparison.Bymeasuringandcontrollingthetemperatureinthethermostat,satisfactoryresultshavebeenobtained.CatalogI.IntroductionII.WorkingPrincipleIII.IntegratedTemperatureSensorAD590IV.TemperatureMeasuringBridgeV.PIDRegulatorVI.ProgramDesignVII.ExperimentalAnalysisandConclusionFAQOrdering&QuantityII.WorkingPrincipleFigure1istheelectricalschematicdiagramoftheWCZ-98temperaturemeasurementandcontroldevice.Itsworkingprincipleis:thetemperaturesignaltakenbythetemperaturemeasuringbridgewithAD590asabridgearmisdifferentiallyamplifiedandbufferedandthensentallthewaytothedigitaldisplayfordigitaltemperaturedisplay,andtheotheriscomparedwiththesetvalue.ThecompareddifferenceiscontrolledbyswitchKandcanchoosetosendtotwo-wayadjustmentcontroller.Onerouteiscomposedofacomparisonamplifierandarelay,whichcanbeusedasanadjustmentcontrollertoformanindependenttemperaturemeasurementandcontrolequipmentwithoutconnectingtoacomputer;theotherrouteisaPIDregulator(composedofA/D,D/AandComputercompositionofPIDadjustmentsoftware)andSCRcomposition.Thesignalfromtheregulatingcontrollerrealizestemperaturecontrolthroughthetemperaturecontrolactuator.Figure1ElectricalschematicdiagramoftemperaturemeasurementandcontroldeviceIII.IntegratedTemperatureSensorAD590AD590isadedicatedintegratedtemperaturesensorproducedbyAmericanADcompany,whichbelongstothecurrentoutputtype.Figure2showsthecurrent-voltagecharacteristiccurveofAD590atthreedifferenttemperatures.Inacertaintemperaturerange,itisequivalenttoahighresistancecurrentsource,anditscurrenttemperaturesensitivityislA/K.Itisnotsusceptibletointerferencefromcontactresistance,leadresistance,voltagenoise,etc.Inaddition,italsohasthecharacteristicsofsmallsize,hightemperaturemeasurementaccuracy,goodlinearityandstronginterchangeability.Itisverysuitableforlong-distancemeasurementandcontrol.Itisalsosuitableforthecharacteristicsofmodularandsplitstructurerequiredbythisarticle.Themaintechnicalindicatorsare:Temperaturemeasurementrange:hCurrentoutput(calibrationfactor):lA/K;Powersupplyvoltage:DC4-30V;Linearity:lessthan0.5℃inthefullscalerange;Repeatability:0.1℃;Outputimpedance:about10MQLong-termdrift:0.1℃/monthFigure2I-VcurveofAD590ThecurrentIrflowingthroughtheAD590isasingle-valuedfunctionoftheabsolutetemperatureofitsenvironment,andthemicroampereofIrisequaltotheabsolutetemperatureT,namely:Ir=T10-6A=TA(1)IV.TemperatureMeasuringBridgeFigure3istheschematicdiagramofthetemperaturemeasurementbridge.ThevoltageformedonthecurrentIiR2andRw2flowingthroughtheAD590is:Ul=Ii(R2+Rw2)(2)Figure3SchematicdiagramoftemperaturemeasuringbridgeByadjustingRw2tomake(R2+Rw2)equalto10K,substitutingformula(1)intoformula(2),wecanget:U1=Ii(R2+Rw2)=T10-2V(3)U2=2.732VbyadjustingRwl.Thentheoutputofthebridgeis:UAB=U1﹣U2=T10-2﹣2.732=(T﹣273.2)10-2V(4)BecauseTistheabsoluteambienttemperaturemeasuredbyAD590,aftersubtracting273.2fromit,theCelsiustemperaturetcanbeobtained,namely:UAB=t10-2V(5)Atthispoint,thetemperaturemeasuringbridgeconvertstheambienttemperatureintoavoltagevaluethatisproportionaltothetemperatureinCelsius.V.PIDRegulatorOneoftheadjustmentcontrollersofthetemperaturemeasurementandcontroldeviceusesaPIDregulator(proportionalintegralderivativeregulator),whichcandeterminethesizeofthecontrolquantityaccordingtotheproportionalvalue,integralvalue,andderivativevalueofthedifferencebetweenthetemperaturesetvalueandtheactualvalue.Thetemperaturemeasurementandcontroldeviceadoptstheoutputfeedbacktypecontrol.Extractingthispartfromthegeneralprinciplediagram,youcangetthePIDcontrolprinciplediagramasshowninFigure4.Inthefigure,UdandUarethesetvalueandactualvalueofthethermostatrespectively,theerrore=Ud﹣KT,Kisthemagnificationofthemeasuringtransducer,andYistheadjustmentvalueofthePIDoutput.Figure4PIDcontrolprinciplediagramThesimulationexpressionofPIDalgorithmis:Intheformula,Y(t):regulatoroutputvalue;E(t):inputdeviation;KP:regulatorproportionalcoefficient;Tl,TD:verseunitintegral,derivativetimeAfterdiscretizingequation(6),thePIDincrementalcontrolequationisobtained:Intheformula,theintegralcoefficientKl=KPT/T1,thedifferentialcoefficientKD=KPTD/r,andTisthesamplingperiod.thenapply(7)toZ-transform,andget:Intheexperiment,theauthorusedastepsignaltoroughlymeasuretheresponseintheopen-loopstate.Fromthestepresponsecurve,itisknownthatthethermostatisafirst-orderinertialinkplusapuretimedelaylink,namely:Thelagtimerofthesystemisdeterminedtobeapproximately20seconds,andthetargettimeconstantTPisapproximately50seconds.Selectthecontroldegreetobe1.5,accordingtothestepresponsecurvetuningparametermethod(refertoliterature[1]),obtain:T=0.34z=6.8sKr=0.85Tr,/r=2.125T1=1.62r=32.4sTD=0.65r=13sSubstitutingtheabovevalueforequation(9),wecanobtain:Q0=6.41Q1=-5.96Q2=4.06TheequationofPIDregulatoris:VI.ProgramDesignThePIDcontrolprogramflowoftheWCZ-98temperaturemeasurementandcontroldeviceisshowninFigure5.ThebasicideaisthesameasthegeneralPIDcontrolflow.Itsnoneedtorepeathere.Figure5PIDcontrolprogramflowchartVII.ExperimentalAnalysisandConclusionPutthetemperaturemeasurementandcontroldeviceintoathermostatwithanexternaldimensionof248208262(mm).Thethermostatuses50mmthickpolystyreneastheheatinsulationmaterialandwaterasthemedium.Theheatingdeviceiscomposedof2SRS3-220/0.5heatingtubesandauxiliarypartstopreventleakage.Thetemperaturecanbepresetoutsidethethermostatandthereisaswitchtoselectthetypeofcontroller.Throughexperiments,comparingthecontroleffectsofthetwoadjustmentcontrolmethods,wefoundthatthetemperatureoftheadjustmentcontrollercomposedofacomparisonamplifierandarelayisnotstableduringthetemperaturecontrolprocessandalwaysfluctuateswithinacertainerrorrange.ThetemperaturecontrolperformanceoftheregulatingcontrollercomposedofPIDregulatorandthyristorisverygood.Takingtemperaturecontrolof60Casanexample,thetemperaturechangecurveobtainedbytheexperimentisshowninFigure6.Figure6PIDtemperaturecontrolexperimentresultcurveItcanbeseenthattheuseofanalogcircuitsforadjustmentandcontrolisbeneficialtomakethemeasurementandcontroldeviceanindependentinstrument(noneedtoconnecttoacomputer),anditstemperaturemeasurementandcontrolaccuracycanmeetthegeneralrequirements;andthroughPIDcontrol,itsprecisionoftemperaturemeasurementandcontrolisveryhigh.Itisusedinconjunctionwiththethermostatandtheself-developedSYZJX-2experimentaladapterbox.TheanaloginputboardPCL-818LandtheanalogoutputboardPCL-726areconnectedtothecomputertoachievehigh-precisiontemperaturecontrol.FAQWhatisAD590?AD590isatemperaturesensor,thecurrentoutputsensitivityis1A/℃,thestandardoutputvalueis298.2Aat25℃,andtheworkingvoltagerangeis4~30V.WhatarethecharacteristicsofAD590temperaturesensor?Singlefunction(onlytemperaturemeasurement),smalltemperaturemeasurementerror,lowprice,fastresponsespeed,longtransmissiondistance,smallsize,micropowerconsumption,etc.Itissuitableforremotetemperaturemeasurementandtemperaturecontrolwithoutnon-linearcalibration.Theperipheralcircuitissimple.HowtodetectthequalityofAD590?AD590hasacurrentof273mAat0.Because2113isaWensensitiveresistor5261,itmeansthatitisgreatlyaffectedbythesurroundingtemperature4102.Itisverydifficulttomeasurewithoutrelyingon1653othertools.Giveyousomesuggestions.Whentheambienttemperaturerisesbyonedegree,thecurrentofAD590increasesby1uA.WhatyouhavetodoistoworkwithAD590simultaneouslywiththehelpofahigh-precisiontemperaturetestinstrument.AfterAD590series10Kresistance,measureitsvoltage,thatistosay,itshouldbe2.73Vat0,and2.98Vatroomtemperature25.Forhigheraccuracy,itisrecommendedthatyouusetheelectronicbuildingblocksoftwareArdunioformeasurement,andputthecorrespondingdataintoMATLABforlinearregression.Thebetterthelinearity,themorestablethemeasurement.AD590isnotahigh-precisiontemperaturetestingdevice.Ifhigh-precisiontestingisrequired,othercomponentsarerecommended.WhatisthedifferencebetweenAD590andPT100?AD590isacurrent-typetemperaturesensor.Itconvertstemperaturechangesintocurrentconversion.Thesimplestprocessingistopassaresistor(10K)aftertheoutputtoconvertthecurrentintoavoltage,andthenthroughthedetectionvoltage,thecurrentatthistimecanbededuced.Usetherelationshipbetweencurrentandtemperatureinthesensordatatocalculatethecurrenttemperature.PT100isaresistancetypetemperaturesensor,whichconvertstemperaturechangesintoresistancechanges.ThesimplestprocessistoplacePt100inabridge,usethevoltagedifferenceatthemidpointofthebridgearm,anduseadifferentialamplifiercircuit(instrumentamplifiercircuit)Amplifythevoltage,usetheamplifiergainandbridgestructuredata,andusethedetectedvoltagetoinverselycalculatethecurrentresistancevalue,andusetherelationshipbetweenresistanceandtemperatureinthePT100datasheettocalculatethecurrenttemperature.IsAD590athermocoupleorathermalresistance?Itisneitherathermocouplenorathermalresistance.Themainprincipleistodetectthetemperatureaccordingtothetemperaturechange,theoutputcurrentchange,andthecurrentsize.IDescriptionFirst,thisblogwillintroducethe1wiredigitaltemperaturesensorDS18B20.Wemainlyintroduceitsstructure,characteristicsandworkingprinciplehere.Second,wewillintroduceatemperaturemeasurementsystembasedonDS18B20andAT89S52microcontroller.Herewemainlyintroduceitshardwarestructureandassembler.Third,therewillbepartofthesourceprogramthatisdetailedanalyed.Finally,theblogalsoexplainshowitperformstemperaturemeasurementintheagriculturalfield.Thetemperaturemeasuringdevicehasaseriesofadvantages.Suchas:highdisplayaccuracy,lowprice,simplestructure,convenientexpansionandwideapplication.DS18B20TemperatureSensorTutorialCatalogIDescriptionIIIntroductionIIIDS18B20Overview3.1DS18B20Advantages3.2DS18B20Features3.3DS18B20InternalStructureIVDS18B20MCUTemperatureMeasurementDevice4.1CompositionofSystemHardware4.2DesignofInterfaceVSoftwareDesignVIApplicationinAgriculturalProduction6.1TemperatureofMildew6.2TemperatureofAgriculturalProducts6.3TemperatureDetectioninGreenhouses6.4TemperatureofSoilVIIConclusionFAQOrdering&QuantityIIIntroductionWhatistemperature?Whataretherolesoftemperature?Temperatureisaphysicalquantitythatcharacterizesthedegreeofcoolingofanobject,anditisalsoabasicenvironmentalparameter.Inagro-industrialproductionanddailylife,themeasurementandcontroloftemperaturealwaysoccupyanextremelyimportantposition.Atpresent,atypicaltemperaturemeasurementandcontrolsystemconsistsofthefollowingparts:Analogtemperaturesensor;A/Dconversioncircuit;MCU.However,theanalogsignaloutputbytheanalogtemperaturesensorhastobeconverted.Itcaninterfacewithmicroprocessorssuchassingle-chipmicrocomputersonlyafterobtainingdigitalsignalsthroughtheA/Dconversionlink.Therefore,thehardwarecircuitstructureiscomplicatedandthecostishigh.ButDS18B20canhelpsolvethisproblem.Thenew1wiredigitaltemperaturesensorrepresentedbyDS18B20integratestemperaturemeasurementandA/Dconversion,anddirectlyoutputsdigitalquantities.Thestructureoftheinterfacecircuitwiththesingle-chipmicrocomputerissimple,anditiswidelyusedintheoccasionswithlongdistanceandmanynodes.Therefore,DS18B20hasstrongpromotionandapplicationvalue.IIIDS18B20Overview3.1DS18B20AdvantagesDS18B20type1wireintelligenttemperaturesensorproducedbyDALLASSemiconductorCompany.Itbelongstoanewgenerationofintelligenttemperaturesensorsadaptedtomicroprocessors.Comparedwiththetraditionalthermistor,ithasthefollowingadvantages:Itcandirectlyreadthemeasuredtemperature;Thereadingmodeof9-12digitscanberealizedthroughsimpleprogrammingaccordingtoactualrequirements;Itcanalsocomplete9-bitand12-bitdigitalquantitieswithin93.75msand750ms,respectively,withamaximumresolutionof0.0625C;ToreadorwritetheinformationofDS18B20,onlyoneportline(1wireinterface)isrequiredtoreadandwrite.3.2DS18B20FeaturesUnique1-WireInterfaceRequiresOnlyOnePortPinforCommunicationReduceComponentCountwithIntegratedTemperatureSensorandEEPROMMeasuresTemperaturesfrom-55Cto+125C(-67Fto+257F)0.5CAccuracyfrom-10Cto+85CProgrammableResolutionfrom9Bitsto12BitsNoExternalComponentsRequiredParasiticPowerModeRequiresOnly2PinsforOperation(DQandGND)SimplifiesDistributedTemperature-SensingApplicationswithMultidropCapabilityEachDeviceHasaUnique64-BitSerialCodeStoredinOn-BoardROMFlexibleUser-DefinableNonvolatile(NV)AlarmSettingswithAlarmSearchCommandIdentifiesDeviceswithTemperaturesOutsideProgrammedLimitsAvailablein8-PinSO(150mils),8-PinSOP,and3-PinTO-92Packages3.3DS18B20InternalStructureDS18B20adopts3-pinPR-35packageor8-pinSOICpackage.ItsDS18B20externalshapeandpindiagramareshowninFigure1.TheDS18B20internalstructureblockdiagramisshownasinFigure2.Thestructureof64-bitflashROMisshowninFigure3.Figure1.DS18B20PinoutFigure2.DS18B20InternalStructureFigure3.64bFlashROMStructureIVDS18B20MCUTemperatureMeasurementDevice4.1CompositionofSystemHardwareTheDS18B20single-chipmicrocomputerintelligenttemperaturemeasurementdeviceismainlycomposedofDS18B20temperaturesensor,AT89S52,displaymoduleandpowermodule,asshowninFigure4.Themaintechnicalindicatorsoftheproductare:MeasuringRange(℃):-55.0~+125.0MeasurementAccuracy(℃):0.1ResponseTime(s):1.5Figure4.SystemStructureDiagramThesystemusesDS18B20asatemperaturesensor.Theone-chipcomputerAT89S52ofATMELCompanyservesastheprocessor.Temperaturedisplayandlight-emittingdiodeastemperaturecontroloutputunit.Thewholesystemstrivestohaveasimplestructureandperfectfunctions.Theworkingprincipleofthesystemisasfollows:AfterDS18B20carriesonthefieldtemperaturemeasurement,themeasureddataissenttotheP3.5portofAT89S52.Thetemperaturevalueisdisplayedafterbeingprocessedbythemicrocontroller.Then,thistemperaturevalueiscomparedwiththeupperlimitofthesetalarmtemperature.Ifitishigherthanthesetupperlimit,theyellowLEDlightsup.ThemaincircuitdiagramofthesystemisshownasinFig.5.Figure5.DS18B20TemperatuerMeasurementDevice4.2DesignofInterfaceThereare2waystoconnectDS18B20tothehardwareofthemicrocontroller:Vccisconnectedtoexternalpowersupply,GNDisgrounded,andI/OisconnectedtotheI/Olineofthemicrocontroller;Useparasiticpowersupply,UDDandGNDaregroundedatthistime,andI/OisconnectedtoMCUI/O.Regardlessofthe1stor2ndpowersupplymode,theI/Olinemustbeconnectedtoapull-upresistorofabout4.7k.Figure6showsatypicalconnectionbetweenDS18B20andamicroprocessor.InFigure6(a),DS18B20adoptsparasiticpowersupply,anditsVDDandGNGterminalsarebothgrounded;InFigure6(b),theDS18B20usesanexternalpowersupply,anditsVDDterminalusesa3~5.5Vpowersupply.ThissystemadoptsthewiringmodeshowninFigure6(b),thatis,theworkingmodeofexternalpowersupply.TheactualconnectionpictureofthesystemisshowninFigure6.Figure6.PhysicalDiagramofSystemConnectionVSoftwareDesignItisworthnotingthatDS18B20hasveryhighrequirementsontwoaspects:timingandelectricalparameters.Therefore,theworkflowofthemainCPUaccessingtheDS18B20throughthesingle-businterfacemustfollowastrictoperatingsequence:first,initializetheDS18B20;second,sendROMcommands;andthen,sendfunctioncommands.Wecantakealookatthefollowingpartofthesourceprogramisasfollows:ORG0000HAJMPMAIN;StatementofMCUmemoryallocation!TEMPER_LEQU29H;usedtosavethelower8bitsofthereadtemperatureTEMPER_HEQU28H;usedtosavetheupper8bitsofthereadtemperatureFLAG1EQU38H;WhethertheDS18B20flagisdetectedPNFLAGEQU68H;DatapositiveandnegativeflagA_BITEQU20H;thesingledigitofthedigitaltubestoresthememorylocationB_BITEQU21H;ThetendigitsofthedigitaltubestorethememorylocationC_BITEQU22H;ThedecimalplacesofthedigitaltubestorethememorylocationT_INTEGEREQU26H;TheintegerpartafterFORMAT,whichintegratestwobytesoftemperatureintoonebyteT_DFEQU27H;ThedecimalfractionafterFORMAT,thedecimalfractionofnibbletemperature(therearelowfourdigits)MAIN:LCALLGET_TEMPER;CallthetemperaturereadingsubroutineLCALLT_FORMAT;Formattheread2bytetemperatureLCALLALARM;callthealarmsubroutineLCALLDISPLAY;callthedigitaltubedisplaysubroutineLCALLD1S;testafteradelayof0.5secondsAJMPMAIN;thisistheDS18B20resetinitializationsubroutineINIT_1820:SETBP3.5NOPCLRP3.5;thehostsendsoutaresetlowpulsewithadelayof537microsecondsMOVR1,#2TSR1:MOVR0,#250DJNZR0,$DJNZR1,TSR1SETBP3.5;thenpullupthedatalineNOPNOPNOPMOVR0,#25HTSR2:JNBP3.5,TSR3;waitingforDS18B20responseDJNZR0,TSR2;delayLJMPTSR4TSR3:SETBFLAG1;SettheflagbittoindicatethatDS1820existsLJMPTSR5TSR4:CLRFLAG1;cleartheflagbit,indicatingthatDS1820doesnotexistLJMPTSR7TSR5:MOVR0,#120TSR6:DJNZR0,TSR6;timingrequiresaperiodofdelayTSR7:SETBP3.5RET;readthetemperaturevalueafterconversionGET_TEMPER:;SETBP3.5LCALLINIT_1820;firstresetDS18B20JBFLAG1,TSS2RET;DeterminewhetherDS1820exists?IfDS18B20doesnotexistThenreturnTSS2:MOVA,#0CCH;skipROMmatchingLCALLWRITE_1820MOVA,#44H;IssuetemperatureconversioncommandLCALLWRITE_1820LCALLDISPLAYLCALLINIT_1820;resetbeforereadingtemperatureMOVA,#0CCH;SkipROMmatchingLCALLWRITE_1820MOVA,#0BEH;IssuereadtemperaturecommandLCALLWRITE_1820LCALLREAD_18200;savethereadtemperaturedatato28H/29HRET;WriteDS18B20subroutine(withspecifictimingrequirements)WRITE_1820:MOVR2,#8;atotalof8bitsofdata;CLRCWR1:CLRP3.5MOVR3,#6DJNZR3,$RRCAMOVP3.5,CMOVR3,#23DJNZR3,$SETBP3.5NOPDJNZR2,WR1SETBP3.5RET;readtheprogramofDS18B20,readtwobytesoftemperaturedatafromDS18B20READ_18200:MOV36H,#2;SetthehighandlowtemperatureReadfromDS18B20MOVR1,#29H;thelowbitisstoredin29H(TEMPER_L),thehighbitDeposit28H(TEMPER_H)RE00:MOVR2,#8;Thereare8bitsofdataRE01:;CLRCSETBP3.5NOPNOPCLRP3.5NOPNOPNOPSETBP3.5MOVR3,#9RE10:DJNZR3,RE10MOVC,P3.5MOVR3,#23RE20:DJNZR3,RE20RRCADJNZR2,RE01MOV@R1,ADECR1DJNZ36H,RE00RET;-----Integratethetwo-bytetemperaturereadout(pleaserefertotheinformationaboutthe2-bytetemperatureformatreadoutbyDS18B20)----------T_FORMAT:;AlarmsubroutineALARM:;DisplaysubroutineDISPLAY:;1MSdelay(calculatedby12MHZ)D1MS:MOVR7,#250llmm:nopnopDJNZR7,llmmRET;1MSdelay(calculatedby12MHZ)D1S:MovR6,#4LOOP2:movR5,#125;------------250LOOP1:LCALLD1mSDJNZR5,LOOP1DJNZR6,LOOP2RET;7-segmentdigitaltube0-9digitcommonanodedisplaycodeNUMTAB:DB0C0H,0f9H,0a4H,0b0H,99H,92H,82H,0f8H,80H,90H,0ffHXIAOSHU:DB00H,01H,01H,02H,03H,03H,04H,04H,05H,06H,06H,07H,08H,08H,09H,09HENDVIApplicationinAgriculturalProductionThistemperaturemeasurementsystemcandirectlyoutputdigitalquantities.Inaddition,ithasthecharacteristicsofsimplestructure,convenientuseandlowprice.Therefore,itcanbewidelyusedinagriculturalproduction.6.1TemperatureofMildewModerngrainwarehousescanusethissystemtomonitorthetemperatureofhundredsofpoints.Inthisway,youcaneasilygraspthetemperaturechangesatvariouspointsatdifferenttimes,increasestoragecapacity,andeffectivelyreducetheoccurrenceofmildew.6.2TemperatureofAgriculturalProductsAtpresent,low-temperaturerefrigerationmeasuresarewidelyadoptedforthepreservationoffruitsandvegetables.Thesystemcanbeinstalledinthetemperaturemeasurementpositionoftherefrigeratorcompartment.Inthisway,thetemperaturevaluecanbeconvenientlyobservedatanytimetocheckwhethertheoptimalpreservationtemperatureisreached.6.3TemperatureDetectioninGreenhousesThesystemisusedinplasticgreenhousesforgreenhousevegetablecultivationandflowerproduction.Inthisway,automatictemperaturedisplaycanberealized,andlaborandtimefortemperaturemeasurementcanbesaved.6.4TemperatureofSoilIntheprocessofplantingcropswithstrictrequirementsonsoiltemperature,thesystemcantestthechangesinsoiltemperatureasneededtofacilitatethegraspofaccuratetemperaturevalues.VIIConclusionThesingle-chiptemperaturemeasurementsystemtakesfulladvantageofthesimplicityofthehardwarestructureofDS18B20andAT89S52,using8-segmentdigitaltubedisplay,lowpriceandwideapplication.Accordingtoactualneeds,wecanalsouseLCDasadisplaydeviceorformadistributedtemperaturemeasurementandcontrolsystem.Althoughthedesigniseasytoexpand,italsohasitsshortcomings.Thesimplicityofthehardwarestructurecomesattheexpenseofsoftware.Therefore,specialattentionshouldbepaidtotheworkingsequencerequirementsofDS18B20duringprogramming.Inshort,thesystemcanbewidelyusedintemperaturemeasurementinagriculturalproduction.FAQWhatisDS18B20temperaturesensor?TheDS18B20isa1-wireprogrammabletemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.HowdoestheDS18B20work?Itworksontheprincipleofdirectconversionoftemperatureintoadigitalvalue.IsDS18B20athermistor?Athermistorisathermalresistor-aresistorthatchangesitsresistancewithtemperature....Thermistorshavesomebenefitsoverotherkindsoftemperaturesensorssuchasanalogoutputchips(LM35/TMP36)ordigitaltemperaturesensorchips(DS18B20)orthermocouples.HowaccurateisDS18B20?TheDS18B20readswithanaccuracyof0.5Cfrom-10Cto+85Cand2Caccuracyfrom-55Cto+125C.Whatisds1820?TheDS18B20isonetypeoftemperaturesensoranditsupplies9-bitto12-bitreadingsoftemperature....Thecommunicationofthissensorcanbedonethroughaone-wirebusprotocolwhichusesonedatalinetocommunicatewithaninnermicroprocessor.HowdoIconnectmyDS18B20tomyRaspberryPi?OnceyouveconnectedtheDS18B20,powerupyourPiandlogin,thenfollowthesestepstoenabletheOne-Wireinterface:1.Atthecommandprompt,entersudonano/boot/config.txt,thenaddthistothebottomofthefile:2.dtoverlay=w1-gpio.3.ExitNano,andrebootthePiwithsudoreboot.WhatistheworkingprincipleofDS18B20?TheDS18B20DigitalThermometerprovides9to12-bit(configurable)temperaturereadingswhichindicatethetemperatureofthedevice.Itcommunicatesovera1-Wirebusthatbydefinitionrequiresonlyonedataline(andground)forcommunicationwithacentralmicroprocessor.Inadditionitcanderivepowerdirectlyfromthedataline(parasitepower),eliminatingtheneedforanexternalpowersupply.ThecorefunctionalityoftheDS18B20isitsdirect-to-digitaltemperaturesensor.Theresolutionofthetemperaturesensorisuser-configurableto9,10,11,or12bits,correspondingtoincrementsof0.5C,0.25C,0.125C,and0.0625C,respectively.Thedefaultresolutionatpower-upis12-bit.WheretouseDS18B20Sensor?TheDS18B20isa1-wireprogrammableTemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.Itcanmeasureawiderangeoftemperaturefrom-55Cto+125withadecentaccuracyof5C.EachsensorhasauniqueaddressandrequiresonlyonepinoftheMCUtotransferdatasoitaverygoodchoiceformeasuringtemperatureatmultiplepointswithoutcompromisingmuchofyourdigitalpinsonthemicrocontroller.HowconnectDS18B20toArduino?FirstplugthesensoronthebreadboardtheconnectitspinstotheArduinousingthejumpersinthefollowingorder:pin1toGND;pin2toanydigitalpin(pin2inourcase);pin3to+5Vor+3.3V,attheendputthepull-upresistor.OnanATMega328P,whyisaDS18B20temperaturesensorreturningincorrecttemperaturevalues?Severalpossibilities:1.Ifitisjustreadingalittlehigh,itmightbecausedbyselfheating.Addaheatsinkand/ormakemeasurementslessfrequently.2.Especiallyifthevaluesarereallywhacky,itmightbecodewitherrorsormis-wiring.Useapublishedsketchtocheckoperation.3.TheDS18B20mightbedefective.Tryanother.4.Itsaccurateto0.5C.Areyouexpectingittobemoreaccurate(likedowntotheLSBofthereadvalue)?

IDescriptionThisblogintroducesandanalyzes4simpleandeasy74LS00NandGatecircuitdiagrams.Itsincluding:SquareWaveGeneratorCircuit,PulseGeneratorCircuit,LEDLightCircuit.Andintheend,wewillanalyzethecircuitthatturnsthetimerintoacountdowntimerindetail.ThisVideoisAnIntroductionof7400LogicDevicesCatalogIDescriptionIISquareWaveGeneratorCircuitIIIPulseGeneratorCircuitIVLEDLightCircuitVTurnTimerintoCountdownTimer5.1SchemeDesign5.2ImplementationofSchemeDesignOrdering&QuantityIISquareWaveGeneratorCircuitLetstakealookatthefigurebelow.Itsasquarewavegeneratorcircuit.Thiscircuitcontainsa74LS00NandGateintegratedcircuit.Figure1.SquareWaveGeneratorCircuitDiagramAmongthiscircuitdiagram:NANDgates1,2andexternalRCtimeconstantcomponentsformanoscillatorcircuitNANDgate3isabufferoutputstage.AslongasthecapacityofCischanged,squarewaveoutputsofdifferentfrequenciescanbeobtained.IIIPulseGeneratorCircuitFigure2.PulseSignalGeneratorCircuitDiagramThecircuitdiagramisshowninFigure2anditsasimplepulsesignalgeneratorcircuit.ThesignalgeneratormainlyusestwoTTLintegratedcircuits(74LS00and74LS221).Sowhychoosethesetwocircuits?Thatisbecause,thesetwocircuitscanbeusedtogenerateapulsesignalof=4s.Besides,itusesfewercomponentsandisconvenientfordebuggingandmaintenance.IVLEDLightCircuitThiscircuitismadewithNE555,74LS00,74LS154,74LS193andLEDlights,andtheproductionprocessisverysimple.Whenweturnonthepower,hereishowitworksis:WhentheoutputQ0ofthe74LS154decoderislow,the74LS193isapositivecounter.Atthistime,theLEDsareindividuallylitfromD1...D16;WhentheoutputQ15ofthe74LS154decoderislow,the74LS193isacountdowncounter.Atthistime,theLEDsareindividuallylitfromD16...D1.Figure3.LEDLightCircuitDiagramFromtheabovewecanseethat:theLEDlightsturnonfromD1toD16,andthenbacktoD1fromD16,andsoon.VTurnTimerintoCountdownTimerGenerally,therearetwodesignideasforturningatimerintoacountdowntimer:First,changethecountingchipinthetimer;Second,resetthefunctionofthechip.Besides,thereisactuallyanotherwaytoachievethisgoal:Byappliyingthe74LS00and74LS20chipstoreversetheresultsonthedisplay,soastoachievethepurposeofcountingdown.5.1SchemeDesignTheresultdisplayedbyeachdigitofthetimerisanincrementalvalue,suchas0.1.2.3.4.5.6.7.8.9.Yet,thecountdowntimerdisplaysadecreasingvalue,suchas9.8.7.6.5.4.3.2.1.0.Aslongasthedisplayresultconversioniscompletedwithasuitablelogiccircuit,thetimercanbeturnedintoacountdowntimer.Atfirst,weneedtofindthelogicalrelationshipbetweenthetimerdisplayresultandthecountdowntimerdisplayresult.Table1belowliststheBCDcodescorrespondingtoeachdisplayresultofthetimerandcountdowntimer.Fromthistable,youcaneasilyfindtheBCDcodesofthetimerandcountdowntimer:ThelowestbitQ1andY1areopposite;WhileQ2andY2arethesame;RelationshipbetweenQ3andY3:Y3ofthecountdowntimeristheexclusiveORoftimerQ3andQ2;RelationshipbetweenQ4andY4:TheY4bitofthecountdowntimeristheoppositevalueoftheORofQ4,Q3,andQ2ofthetimer,whichisalsoequaltothenon-re-ANDofQ4,Q3,andQ2.Table1.CorrespondingBCDCodeDisplayedby(Down)TimerTheabovelogicalexpressionis:Therefore,aslongasyouchooseacircuitthatcancompletetheabovelogicconversionrelationship,youcanrealizethedesignfromatimertoacountdowntimer.Thefigure?showsatwo-digittimercircuit.Afteraddingtheaboveconversioncircuit,itbecomesthefigure3showsthecountdowncircuit.Figure4.TimerCircuitDisplaying2DigitsFigure5.CountdownCircuitDiagram5.2ImplementationofSchemeDesignTwokindsofchips74LS00and74LS20areuesdhere.Theformerarefourtwo-inputNANDgates,whichareusedtocompletetheconversionofY1andgeneratethenegationofQ4,Q3,andQ2.Thelatteraretwofour-inputNANDgates,whichareusedtoobtainY4fromthenon-reANDofQ4,Q3,andQ2.Insummary,wecanfollowthelogicalrelationshipasfollows:ThelogicdiagramisshowninFigure6.Figure6.LogicDiagramKnowingthattheXORgateoperationcanbecompleted,theY3conversioncanbecompleted.Theconnectioncircuitdiagramoftheabove-mentionedY4,Y3,Y1conversionspecificphysicalobjectsisshowninFigure7.Figure7.Y4,Y3,Y1ConversionSpecificPhysicalConnectionDiagramFigure8showstheactualpictureofthecountdowntimer.Figure8.CountdownTimerSofar,thetimerhasbecomeacountdowntimer.Throughthisdesignmethod,thereisnoneedtochangetheoriginalcountercircuit,isitparticularlytrouble-free?I.IntroductionTDA7294isaveryinnovativeDMOShigh-powerintegratedamplifiercircuitlaunchedbythefamousEuropeanSGS-THOMSONSTMicroelectronicstomainlandChinainthe1990s.Itsweepsawaytheraw,cold,andhardtonesofthepreviouslinearintegratedpoweramplifiersandthickfilmintegration,andiswidelyusedintheHI-FIfield:suchashometheater,activespeakers,etc.Thedesignofthischipfocusesontone,andhastheadvantagesofbipolarsignalprocessingcircuitandpowerMOS.Ithasthecharacteristicsofhighvoltageresistance,lownoise,lowdistortion,andveryaffinityforreplayingsound;andhasasilentstandbyfunction,short-circuitcurrentandoverheatprotectionfunctionstomakeitsperformancemoreperfect.ThisarticlewillintroduceseveralpoweramplifiercircuitdesignsbasedonTDA7294.CatalogI.IntroductionII.OCLCircuitIII.BTLCircuitIV.ConstantCurrentPowerAmplifierV.Hi-FiIntegratedPowerAmplifierVI.ActiveSubwooferAmplifierAddsStandbyFunctionVII.HighFidelityPowerAmplifierVIII.ClassABPowerAmplifierIX.Two-channelPowerAmplifierX.100WPowerAmplifierCircuitOrdering&QuantityII.OCLCircuitTheOCLcircuitdiagramisshowninFigure1.Thiscircuitisadual-channel70WpoweramplifiercomposedoftwoTDA7294.Therearefewexternalcomponentsandsimplecircuit.Whenthepowersupplyvoltageis35V,70Wcontinuousoutputpowercanbeobtainedonan8ohmload.Itisverysuitableforplaybackinanenvironmentbelow30squaremeters.Ifthespeakerimpedanceislessthan8ohms,thepowersupplyvoltageshouldbereducedaccordingly.Figure1OCLCircuitDiagramIII.BTLCircuitTheBTLcircuitisshowninFigure2.ItusestwoTDA7294bridgestoformaBTLpoweramplifiercircuit.Theoutputpowercanreachmorethan150W.Itissuitableforplacesthatrequirehighpowersuchasdancehalls.4TDA7294arerequiredforstereo.Whenthepowersupplyvoltageis25V,acontinuousoutputpowerof150Wcanbeobtainedonan8ohmload.Whenthepowersupplyis35V,acontinuousoutputpowerof180Wcanbeobtainedona16ohmload.WhenuseTDA7294asBTLpoweramplifier,theloadmustnotbelessthan8ohms.Figure2BTLCircuitDiagramIV.ConstantCurrentPowerAmplifierThispoweramplifiercircuitissomewhatdifferentfromtheprevioustwostructures.Itsfeedbackcircuitiscurrentsampling,voltagesummationandnegativefeedback.Thiskindofcircuitstructureistheconstantcurrentpoweramplifierthatpeopleoftensay.Thespecificanalysisofthecircuitwillnotbedetailed,onlythemoreprominentadvantagescomparedwiththetraditionalconstantvoltagepoweramplifierwillbeintroduced.(1)Theoutputcurrentofthepoweramplifierhasnothingtodowiththeloadimpedance.Eveniftheloadisshort-circuited,itwillnotcausetheamplifiertooverheat.(2)Theoutputpowerincreaseswiththeincreaseofloadimpedance.Pushingthespeakerloadwithinacertainpowerreservecanensurethebassstrengthandhighfrequencyresolutionoftheoriginalmusicsignal.(3)Theforceactingonthevoicecoilofthespeakeronlydependsonthecurrent.Theuseoffluid-controlledoscillationtopromotethespeakermustbefasterthanthevoltage-controlledoscillation,sothattheinputandoutputimpedanceofthespeakervibrationsystemcanbeeasilymatched.Theconstantcurrentpoweramplifiercircuitisactuallyacontrolledcurrentsourcecontrolledbytheinputsignalvoltage.Itsinternalfeedbackcircuitiscurrentsampling,voltagesummingnegativefeedback,andithasthecharacteristicsofhighinputandoutputimpedance.Theinputimpedanceishigh,whichisexactlywhatthepreviousstageconstantvoltageamplifiercircuitneeds,whichisbeneficialforthesignalvoltagetobesenttotheinputendofthepoweramplifierwithoutloss.Thehighoutputimpedancecanreducetheshuntoftheinternalresistancetothesignal,whichisconducivetoaddingtheoutputsignalcurrenttotheload.InFigure3,thepowersupplyvoltageisselectedas35V,anditsmagnificationisdeterminedbytheratioofthespeakertoR6.Figure3ConstantcurrentpoweramplifiercircuitdiagramV.Hi-FiIntegratedPowerAmplifierThefamousEuropeanSGS-THOMSONSTMicroelectronicshaslaunchedaHi-Fihigh-powerDMOSintegratedamplifiercircuitTDA7294.ThecircuitisshowninFigure4.Itintegratesthebestdesignofmodernpoweramplifiercircuit,combinestheadvantagesofbipolarsignalprocessingcircuitandpowerMOS,hasthecharacteristicsoflownoiseandlowdistortion;standbyandmutecircuitcompletelyeliminatestheimpactnoisecausedbypoweronandoff,andeliminatesspeakerprotectioncircuitoverheating,short-circuitcurrentprotectionandotherfunctionsmakeitsperformancemoreexcellent.ThisdeviceissuitableforhometheaterandHi-Fiamplifiers.Themainparametersare:VS(powersupplyvoltage)10~40V(maximumvoltagewithoutsignal50V);Io(peakoutputcurrent)10A;Po(RMScontinuousoutputpower)70Wwhenvs=35V8;vs=70Wwhen27V4;(effectivevalueofmusicoutputpower)100WwhenVS=38V8;100WwhenVS=29V4.Figure4Hi-FiIntegratedPowerAmplifierCircuitDiagramTheclosed-loopgainofthecircuitinFigure4is30dB.IncreasingR3canincreasethegain,andviceversa,buttheamplifiergainshouldbe24dB.TheamplifierhasthebestperformancewhenR1=R3.R7,C4andR5+R6,C3determinethestandbyandmutetimeconstants.Thelargerthevalue,thelongerthetime.Whenthecontrolterminalisconnectedtolowpotentialground,itismuteandstandby;whenthecontrolterminalisconnectedtoVS,because(R5+R6)R7,pin⑩risestoahigherpotentialthanpin⑨,andturnstoalowpotentialfirstwhenshuttingdown,whichmakesthestandbyandshutdownprocessesgooninasilentstate,ensuringthattheamplifieristurnedonandoffwithoutnoise.Figure5BTLPoweramplifierfinishedboardForhigh-powerprofessionalapplicationsfiledssuchasdancehalls,youcanchoosetheBTLpoweramplifierfinishedboardshowninFigure5.BothTDA7294areequippedwiththeirownprofessionalradiators.Whenvs=25V8,themaximumcontinuousoutputpowerreaches150W;when35V16,Themaximumcontinuousoutputpowerreaches170W.WeusedTDA7294standardapplicationcircuitandMarantzPM80andYAMAHAA-592tomakealisteningcomparison.Theformerisamid-pricedHi-FimachinewithaClassA,ClassAandBstatusswitch,andthelatterisa439.16dollarsclasswithAc-3inputAVpoweramplifier,audiosourceismusicfaxE60CD,speakerisTannerNo.5.ItturnsoutthatthesoundorientationofTDA7294hasadistinctiveEuropeanstyle,soft,mellow,delicate,andfullofbouncingfeeling.ItissimilartotheMarantzPM-80inClassAandBstatus,butthesoundfieldofPM-80isdeeperwhenworkinginpureClassA.ComparedwithYAMAHAA-592,thedifferenceislarger.ThelowfrequencyofA-592seemstobeslightlyimproved.Itsoundspowerful,butitisharderandthelinesareblurry.TDA7294issweetandnatural,withhigherresolution,reallylikelandscapepaintingdonewithsplashesofinkandfine-brushflowersandbirds(atechniqueofchineseink-painting),eachhasitsinfinitecharm.VI.ActiveSubwooferAmplifierAddsStandbyFunctionThiscircuitisanimprovementontheaudiocircuitusingtheintegratedcircuitTDA7294.ThecircuitdiagramisshowninFigure6.TDA729410pinhasamutefunction.WhentheexternalDCprovideshighlevel,theintegratedblockisintheworkingstate;whenthelowlevelisapplied,theintegratedblockisinthecut-offstate.Atthistime,thecircuitconsumeslittlepowerandIC114pinhasnooutput,thatis,standbyform.Thegeneralcircuitistoprovideahighleveltopin10tomakeitintheconductingstate,infact,thedevelopmentofthispinfunctioncanmeetsomespecialworkrequirements.Thiscircuitisbasedonthistoincreasethestandbyfunctionoftheactivesubwooferpoweramplifier,anditscircuitisreliableandresponsive.Figure6ActivesubwooferamplifieraddsstandbyfunctioncircuitdiagramVII.HighFidelityPowerAmplifierThecircuitisshowninFigure7.ThedrivestageadoptsTDA7294.Theinternaldrivestageandoutputstageofthechipusefieldeffecttubes,whicharepoweredby40V,andtheoutputpowercanreach70W(RL=8;THD=0.005%).Ithasadelicatetoneandanexcellentsenseofhearing.PoweroutputVT1,VT2adoptsShankenhigh-powerpairtube2SA1394,2SC3858.Thecircuitprincipleisasfollows:ThesignalisinputtotheTDA7294non-invertinginputpin③throughC1andR1.R7andR3,C3,C4ofICpin②formanegativefeedbacknetwork,theclosedloopgainofthisamplifierisabout34times.The⑨and⑩pinsarethestandbyandmuteterminalsrespectively.SincetheRCnetworktimeconstantofthe⑩pinislargerthanthatofthe⑨pin,theswitchingmachinesareallperformedundermutesatge,avoidingtheswitchingimpactsound,andC7isabootstrapcapacitor.Figure7High-fidelitypoweramplifierpromotedbyTDA7294Productionpoints:(1)InsulatingmicasheetsshouldbeaddedbetweenthemetalcapandtheheatsinkofTDA7294(themetalcapisconnectedtothepin⑧).(2)Thepowertransformerusesring-shaped300Wdouble20V,four50V/10000Ffiltercapacitors,two50V/100F,andtwo100V/0.1F.Thepowersupplypartshouldbetestedseparately,firstwithoutconnectingthepoweramplifier,measurewhetherthepositiveandnegativeoutputvoltageofthepowersupplyaresymmetrical,theerrorshouldbewithin0.6V.(3)Whentestingthemachine,forsafetyreasons,youshouldfirstusealowervoltagetest(suchas25V)withoutaddingasignal,andmeasuretheDCvoltageoftheoutputterminaltotheground.Normally,itshouldbewithin20mV.(4)R8,R9,R10,D1formthefinalbiascircuit.ThisbiasmakestheoutputtubesVT1andVT2notcutoffduringoperation,sothequiescentcurrentcanbesmall(about5mA).(5)Thepowertubeshouldbestrictlymatched(within3%)andgenuineproductsshouldbeselected.TheoutputresistanceR14isa5Wnon-inductivetype,andtheinductorLisformedbytightlywinding10turnsonR14withadiameterof1.5mmenameledwire.TDA7294uses60mmTimes,85mmTimes,20mm12-slotheatsink,andtheoutputpairtubeneedsaprofessionalheatsink.Thesectionswithhighcurrentontheprintedboardneedtobetin-rolled,whichisextremelybeneficialforthetransparencyandstrengthofthesound.Figure8PoweramplifierPCBpromotedbyTDA7294VIII.ClassABPowerAmplifierTDA7294integratedcircuitcanbeusedasahigh-fidelityaudioclassABpoweramplifier.Itcandrive4ohmor8ohmspeakers,andwhenconnectedtoan8ohmspeaker,itwillprovide50wattsofoutputpowerand0.1%THD.Figure9ClassABpoweramplifiercircuitdiagramYoumustinstallalargeenoughradiatorforTDA7294.Pin10isamuteinput,andpin9providesastandbymode.Muteshouldalwaysoccurwhenselectingstandbymode.TheIChasinternalthermalprotection,whichcausesmutereductionat145C,andtheamplifierentersstandbyat150C.TheTDA7294integratedcircuitheatsinkisinternallyconnectedtothenegativepowerrail.Ifthemoduleisinstalledinagroundedmetalenclosure,thentheICmustbeinsulatedfromtheheatsink.Ifnot,thenegativepowerrailwillbeshortedtoground.IX.Two-channelPowerAmplifierTDA7294high-powerintegratedcircuitICisspeciallydesignedforassemblinghigh-performanceaudioamplifiers.TwoTDA7294piecescanbeusedtomakeapowerfuldual-channelhigh-fidelitypoweramplifier.ThecircuitprincipleisshowninFigure10.TheoverallcircuitiscomposedoftwoTDA7294corecomponents,andtheperipheryincludessomeresistorsandcapacitors.Thecircuitsofthetwochannelsarealmostidenticalindesign.TheyallusethestandardcircuitofficiallyreleasedbyTDA7294,connectedtoanon-invertingamplifiercircuit,withavoltagegainof30.5dB,anoutputpowerofupto70Wperchannel,andadualpowersupplysymmetricalpowersupplyvoltage35V.Amongthem,Cl5andCl6areinputcouplingcapacitors.0.47Fisusedintheoriginalcircuit.Here,ifyouincreaseitto1F,youcanimprovethelow-frequencyresponseofthecircuit.Itisrecommendedtousepolypropylenespecialaudiocapacitors,suchasWIMAsMKT4seriescapacitors,itcangreatlyimprovethesoundresolution.R3andR4areinputresistances,whichdeterminetheinputimpedanceofTDA7294inthein-phaseamplificationstate.Here,22kisrelativelymoderate.Toolargeavaluecanreducetheburdenonthefront-endsignalsource,butitmayaffectthestabilityofTDA7294andmaketheoutputmidpointvoltagedriftincreased,toosmallvaluewillaffecttheresponseabilitytolowfrequency.ThetheoreticalvalueofthefeedbackresistorsR7andR8shouldbeequaltotheinputresistorsR3andR4,whichcanensurethebiascurrentbalanceoftheTDA7294inputdifferentialcircuitandreducesignaldistortion.ThefeedbackgroundresistanceR5,R6cooperateswithR7,R8tosetthecircuitgain.Here,thefeedbackDCblockingcapacitorsCl3andCl4areusedtoformACnegativefeedback,inhibitDCvoltageoutput,andprotectthespeaker.Figure10Two-channelpoweramplifiercircuitdiagramTDA7294hasastartmutefunction,andcooperateswithanexternalcircuittoachieveanon-impactsoundeffectwhenthepoweristurnedonandoff.R9,R1O,R11,Rl2,Cl7,Cl8andVD5,VD6intheschematicdiagramformanexternalmutecontrolcircuit.Delaytheenergizationofpins9and10ofTDA7294toachievethefunctionofsoftstart.Thepowersupplyrectifierfiltercircuitisalsoverysimple.Thefullbridgerectifiercircuitiscomposedof4EuropeanspeedrectifierdiodesVD1-VD4.CapacitorsC1andC2arethemainfiltercapacitors.Large-capacityandhigh-currentaudiofiltercapacitorsarerequired,suchasELNAsFORAUDIOseriesorBHCAerovoxindustrialgradecapacitors.DesignPCBisgenerallyabottleneckinamateurproduction,sothatmanyexcellentschematicdiagramshavenotbeentransformedintofinishedPCBsthatcanbeactuallyassembled.Here,thepopularProtel99sedesignsoftwareisusedtodrawtheprintedcircuitboardagainsttheschematicdiagram10,asshowninFigure11.The2mmthickFR-4board-baseddouble-sidedPCBisused,andthecopperfoilisthickenedto70mm,whichissuitableforhighcurrentpoweramplifiers.ThewholePCBtraceadoptsone-pointgroundingmethod,whicheffectivelyeliminatesgroundwireinterferencenoise.Insomehigh-currenttraces,tinplatingisalsoadoptedtoincreasetheadditionalcurrentcarryingcapacity.Thepowerinputandpoweroutputstructureuseshigh-currentscrewterminalstoensuresufficientover-currentcapabilityanddurabilityofrepeatedwiring.Figure11PrintedcircuitboardX.100WPowerAmplifierCircuitFigure12100WpoweramplifiercircuitdiagramcomposedofTDA7294Figure12isa100WpoweramplifiercomposedofamonolithicaudiopoweramplifierintegratedcircuitTDA7294.TDA7294includespre-opamplifier,finalpoweramplifier,temperatureprotection,shortcircuitprotection,mutecontrolandothercircuits.ThefinalstageadoptsbipolarDMOSpowertransistor,whichhasthecharacteristicsofhighoutputpower,bandwidth,lowdistortion,andgoodversatility.Theintegratedcircuitalsohasperfectanti-overload,anti-shortcircuitandtemperatureprotectioncircuitfunctions.Whenthechiptemperatureistoohigh,itautomaticallycutsofftheaudiosignaltoprotectthechipfromburningThepoweramplifiercircuitcomposedofTDA7294hasthecharacteristicsofsimpleperipheralcircuitandeasyproduction.Thecircuitinputimpedanceis20k,theinputsensitivityis750mV,thevoltagegainis32dB,thepowersupplyvoltagerangeis(25~40)V,andthequiescentcurrentis50mA.Whentheloadimpedanceis8,theoutputpoweris100W;whentheloadimpedanceis4,theoutputpowercanreach180W.Inactualproduction,TDA7294shouldbeequippedwithenoughheatsinks.Thesupportingpowercircuitshouldhavesufficientcapacity.Ifyouneedtoincreasethecircuitvoltagegain,youcanappropriatelychangetheratioofR3toR2,voltagegainA=201g(R3/R2)(dB).However,itisnotadvisabletoone-sidedlypursuethevoltagegainofthisstage.Excessivevoltagegaincaneasilycausecircuitself-excitation.Thesolutionistoincreasethevoltagegainofthepre-stage.

I.DescriptionTDA2030Aisoneofthehigh-fidelityintegratedpoweramplifiers,andmanypoweramplifiercircuitsusethisintegrationmethod.TDA2030isalsoaHI-FIpoweramplifierintegratedblockusedbymanycomputeractivespeakers.Ithassimpleconnectionmethodandaffordableprice.Theratedpoweris14W.Thepowersupplyvoltageis6~18V.Theoutputcurrentislarge,theharmonicdistortionandthecrossoverdistortionaresmall(14V/4ohm,THD=0.5%).Ithasexcellentshortcircuitandoverheatprotectioncircuit.Thefollowingdescribesitsconnectionandapplicationcircuit.CatalogI.DescriptionII.Connection2.1SinglePowerConnection2.2DualPowerConnectionIII.ApplicationCircuit3.1OTLFormPowerAmplifier3.2OCLFormPowerAmplifier3.3BTLFormPowerAmplifier3.440WPowerAmplifierCircuit3.5High-fidelityActiveSpeakerCircuit3.625WBridgeLowFrequencyPowerAmplifierCircuitOrdering&QuantityII.ConnectionItsconnectionmethodisdividedintosinglepowersupplyanddualpowersupply:2.1SinglePowerConnectionFigure1TDA2030singlepowerconnectiondiagram2.2DualPowerConnectionFigure2TDA2030dualpowerconnectiondiagramIII.ApplicationCircuit3.1OTLFormPowerAmplifierOTLformpoweramplifier:singlepowersupply,outputcouplingcapacitor.TheR5(150k)andR4(4.7k)resistorsinthecircuitshowninFigure3determinetheclosed-loopgainoftheamplifier.ThesmallertheR4resistor,thegreaterthegain,buttoolargegaincaneasilycausesignaldistortion.Twodiodesareconnectedbetweenthepowersupplyandtheoutputterminaltopreventtheinductiveloadofthespeakerfromkickingbackandaffectingthesoundquality.ThecapacitorofC3(0.22uF)andtheresistanceofR6(1)areusedtocompensatetheinductiveload(speaker)toeliminateself-excitation.Thecircuitusesa36Vsinglepowersupplyandtheoutputpowerisabout20W.Figure3OTLtypepoweramplifiermadewithTDA2030A3.2OCLFormPowerAmplifierTheformoftheOCLpoweramplifieradoptsdualpowersuppliesandhasnooutputcouplingcapacitor.AsshowninFigure4,sincethelowfrequencyresponseoftheoutputcouplingcapacitorisimproved,itisahigh-fidelitycircuit.Thedualpowersupplyusesatransformerwiththemiddlepointoftheprimarycoilgroundedandtheupperandlowervoltagesaresymmetricalandequal.Afterrectificationandfiltering,a18Vdualpowersupplyisformed,andtheoutputpoweris20W.Figure4OCLtypepoweramplifiermadewithTDA20303.3.BTLFormPowerAmplifierThemainfeatureofBTLis:itiscomposedoftwoidenticalpoweramplifiers,andtheinputsignalsareinversetoeachother.Thein-phaseinputandtheinvertedinputoftheamplifierareactuallyusedtoensurethattheinputsignalsareinversetoeachother.Atthesametime,theamplitudesofthetwoinputsignalsshouldbethesame,sothatthebasicrequirementsoftheBTLcircuitformcanbemet.ThecircuitdiagramisshowninFigure5,whereR7(1k)andR8(33)resistorsdividethesignalandtheattenuationfactorisexactlythesameastheamplificationfactorofU1.TheattenuatedsignalisaddedtotheinvertinginputterminalofU2throughR5.Infact,twoopampscompleteasignalamplification,andtheactualmeasuredoutputlevelis1.5timeshigherthanthatofanintegratedcircuit.Thatis,theoriginaloutputpoweroftheopampis20W,andtheoutputpowerisnowabout50W.However,duetothecharacteristicsoftheBTLcircuit,whenchoosinganintegratedcircuit,usetwooperationalamplifiercircuitswiththesameparametersasmuchaspossibletoadjusttheinputsignalamplitude.Youcanuseanoscilloscopetoobservetheamplitudeofthetwoinputsignalsbyinputtingasinewave.Atthistime,adjustR7tomakethetwoinputsignalsTheamplitudeisthesametoensurethatthenonlinearsymmetrydistortionisminimizedwhileincreasingthepower.Figure5BTLtypepoweramplifiermadewithTDA2030A3.440WPowerAmplifierCircuitFigure6isa40WpoweramplifiercircuitmadebyTDA2030poweramplifierintegratedblockandBD907/908:Figure640WpoweramplifiercircuitmadebyTDA20303.5High-fidelityActiveSpeakerCircuitAhigh-fidelityactivespeakercircuitdesignedwithTDA2030,thecircuitdiagramisshowninFigure7.Usingdualpowersupply,addedhighandlowbassandvolumeadjustment.WhendesigningthePCB,thegroundwireshouldnotpassthroughthecomponentpinsasmuchaspossibletoreduceDCnoise.Figure7Highfidelityactivespeakercircuitdiagram3.625WBridgeLowFrequencyPowerAmplifierCircuitFigure825WbridgelowfrequencypoweramplifiercircuitThecircuitinFigure8usestwoTDA2030sconnectedtoformabridgecircuit,withthesamecircuitstructureandparametersonbothsides.Theintegratedcircuitontherightiscontrolledbytheintegratedcircuitontheleftthrougha22knegativefeedbackresistor,andviceversa.Thediode1N4001isusedtopreventthespeakerinductiveloadfromgeneratingovervoltageanddamagingthedevice.Theamplificationfactorofthecircuitcanbeadjustedbychangingthenegativefeedbackvoltageratiobetweentheoutputterminal(pin4)andtheinvertinginputterminal(pin2).IDescriptionThisblogintroducesthepoweramplifierwithNE5532andLM1875Tasthecorecomponents.Thepoweramplifierwearediscussinghereisahigh-fidelitytwo-channelstereosubwooferpoweramplifier.Here,wewilldiscussitsmethodsandprocedures,schematicdesign,assemblyanddebugging,andspeakerproduction.Hopethisblogcanprovideagoodreferenceforbeginners.Figure1.LM1875CatalogIDescriptionIILM1875TandNE5532Overview2.1PowerAmplifierLM1875T2.2Pre-amplificationComponentNE5532IIICompositionofPowerSupplyIVAssemblyandDebuggingSpeaker4.1ElectricalInspection4.2BoxProductionVIntheEndOrdering&QuantityIILM1875TandNE5532OverviewFirst,weintroducethecorecomponentsthatwewilluse.Andthen,thebasiccharacteristicsofthesecomponents.Audiopoweramplifierisgenerallycomposedofthefollowingthreeparts:powersupply,pre-amplifierandpost-amplifier.Here,wewillusehigh-efficiencyHI-FIpowerintegratedchipLM1875Tasthecoreoriginal.LM1875Tadoptsapositiveandnegative15Vdualpowersupply,theleft,andrightchannelsworkinOCLmode,andthebassworksinBTLmode.AsfarasthecharacteristicsofLM1875Tareconcerned,ithasthecharacteristicsofgoodsoundquality,goodfrequencyresponse,lowcostandrelativelysimplecircuit.Inaddition,thepre-amplifierpartusestheNE5532integratedoperationalamplifier.2.1PowerAmplifierLM1875TLM1875Thasexcellentperformance.Manyluxury-lookingactivespeakers,mid-rangepoweramplifiers,andsubwoofersonthemarketuseLM1875T.ThepoweramplifiercircuitcomposedofLM1875Tchiphasthefollowingcharacteristics:Theoutputpowerislarge,themaximumpowercanreachabout20W;Thestaticcurrentissmall,theloadcapacityisstrong,andthedynamiccurrentislarge,whichcandrive4~8speakers;Thecircuitissimple,easytomanufactureandlowcost;Withaninternalprotectioncircuit,itisahigh-fidelitypoweramplifiercomponentwithstableperformance.Theblogdesignofthisarticleisadual-channelstereosubwooferpoweramplifier,butLM1875Tisamono-channelpoweramplifierintegratedcircuit,sothedual-channelOCLworkingmodeusesoneLM1875Tforeachchannel.SincethebassworksinBTLmode,wehavetousetwopieces.LM1875Thas5pins.Theyarepositivepowersupply,negativepowersupply,positiveinput,reverseinput,andoutput.ThecircuitisshowninFigure2.Figure2.LM1875Circuit2.2Pre-amplificationComponentNE5532Beforethepoweramplifiercircuit,itisgenerallynecessarytoaddapreamplifier.Thepurposeofthisistoamplifythevoltageofvariousinputweakelectricalsignals.Inordertoensurethattheoutputelectricalsignalhashighfidelity,thepre-amplifierisNE5532.NE5532isahigh-performance,low-noise,dualoperationalamplifierintegratedcircuit.Comparedwithmanystandardopamps,NE5532hasbettersoundperformance,excellentoutputdrivecapability,relativelyhighsmallsignalbandwidth,andlargepowersupplyvoltagerange.Therefore,itisverysuitableforhigh-qualityandprofessionalaudioequipment,instruments,controlcircuitsandtelephonechannelamplifiers.Whenusedforaudioamplification,thetoneiswarmandhighfidelity.ThefunctionalblockdiagramofNE5532isshownasinFig.3.Figure3.NE5532FunctionalBlockDiagramIIICompositionofPowerSupplyLM1875Tadoptsapositiveandnegative15Vdualpowersupply.TheoperatingvoltageofNE5532isalso15V.Weneedtostepdownthemainspowerto15Vthroughastep-downtransformer,thenrectifyitthroughtherectifierbridgeKBL406,filteritthroughalargecapacitor,anddirectlysupplyittothepoweramplifier.Inthisway,largeroutputpowerisobtained.After7815and7915,theregulatedoutput15VisusedasthepowersupplyofthepreamplifierNE5532.ThecompositionofthepowersupplyisshowninFigure4.Figure4.PowerCircuitFigure5.PowerAmplifierCircuitBoardIVAssemblyandDebuggingSpeakerWhenstartingthecircuitinstallation,firstcheckthecircuitboardagainstthecircuitdiagram.Forexample,checkwhetherthemaincomponentsareinstalledcorrectly,andwhetherthesolderjointshavemissingsolderingorfalsesoldering.Thenturnonthepowertodebugthecircuit,andmakespeakersafterthedebuggingiscompleted.TheactualproductionisshowninFigure6.Figure6.PhysicalShootingPic4.1ElectricalInspectionUseanACsignalgeneratortoaddatinysinusoidalsignaltothesignalinput.Then,usetheoscilloscopetomeasurethethreeoutputsignalsofthepoweramplifierboard.Atthistime,observewhetherthesinemeetstherequirementsandwhethertheparametersinthetestarerelativelystable.Then,connecttwofull-rangespeakerstotheleftandrightchannels,andconnectawoofertothebassoutputport.Atthistime,addthesongsignaltocarefullycheckwhetherthethreespeakersareworkingproperlyandthesoundisgood.Iftheabovestepsarewellexpressed,thenproceedtothenextstep.4.2BoxProductionThekeytomakingspeakersistheselection,sizeandothersteps.Intheexperiment,weusedthelaminatesinthelaboratoryforsplicingandassembly.First,drawasketch.Thepaintingisdividedonthreedifferentsubstrates,andthenmadeintotwopartsrespectively.Afterdrilling,polishing,splicingandbonding,thecompletedcircuitpartsareinstalledintheirrespectiveparts.Then,wedividetheentirepoweramplifierintothreeparts.Twosatellitespeakers,aswellasawooferandpoweramplifierboard.Thesethreepartstogetherformacomplete2.1subwooferpoweramplifier.Here,thereisaplacethatneedsspecialattention.Whenmakingthebasspartofthecabinet,theimpactofvibrationshouldbefullyconsidered.Therefore,wehavetodesigndampingcomponents.VIntheEndAftertheinstallationisnormal,connectthemusicsignalsourceandlistentothemusiceffect.Thesoundreproducedbythiscircuithasastrongsenseofhierarchy,aclearsenseoforientation,andanobvioussenseofspaceanddistance.Inaddition,thesoundimageorientationisclear,thewidthisoutstanding,andthesounddynamicrangeislarge,givingpeoplearealfeeling.