Tkool Electronics

Description74LS04containssixindependentgateseachofwhichperformsthelogicINVERTfunction.Theoutputsignalsofthesixinvertersareoppositetotheinputsignals.Theinvertercanreversethephaseoftheinputsignalby180degrees.Thiscircuitisusedinanalogcircuits,suchasaudioamplifier,clockoscillator,etc.Inverterisoftenusedinelectroniccircuitdesign.74LS04-HEXInverter-TruthTableExampleCatalogDescriptionCADModelsFeaturesApplicationPinoutCircuitDiagramPackageParametersElectricalCharacteristicsProductComplianceComponentDatasheetProductManufacturerFAQOrdering&QuantityCADModels74LS04FootprintFeaturesSupplyvoltagerange:+4.75Vto+5.25VMaximumsupplyvoltage:+7VMaximumcurrentallowedtodrawthrougheachgateoutput:8mATotallyleadfreeTTLoutputsMaximumRiseTime:15nsMaximumFallTime:15nsOperatingtemperature:0Cto70CApplication▪Indifferentlogiccircuit▪Indifferentservers▪Indifferentstoragemoduletostoredata▪Indifferentdigitalreluctancescircuitsandinstruments▪IndifferentnetworkingsystemsPinoutPinNumberDescriptionINPUTOFINVERTINGGATES11A-INPUTofGATE132A-INPUTofGATE253A-INPUTofGATE394A-INPUTofGATE4115A-INPUTofGATE5136A-INPUTofGATE6SHAREDTERMINALS7GND-Shouldbeconnectedtoground14VCC-ShouldbeconnectedtopositivevolatgeOUTPUTOFINVERTINGGATES21Y-OUTPUTofGATE142Y-OUTPUTofGATE263Y-OUTPUTofGATE384Y-OUTPUTofGATE4105Y-OUTPUTofGATE5126Y-OUTPUTofGATE6CircuitDiagramPackageParametersTechnologyFamilyLSVCC(Min)(V)4.75VCC(Max)(V)5.25Channels(#)6IOL(Max)(mA)8IOH(Max)(mA)-0.4ICC(Max)(uA)33InputtypeBipolarOutputtypePush-PullFeaturesHighspeed(tpd10-50ns),InputclampdiodeDatarate(Mbps)70ElectricalCharacteristicsProductComplianceECCNEAR99USHTS8542390001ComponentDatasheetDatasheet74LS04DatasheetProductManufacturerTexasInstrumentsInc.(TI)isanAmericantechnologycompanythatdesignsandmanufacturessemiconductorsandvariousintegratedcircuits,whichitsellstoelectronicsdesignersandmanufacturersglobally.ItsheadquartersareinDallas,Texas,UnitedStates.TIisoneofthetoptensemiconductorcompaniesworldwide,basedonsalesvolume.TexasInstrumentssfocusisondevelopinganalogchipsandembeddedprocessors,whichaccountsformorethan80%oftheirrevenue.TIalsoproducesTIdigitallightprocessing(DLP)technologyandeducationtechnologyproductsincludingcalculators,microcontrollersandmulti-coreprocessors.Todate,TIhasmorethan43,000patentsworldwide.FAQWhatis74LS04?74LS04isamemberof74XXYYICseries.The74-seriesaredigitallogicintegratedcircuits.74LS04IChassixNOTgates.TheseNOTgatesperformInvertingfunction.HencenameHEXINVERTINGGATES.Whatisthefunctionofic74ls04?74LS04HexNOTGateIC.74LS04isa2inputquadruple8-bitNOTgateIC.InverterinlogicconvertersisanelectronicsdevicewhosebasicfunctionsaretoinverttheincominglogicweatheritisHIGHorLOW.TheyarealsoknownasNOTgates.Whatisahexinverter?Ahexinverterisatypeofanintegratedcircuitthatcontainssixinverters.Manysophisticateddigitaldevicesuseinverters,includingmultiplexers,decoders,andstatemachines.Aninvertercircuitsmainfunctionistooutputthevoltagerepresentingtheoppositeleveltoitsinput.WhyisNOTgatecalledaninverter?ANOTgate,oftencalledaninverter,isanicedigitallogicgatetostartwithbecauseithasonlyasingleinputwithsimplebehavior.ANOTgateperformslogicalnegationonitsinput.Inotherwords,iftheinputistrue,thentheoutputwillbefalse.Whatarethe7basiclogicgates?Therearesevenbasiclogicgates:AND,OR,XOR,NOT,NAND,NOR,andXNOR.TheANDgateissonamedbecause,if0iscalledfalseand1iscalledtrue,thegateactsinthesamewayasthelogicalandoperator.ThefollowingillustrationandtableshowthecircuitsymbolandlogiccombinationsforanANDgate.

RI901

Description74LS04containssixindependentgateseachofwhichperformsthelogicINVERTfunction.Theoutputsignalsofthesixinvertersareoppositetotheinputsignals.Theinvertercanreversethephaseoftheinputsignalby180degrees.Thiscircuitisusedinanalogcircuits,suchasaudioamplifier,clockoscillator,etc.Inverterisoftenusedinelectroniccircuitdesign.74LS04-HEXInverter-TruthTableExampleCatalogDescriptionCADModelsFeaturesApplicationPinoutCircuitDiagramPackageParametersElectricalCharacteristicsProductComplianceComponentDatasheetProductManufacturerFAQOrdering&QuantityCADModels74LS04FootprintFeaturesSupplyvoltagerange:+4.75Vto+5.25VMaximumsupplyvoltage:+7VMaximumcurrentallowedtodrawthrougheachgateoutput:8mATotallyleadfreeTTLoutputsMaximumRiseTime:15nsMaximumFallTime:15nsOperatingtemperature:0Cto70CApplication▪Indifferentlogiccircuit▪Indifferentservers▪Indifferentstoragemoduletostoredata▪Indifferentdigitalreluctancescircuitsandinstruments▪IndifferentnetworkingsystemsPinoutPinNumberDescriptionINPUTOFINVERTINGGATES11A-INPUTofGATE132A-INPUTofGATE253A-INPUTofGATE394A-INPUTofGATE4115A-INPUTofGATE5136A-INPUTofGATE6SHAREDTERMINALS7GND-Shouldbeconnectedtoground14VCC-ShouldbeconnectedtopositivevolatgeOUTPUTOFINVERTINGGATES21Y-OUTPUTofGATE142Y-OUTPUTofGATE263Y-OUTPUTofGATE384Y-OUTPUTofGATE4105Y-OUTPUTofGATE5126Y-OUTPUTofGATE6CircuitDiagramPackageParametersTechnologyFamilyLSVCC(Min)(V)4.75VCC(Max)(V)5.25Channels(#)6IOL(Max)(mA)8IOH(Max)(mA)-0.4ICC(Max)(uA)33InputtypeBipolarOutputtypePush-PullFeaturesHighspeed(tpd10-50ns),InputclampdiodeDatarate(Mbps)70ElectricalCharacteristicsProductComplianceECCNEAR99USHTS8542390001ComponentDatasheetDatasheet74LS04DatasheetProductManufacturerTexasInstrumentsInc.(TI)isanAmericantechnologycompanythatdesignsandmanufacturessemiconductorsandvariousintegratedcircuits,whichitsellstoelectronicsdesignersandmanufacturersglobally.ItsheadquartersareinDallas,Texas,UnitedStates.TIisoneofthetoptensemiconductorcompaniesworldwide,basedonsalesvolume.TexasInstrumentssfocusisondevelopinganalogchipsandembeddedprocessors,whichaccountsformorethan80%oftheirrevenue.TIalsoproducesTIdigitallightprocessing(DLP)technologyandeducationtechnologyproductsincludingcalculators,microcontrollersandmulti-coreprocessors.Todate,TIhasmorethan43,000patentsworldwide.FAQWhatis74LS04?74LS04isamemberof74XXYYICseries.The74-seriesaredigitallogicintegratedcircuits.74LS04IChassixNOTgates.TheseNOTgatesperformInvertingfunction.HencenameHEXINVERTINGGATES.Whatisthefunctionofic74ls04?74LS04HexNOTGateIC.74LS04isa2inputquadruple8-bitNOTgateIC.InverterinlogicconvertersisanelectronicsdevicewhosebasicfunctionsaretoinverttheincominglogicweatheritisHIGHorLOW.TheyarealsoknownasNOTgates.Whatisahexinverter?Ahexinverterisatypeofanintegratedcircuitthatcontainssixinverters.Manysophisticateddigitaldevicesuseinverters,includingmultiplexers,decoders,andstatemachines.Aninvertercircuitsmainfunctionistooutputthevoltagerepresentingtheoppositeleveltoitsinput.WhyisNOTgatecalledaninverter?ANOTgate,oftencalledaninverter,isanicedigitallogicgatetostartwithbecauseithasonlyasingleinputwithsimplebehavior.ANOTgateperformslogicalnegationonitsinput.Inotherwords,iftheinputistrue,thentheoutputwillbefalse.Whatarethe7basiclogicgates?Therearesevenbasiclogicgates:AND,OR,XOR,NOT,NAND,NOR,andXNOR.TheANDgateissonamedbecause,if0iscalledfalseand1iscalledtrue,thegateactsinthesamewayasthelogicalandoperator.ThefollowingillustrationandtableshowthecircuitsymbolandlogiccombinationsforanANDgate.

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.

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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.IntroductionLM3886isahigh-performanceaudiopoweramplifier.ItexhibitsextremelylowTHD+Nvaluesof0.03%attheratedoutputintotheratedloadovertheaudiospectrum,andprovidesexcellentlinearitywithanIMD(SMPTE)typicalratingof0.004%.Itisverysuitablefortheenthusiastswhopursuebothbeautifulsoundqualityandstrongvolume.ThisarticleintroducesseveralpracticalapplicationsofLM3886inhometheatersystems.ThisisatechnicalexaminationvediooftheLM3886Amplifier.CatalogIntroductionCatalogIHighQualityDual-channelPowerAmplifierIIPowerfulBTLPowerAmplifierIIISubwooferSpeakerOrdering&QuantityIHighQualityDualChannelPowerAmplifierLM3886outputsnearly70Wpoweratratedvoltageandthepeakpoweris150W.Thedualchannelpoweramplifieradoptssimpleandtypicalcircuit,whichcanreplaceavarietyofHI-FIpoweramplifier,andissuitablefortheleftandrightmainchannelofpoweramplifierinhomecinema.ThewholecircuitisinstalledonthesamePCB.EachofthetwoLM3886sisequippedwithaspecialaluminumradiator(length140,thickness50,height75(mm)),whicharefixedonbothsidesofthePCBtofacilitateheatdissipation.Thepowertransformercanchoosedouble24~28V,3~5A.IIPowerfulBTLPowerAmplifierApureBTLbridgeamplifieriscomposedofanoperationalamplifierNE5532,anLM3886in-phaseamplifierandanLM3886invertingamplifier,whichcaneasilyoutputmorethan200Wundistortedpower.Itcanbeusedindancehalls,karaoke,theatersandotheroccasions.Thiscircuitcankeepthesoundqualitynaturalandsmoothwhenplayingatlowvolume.BTLPoweramplifiercircuitisshowninFigure1.Onecircuitboardforeachchannel,withindependentrectification.Thesizeoftworadiatorsis140mminlength,50mminthicknessand100mminheight.Figure1.BTLPowerAmplifierCircuitIIISubwooferSpeakerFigure2isthecircuitofahouseholdsubwooferspeaker.Figure2.circuitofsubwooferspeakerInthepicture,theLinkwitzactivecompensatoraccuratelycontrolsthecenterfrequencyf1ofthecompensationpeakanditsQvalue,sothattheclosedbox(seeFigure3)withanaturalcornerfrequencyabout50Hzandthefrequencyresponsecurve(seeFigure4)extendsdownflatly.Thelowend-3dBpointreaches25Hz.Figure3.ClosedboxFigure4.frequencyresponsecurveInFigure4,curveAisnaturalfrequencyresponse;Biscompensationcurve;andCissystemfrequencyresponse.Theturningfrequencyofthelow-passfilteriscontinuouslyadjustablefrom80Hzto200Hz,sothattheactivesubwoofercanmatchthereadersdualchannelspeakerwithdifferentfrequencylimits.TheloudspeakerusessilverfluteYD310-43.Thebasindiameteris310mm.Themagnetdiameteris158mm.Theresonancefrequencyis25Hz.Q=0.35.Thecontinuouspoweris50W,andthesensitivityisashighas95dB.ComparedwiththeHiviS8unitwithasensitivityof88dB,thesensitivitydifferencebetweenthetwois7dB.Fortheclosedbox,theoutputsoundpressureofYindiYD310-43whenitinput50WisequivalenttotheoutputofHiviS8unitwhenitinput200W.YindicanalsobereplacedbytheBlueWhaleYD310-8XA.Insteadofthebassreflexwithpoortransientperformanceandlowsensitivity,itisbettertousethesimplestclosedbox.Theboxshallbesolidandairtight,filledwithglassfibercottonoracryliccottonforwarmthabsorption,andthesmallcavityatthebottomoftheboxshallbeusedtoinstallthecircuitpart.Forthesakeofsimpleinstallation,allcircuitsareinstalledonthePCB.ThePCB,radiator,switchandI/Oconnectorarefixedonthemetalpanel,andthenfixedonthespeakerwith6screws.Then,itcanworkafterconnectingtohornandtransformer.Connectthesubwooferactivespeakerwiththehomestereospeakertoforma3Dplaybacksystem.

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ⅠIntroductionAlinefollowingcardesignedwithLM393VoltageComparatorcapableoftrackingonaspecificrunway.Thelinefollowingcarmainlyincludesasolarpowersupplypartandatrackingcontrolpart.Thecontrolcircuitpartmainlyincludesabattery,aswitch,firstandsecondlightsensitivecircuits,aDCmotor,acomparisoncircuit,andamotordrivecircuit.ThisblogtestshowsthatthelinefollowingcarcontrolledbytheLM393voltagecomparatorhasthecharacteristicsofhighcontrolaccuracy,faststartandstop,etc.,andsolvestheproblemsofthecomplicatedcontrolcircuitstructureofthelinefollowingcarandthelargedeviationofthedrivingtrajectory.CatalogⅠIntroductionⅡWhatisLM393?ⅢWhatisALineFollowingCar?3.1SolarPowerDesign3.2LineFollowingDesignⅣCircuitDesignofLineFollowingCarⅤTestⅥConclusionOrdering&QuantityⅡWhatisLM393 ?TheLM393offersexceptionalvalueforcost-sensitiveapplicationswithaloweroffsetvoltage,highersupplyvoltagecapability,lowersupplycurrent,lowerinputbiascurrent,shorterpropagationdelay,aswellasimproved2kVESDperformanceandinputrobustnesswithdedicatedESDclamps.TheLM393devicesconsistoftwoindependentvoltagecomparatorsthataredesignedtooperatefromasinglepowersupplyoverawiderangeofvoltages.Thequiescentcurrentisindependentofthesupplyvoltage,andtheoutputscanbeconnectedtootheropen-collectoroutputstoachieveawiredANDrelationship.Figure1.LM393ⅢWhatisALineFollowingCar?Alinefollowingcarisacarthatcantravelalongapresettrajectory.Intheprocessofdrivingthelinefollowing,howtomakethecarcanaccuratelyfollowthetrajectorywithoutlargedeviationsisthefundamentalapplicationofthelinefollowingcar.However,theexistinglinefollowingcargenerallyusestheinfraredreflectionmethodtofeedbackthedrivingtrajectoryofthecar,thecontrolcircuitstructureismorecomplicated,andtheinfraredreflectioniseasilyaffected,sonotonlythecostishigher,butalsothedrivingtrajectoryofthecarispronetodeviation,soitoftendoesnotmatchthedesigntrajectory.UsingLM393voltagecomparatorasthemaincontrolchipofthetrackingcarwillbeabetterway.UsetheresistancechangeofthephotoresistorunderthelightintensityandtheLM393voltagecomparatortocontroltheleftandrightdrivingwheelsofthecartorealizethetrackingdriveofthecar,andcooperatewiththedisplaycircuittounderstandthestatusofthecar.TheprincipleblockdiagramoflinefollowingcarbasedonLM393voltagecomparatorisshowninFigure3.Figure2.LineFollowingCarⅣCircuitDesignofLineFollowingCarThecircuitdesignoflinefollowingcarbasedonLM393voltagecomparatormainlyincludessolarpowersupplyandcartrackingdesign.Themaincomponentsofthelinefollowingcarincludeabatterybox,acontrolcircuitboardattachedtothebottomofthebatteryboxbydouble-sidedadhesive,andseveralwheelassembliesinstalledonbothsidesofthecontrolcircuitboardandasolarbatterypanelinstalledabovethebatterybox.Figure3.BlockDiagramofLineFollowingCar3.1SolarPowerDesignThelinefollowingcaradoptsbatterypowersupplyandstorage.Thesolarbatteryboardprovidespowerforthebattery,thatis,thebatteryinthecarischargedfirst,andonlywhenthebatteryhasenoughpoweroutputvoltage,therequiredvoltagecanbeoutputattheoutputendofthebatterytodrivethetracingcar.ThedesignofthepowersupplypartmentionedinthisblogusesasinglelithiumbatterychargingmanagementchipTP4057withaninputvoltageof4V9V(typicalvalue5V),whichcanbeusedtochangetheresistancetocontrolthechargingcurrent,anditsadjustmentrangeis100mm500mAandthecut-offvoltageis4.2V.Thechargingcircuithassimpleperipherals,noexternalswitchtubeisrequired,andhasfunctionssuchaschargingindicationandfullindication,anti-reversebatterypositiveandnegativepolereverseconnectionprotection,andpowersupplyundervoltageprotection.Inadditiontousingsolarpanelstopowerthecircuit,itcanalsoworkwithUSBpowerandadapterpower.Figure4.SchematicDiagramofChargingCircuit3.2LineFollowingDesignThecartrackingadoptstheLM393voltagecomparatorasthecontrolcenteroftheentiretrackingcircuit.LM393isadualvoltagecomparatorintegratedcircuit,whichiscomposedoftwoindependentprecisionvoltagecomparators.Itsfunctionistocomparetwoinputvoltagesandchangetheleveloftheoutputvoltageaccordingtothelevelofthetwoinputvoltages.TheschematicdiagramusingtheLM393voltagecomparatorasthetrackingcontrolcircuitisshowninFigure5.ThiscarchoosesredLEDlightasitslightsource.Whenthelightsourceshinesonwhiteobjectsandblackobjects(thepredeterminedtrajectoryofthecarisblack),thereflectivityisdifferent.Thelightisreflectedontothephotoresistorthroughtheground.WhentheredLEDlightisprojectedonthewhiteareaandtheblacktrackline,theresistanceofthephotoresistorwillbesignificantlydifferentbecauseofthedifferentreflectance;Bydetectingtheresistancechangeofthephotoresistor,itcanbejudgedwhetherthecarisdrivingontheblacktrackline.ThiscarchoosesredLEDlightasitslightsource.Whenthelightsourceshinesonwhiteobjectsandblackobjects(thepredeterminedtrajectoryofthecarisblack),thereflectivityisdifferent.Thelightisreflectedontothephotoresistorthroughtheground.WhentheredLEDlightisprojectedonthewhiteareaandtheblacktrackline,theresistanceofthephotoresistorwillbesignificantlydifferentbecauseofthedifferentreflectance;Bydetectingtheresistancechangeofthephotoresistor,itcanbejudgedwhetherthecarisdrivingontheblacktrackline.Figure5.SchematicDiagramofTracingIftheresistanceofthephotoresistorchanges,itmeansthatthewhiteareahasbeendetected,andthecarhasdeviated;atthistime,themotoroftheleftorrightwheelofthecarisdeceleratedorevenstoppedtomakethecarreturntotheblacktrack.ThetrackcarrunsonasimilarS-shapedroutetoachievethelinefollowingfunction.Whenthereisanimbalance(forexample,onewheelispressedontheblacktrackline),themotorononesideisstoppedimmediately,andthemotorontheothersideisacceleratedtorotate,sothatthecarcancorrectthedirectionandreturntothecorrectdirection.Thewholeprocessisaclosedloopcontrol,soyoucanquicklyandsensitivelycontrolthemovementofthelinefollowingcar.Atthesametime,thephotoresistorcandetecttheintensityoftheexternallight.Thestrongertheexternallightis,thesmallertheresistancevalueofthephotoresistoris.TheleftandrightwheeldriveofthistrackingcarusesaDCmotorwithareductiongear.TheDCmotordrivesthecartoslowdown,otherwisethecarwillruntoofastifthespeedistoohigh.Moreover,thetorqueistoosmalltorunevenwithoutdeceleration.Themotorusedinthislinefollowingcarhasintegratedareductiongeartogreatlyreducethedifficultyofproductionanddebugging.Comparedwiththeuseofasingle-chipmicrocomputerasthecontrolcircuit,thecontrolcircuitcomposedoftheLM393voltagecomparatorhasasimplerstructure,isconvenientforassemblyanddebugging,andhasalowercost.ⅤTestFirstofall,placethecaronthewhitebackgroundtestfieldoftheblacktrackline(theblackrunwayisthecarspresettrack),andturnontheswitchesS1,S2,solarpanels(orbatteries)toprovideelectricity,sothatthevoltagecomparatorcontrolsthestartoftwoDCmotorstodrivethewheelassembliesonbothsidesofthecar.OurDIYlinefollowingcarbegantodrivealongthedesignedtrack(blackrunway)!Duringthedrivingofthecar,thelight-emittingdiodesD2andD3ontheleftandrightsidesofthecarbothemitredlightsources.Becausethelightsourceirradiatestheblackrunwayandthewhiterunwaywithdifferentreflectivity,andthephotoresistorcandetecttheexternallightintensity,thestrongertheexternallight,thesmallerthephotoresistorresistance,theweakertheexternallight,thegreatertheresistance.Therefore,whentheredLEDlightisprojectedontotheblackandwhiterunway,becauseofthedifferentreflectance,theresistanceofthephotoresistorwillbesignificantlydifferent.Figure6.RedLEDWhenthelightsourceisreflectedbytherunwaytothephotoresistorsR14andR15,thecomparatorcandeterminewhetherthecarisdrivingontheblacktracklineorthewhiteareaaccordingtothechangesintheresistanceofthephotoresistorsonbothsides.Andthroughthediodesandphotoresistorsontheleftandrightsides,wecanalsodeterminewhichsidethecarisdeflectingatthistime.Whenanimbalanceoccurs(forexample,thesideofthecarispressedagainstthewhitearea),theDCmotorononesideisimmediatelystopped,andtheDCmotorontheothersideisacceleratedtorotate,sothatthecarcancorrectthedrivingdirectionandreturntothecorrectdrivingdirection(blacktrackon-line.Actually,wecanseethattheleftandrightdrivingwheelsofthecarrotateinturnandstopdrivingthecarforward;thereisaprocessofdeviation,correction,deviation,andcorrection;butitalwaysadvancesalongtheestablishedblacktrajectory.ⅥConclusionThesolartrackingcardiscussedinthisblog:Passedthetestandsuccessfullyrealizedthecarslinefollowing;Canbepoweredbysolarenergyorbattery;Strongstabilityandanti-interferenceability,highcontrolaccuracy,faststartandstop;Solvedtheproblemsofcomplicatedcontrolcircuitoflinefollowingcarandlargedeviationofdrivingtrajectory.UsingonlytheLM393voltagecomparatorasthecontrollercircuitallowsustoassembleanddebugconvenientlyandatalowercost.Theuseofnon-singlechipcontrolisafeatureofthislinefollowingcar.Figure7.LM393Insummary,thelinefollowingcarbasedonLM393controlissuitablefortechnologicalinnovationandtechnologypromotion.Afterreadingtheblog,haveyoubetterunderstandLM393?Finally,ifyouhaveanyquestionsaboutLM393,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!IDescriptionLM1875isapoweramplifierintegratedblockchip.Itssuperiorperformanceandattractivetonehavebeenacceptedbymanyenthusiasts,anditwasalltherageinthe1990s.LM1875adoptsTO-220packagestructure,whichisshapedlikeamid-powertube,smallinsize,simpleinperipheralcircuits,andlargeinoutputpower.Theintegratedcircuitintroducedinthisblogisequippedwithoverload,overheatingandinductiveloadreversepotentialsafetyprotection,whichisoneoftheidealchoicesforhigh-endaudio.Figure1.LM1875CatalogIDescriptionIILM1875ParametersIIILM1875CircuitPrincipleIVLM1875CircuitAssemblyandDebuggingVIntheEndOrdering&QuantityIILM1875ParametersVoltageRange16~60VQuiescentCurrent50MmAOutputPower25WHarmonicDistortion0.02%,whenf=1kHz,RL=8,P0=20WRatedGain26dB,whenf=1kHzWorkingVoltage25VConversionRate18V/SIIILM1875CircuitPrincipleThiscircuitiscomposedofanattenuatedtonecontrolcircuitcontrolledseparatelyforhighandlowsounds,LM1875amplifiercircuitandpowersupplycircuit.Amongthem,thesoundqualitycontrolpartusesanattenuatedtonecircuitcontrolledseparatelyforhighandlowsounds.Thespecificcomponentsareasfollows:R02,R03,C02,C01,W02formabasscontrolcircuit;C03,C04,W03formatreblecontrolcircuit;R04istheisolationresistance;W01isthevolumecontroller,whichadjuststhevolumeoftheamplifier;C05isanisolationcapacitortopreventthedownstreamLM1875DCpotentialelementfromaffectingtheprevioustonecircuit.TheamplifyingcircuitmainlyadoptsLM1875,whichiscomposedof1875,R08,R09,C066,etc.ThemagnificationofthecircuitisdeterminedbytheratioofR08toR09;C06isusedtostabilizethedriftoftheLM1875s4thpinDCzeropotential,butithasacertainimpactonthesoundquality;C07andR10functiontopreventtheamplifierfromgeneratinglow-frequencyself-excitation.InAddtion,theloadimpedanceofthisamplifieris416.Figure2.LM1875CircuitWhataboutthepowersupplycircuitofthepoweramplifier?Pleasetakealookatthepicturebelow.Inordertoensurethesoundqualityofthepoweramplifierboard,weneedtopayattentiontothefollowingwhendesigningthecircuit:Theoutputpowerofthepowertransformershallnotbelessthan80W;Theoutputvoltageis2*25V;Thefiltercapacitorusestwo4700UF/25Velectrolyticcapacitorsinparallel;Positiveandnegativepowersuppliesshare44700UF/25Vcapacitors;Thetwo104basecapacitorsarehigh-frequencyfiltercapacitors;Onlyiftheaboverequirementsaremet,theamplifiercanmaintainbettersoundquality.Figure3.LM1875CircuitIVLM1875CircuitAssemblyandDebuggingThisblogwillintroducethenecessarytoolsforcircuitassembly,howtoprepareforsoldering,andfinallyhowtodebugthecircuit.Ofcourse,ifyoustillfeellikeyouarestillcannotgetenough,intheendyoucanevenfollowourtipstotryanextrainterestingexperimentwiththiscircuit.ToolsThatYouNeedA20Welectricsolderingiron,preferablywithadjustabletemperature;Amultimeter;Apairofneedlenosepliers;Ascrewdriver;Somesolderwireandpineperfume.HowtoPrepareforWeldingWeldingsequence:①Weldingjumpers;②Weldingresistance;③Weldingcapacitor;④Weldedrectifiertube;⑤Weldingpotentiometer;⑥WeldLM1875.NotesFixtheLM1875withscrewsontheheatsinkbeforeweldingLM1875,otherwisethescrewswillbedifficulttodriveinwhentheheatsinkisinstalledattheend;ThepartofLM1875incontactwiththeheatsinkmustbecoatedwithasmallamountofheatdissipationgreasetofacilitateheatdissipation;Payattentiontotheweldingqualitywhenwelding.Forbeginners,youcanpracticeafewmoretimesontheoldcircuitboard,andthenformallysolder.HowtoDebugCorrectlyThedebuggingofthispoweramplifierboardisverysimple.Afterthecircuitboardissolderedwithelectroniccomponents,wemustcarefullycheckthecircuitboardforsolderingerrors.Specialattentionshouldbepaidtoelectronicpartswithpolarity,suchaselectrolyticcapacitorsandbridgerectifiers.Oncetheweldingisreversed,thereisariskofburningthecomponents.Whenthetransformerisconnected,theoutputterminaloftheamplifierisnotconnectedtothespeaker,butconnectedtoamultimeter(preferablydigitaldisplay,andthemultimeterissettoDC*2V).Inaddition,payattentiontothereadingofthemultimeterwhenpoweringonthepoweramplifierboard.Undernormalcircumstances,thereadingshouldbewithin30mV,otherwiseweshouldimmediatelycutoffthepowertocheckthecircuitboard.Ifthereadingoftheelectricmeteriswithinthenormalrange,itindicatesthatthefunctionofthepoweramplifierboardisbasicallynormal.Atthistime,weconnectedthespeaker,theninputthemusicsignal,andthenpoweronthetestmachine.Underthecorrectproceduresandspecifications,turnthevolumepotentiometer,thevolumeshouldchange,andturnthehighandlowknobs,thetoneofthespeakerwillchange.Figure4.LM1875ExperimentWorthTryingFirst,wewillshort-circuitC6andmeasuretheDCpotentialattheoutputofLM1875withamultimetertoseeifitiswithin30MV.Then,connectthespeakerandtestfortwohours.UseamultimetertomeasuretheDCpotentialattheoutputoftheLM1875toseeiftheDCpotentialiswithin30MV.IftheDCpotentialiswithin30MV,thecapacitorC6canbeomitted.Inthiscase,theamplifierboardbecomesapureDCpoweramplifier.VIntheEndSofar,thepoweramplifierboardhasbeensuccessfullyinstalledandadjusted.Lookingatthispieceofworkthatyoucanbeproudofandenjoyingthewonderfulmusic,areyousatisfied?

RI901

IDescriptionThisblogintroducesthedesignofalithiumbatterybackuppowercontrolboardbasedonLM393,whichissimple,stable,reliable,andlow-cost.Itcandirectlyoutputthemainsvoltagewhenthereismainspower,andcontinuouslymonitorthemainsvoltage.Notonlycanthisdesignautomaticallyturnontheinverterwithin10msafterthemainspowerisoff,butitalsohasapowermanagementfunction:whentheinternallithiumbatteryvoltageislowerthanthesetvalue,itwillautomaticallycharge.ThisVediointroducesHowDoesLM393WorksCatalogIDescriptionIIDesignandWorkingPrinciple2.1Design2.2WorkingPrincipleIIITestIVConclsionOrdering&QuantityIIDesignandWorkingPrincipleThedetailsofLM393basedlithiumbatterybackupcircuitareasfollows:2.1Design2.1.1MainsPowerFailureWhenthereisnomainspowerinput,thecontrolpanelwillturnontheinverterandoutput220VACwithin10msofthemainspowerfailure.2.1.2ChargingManagementFigure1.FunctionDiagramWhenthereismainsinput,thecontrolboardfirstshutsdowntheinverteroutputandswitchestothemainsoutput;thenentersthechargingmanagementstate(duetothefeatureofthelithiumbatteryprotectionboard,theprotectionboardstopschargingafteroverchargeprotection.WhenthebatteryvoltageWhenitdropstotheoverchargerecoveryvalueorbelow,itwillautomaticallyresumecharging.Whenthereismainsinputforalongtime,thelithiumbatterychargerwillberepeatedlycharged,whichwillaffectthelifeofthelithiumbattery).Whenthelithiumbatteryisfullycharged,itwillstopcharging.Whenitdropstoacertainlevel(thisparameterislowerthantheoverchargerecoveryvalueofthelithiumbatteryprotectionboard,thespecificparametervalueisadjustable)andthenresumecharginguntilitisfullycharged,andrepeattheaboveprocess.2.2WorkingPrincipleAccordingtothedesignrequirements,theprincipledesignofthiscontrolboardisdividedintotwoparts:lithiumbatteryvoltagedetectionandcontrol,andmainsvoltagedetectionandcontrol.ThemainvoltagecomparisonpartofthecontrolboardusesthedualvoltagecomparatorintegratedchipLM393.LM393integrates2independentcomparators,itsoperatingpowersupplyvoltagerangeiswide,itcanworkfor2~36Vwhensinglepowerinput,and1~18Vwhendualpowerinput.Inaddition,itscurrentconsumptionissmall,only0.8mA.AndwhatisthepinoutofLM393?WecantakealookatFigure2below:Pins3,5arethenon-invertinginputterminalsofthetwocomparatorsrespectively;Pins2,6aretheinvertinginputterminalsofthetwocomparatorsrespectively;Pins1,7arethecorrespondingoutputterminalsofthetwocomparatorsrespectively.Figure2.LM393PinoutWhenusedasabasiccomparisoncircuit,ifthevoltageatthenon-invertinginputterminalisgreaterthanthevoltageattheinvertinginputterminal,thecorrespondingoutputterminaloutputsahighlevel,andviceversa.Forexample,whenU5U6,U7outputshighlevel;whenU5U6,U7outputslowlevel.2.2.1LithiumBatteryVoltageDetectionandControlLithiumbatteryvoltagedetectioncontrolisshowninFigure3.(1)PowerSupplyThepowersupplyofthecontrolpartistakenfromthelithiumbatteryofthebackuppowersupply,andthevoltageofthecontrolboardis12VDC.Becausethelithiumbatteryinthisdesignis48V,itsvoltagerangeis32Vto54.6V,whichishigherthanthelargeinputvoltagerequiredbythestabilizerblock7812.Therefore,inordertoprotectthevoltageregulatorblock7812,weneedtoconnecta20Vvoltageregulatortubeinseriesattheinputtostepdown.Here,diodeD5actsasreversevoltageprotection(2)VoltageComparisonThepowermanagementadoptsthecomparatorLM393,thesamplingvoltageofthelithiumbatteryisdividedbyresistorsR11andR12,andtheninputtothenon-invertinginputofLM393.Thereferencevoltagedivides12VthroughtheresistorR4andthepotentiometer,andthenenterstheinvertinginputofLM393.WhenthesamplingvoltageU1ishigherthanthereferencevoltageU2,theoutputterminalcorrespondingtoLM393outputsahighlevel,thetransistor9012isturnedoff,therelaydoesnotoperate,andtheinverterstopsworking.WhenthesamplingvoltageU1islowerthanthereferencevoltageU2,theoutputterminalcorrespondingtoLM393outputsalowlevel,thetransistor9012isturnedon,therelayacts,andtheinverteristurnedon.ThereferencevoltagecanbeadjustedaccordingtotheactualparametersthroughthepotentiometerR5.Figure3.LM393LithiumBatteryVoltageDetectionandControl(3)HysteresisComparatorCircuitInasingle-limitcomparator,iftheinputsignalUinhasaslightinterferencenearthethreshold,theoutputvoltagewillproducecorrespondingjitter(fluctuation).Forexample,inthedesignoflithiumbatteryvoltagedetection,ifthesamplingvoltageofthelithiumbatteryfluctuatesnearthetargetvoltage(seeFigure3),thevoltageofU1ishigherthanthevoltageofU2,andtheoutputofthecomparatorshouldoutputahighlevel.However,iftheU1voltageorU2voltagefluctuatesslightlyatthistime,thetransistor9012islikelytobeturnedonandofffrequentlyatthistime,andthecontroloutputwillbeveryunstable.Thenhowtoovercomethisshortcoming?Wecanintroducepositivefeedbackinthedesign(thatis,thewayofhardwaretoachievereturndifference).Ifweneedtofixatrippointatacertainreferencevoltagevalue,wecaninsertanon-linearelement(suchasacrystaldiode)inthepositivefeedbackcircuit.Byusingtheunidirectionalconductivityofthediode(inFigure2,D10diode1N4148),theaboverequirementscanbeachieved.2.2.2MainsVoltageDetectionandControlThedescriptionofthemainsvoltagedetectioncontrolpartisshowninFigure4.(1)PowerSupplyPartThepowersupplypartusesthesamepowersupplyDC12Vasthelithiumbatteryvoltagedetectionandcontrolpart.(2)MainsVoltageDetectionTakingintoaccountthecostofthemainsvoltagedetectionpart,thisdesignabandonsthetraditionaltransformerorvoltagetransformerdetectionmethod,andusestwooptocouplerchipsPC817todetectthemains.PC817isacommonlyusedlinearoptocoupler,whichisoftenusedinfunctionalcircuitsthatrequiremoreprecision.Whenanelectricalsignalisappliedtotheinputend,thelightemitteremitslightandilluminatesthelightreceiver.Thelightreceiveristurnedonafterreceivingthelight,andgeneratesaphotocurrentoutputfromtheoutputend,thusrealizingtheelectricity-optical-electricityconversion.Thisconversionisoftenappliedtovariouscivilindustrialproductssuchasswitchingpowersupplies,UPS,adapters,etc.Figure4.LM393MainsVoltageDetectionandControlTakeAC220Vasanexample.Inordertoprotecttheoptocoupler,weusea1Mresistorinthedesigntolimitthecurrentoftheoptocoupleremitter.TheoptocouplerchipsU1andU2arerespectivelyturnedonundertheactionofalternatingcurrent,andcooperatewiththecapacitorC6toensurethatthevoltageofthenon-invertinginputterminalU3isgreaterthantheinvertinginputterminalU4undertheconditionofnormalmainsinput.Theoptocouplerchipusedinthisdesigncanalsobeusedforelectricalisolationbetweenthecontrolboardandthemains.Whenthereismainspower:LM393snon-invertinginputterminalU3voltageisDC12VInvertinginputterminalU4voltageis9V(R2,R10dividedvoltage)ThecorrespondingoutputterminalishighThetransistor9014isturnedonTherelayoperatesThenormallyclosedpointisopenThereisoutputbetweenmainsvoltageWhenthereisnomainspower:Thevoltageatthenon-invertinginputterminalU3ofLM393isDC0VThevoltageattheinvertinginputterminalU4is9VThecorrespondingoutputterminalislowlevelThetransistor9014iscutoffTherelaydoesnotoperateThenormallyclosedpointisclosedTheinverteroutputs220V.IIITestAftertesting,thiscontrolcircuitmeetsthedesignrequirements:whenthereismainspowersupply,itoutputsmainsvoltage,andautomaticallyconvertstobackuppowersupplywithin10msinthecaseofmainspowerfailure,andhasgoodchargingmanagementfunctions,asshowninFigure5andFigure6.Figure5.LithiumBatteryVoltageDetectionWaveformFigure6.MainsVoltageDetectionWaveformInpracticalapplications,MOStubesandtriacscanalsobeusedtoreplacetherelaysinthevoltagedetectionandcontrolpartofthelithiumbatteryandtherelaysinthemainsvoltagedetectionandcontrolparttoachievethecontroloutput.IVConclsionThiscontrolboardisdesignedaccordingtothecharacteristicsofthelithiumbatterybackuppowersupplythatisgraduallypopularizedatpresent.Ithastheadvantagesofstronganti-interferenceandlowcost,andhasstrongmarketpromotionvalue.Insubsequentdesigns,wecanalsoaddprotectionfunctionssuchasbatteryunder-voltageprotection,short-circuitprotection,overloadprotection,over-voltageprotection,andover-temperatureprotectionaccordingtouserrequirementstocontinuouslyimprovetheproduct.Afterreadingtheblog,haveyoubetterunderstandLM393?Finally,ifyouhaveanyquestionsaboutLM393,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!

IntroductionInordertosolvetheproblemoftransientdistortion,thetypicalapplicationcircuitofLM3886poweramplifierischangedtothecurrentnegativefeedbacktype.Thecurrentsampleflowingthroughthespeakervoicecoilisfedbacktothepoweramplifierinputterminalviaresistance,andtheloudspeakersystemisalsoincludedinthefeedbacksystem.CatalogIntroductionCatalogITypicalpoweramplifiercircuitIIImprovedPowerAmplifierCircuitOrdering&QuantityITypicalpoweramplifiercircuitThepoweramplifiercircuitmadeofLM3886consistsoftwoparts:pre-amplifierandpoweramplifier.ThepreamplifierconsistsofanintegratedoperationalamplifierNE5534,whichprovidesavoltagegainofabout5times.ThepoweramplifieriscomposedofLM3886,whichprovidesavoltagegainofabout10times.Therefore,thefullpoweroutputcanbeachievedbyinputtingabout0.5Vsignalattheinputend.Figure1onlyshowstheLM3886dualpowersupplycircuit,whichcanalsoworkinasinglepowersupply.Consideringfromtheaspectofsoundquality,theaudioamplifiercircuitgenerallydoesnotusesinglepowersupply,butdualpowersupply.Figure1.typicalpoweramplifiercircuitThetypicalapplicationcircuitofLM3886adoptsthetraditionalnegativevoltagefeedbackmode.Negativevoltagefeedbackcanimprovethefrequencycharacteristicsofpoweramplifierandreducenonlineardistortion,butthesoundislackofstrength.Asthevolumeincreases,thelowfrequencywillbecometight,dryandhard,andthedistortionwillincrease.Atthesametime,thehighfrequencybecomessharpandharsh,andthemusicanditsdefinitionaregreatlyreduced.Thisistheso-calledTransientIntermodulationDistortion.Thetransientintermodulationdistortionismainlycausedbytheintroductionofdeepnegativefeedback.Voltagetypenegativefeedbackiseffectivetoimprovethenonlineardistortionofpoweramplifier,butitcannottakeintoaccountthetransientdistortionatthesametime.IIImprovedPowerAmplifierCircuitTheimprovedcircuitisshowninFigure2.Thelow-frequencyspectralgainofpoweramplifierisdeterminedbytheratioofR3andR4.C3andR5determinethehigh-frequencygainofpoweramplifier.DuetothelargecapacitancereactanceofC3atlowfrequency,thecurrentfeedbackisterminatedatlowfrequency,whilethehighfrequencyisimprovedbycurrentnegativefeedback.Theresultisthatthetotalbandwidthisimprovedandthetransientdistortionisgreatlyreduced.Theselectionoffeedbackcomponentsshouldbebasedontheimpedanceandinductanceoftheloudspeaker,sothatthelow-frequencygainis2-3timesofthehigh-frequencygain.Formerpoweramplifiersoftendesignedthefrequencycharacteristicstobeflat,whichdidnotachievegoodsoundeffects.Inordertoimprovethesoundeffectofthepoweramplifier,weshouldusethenegativefeedbackcircuittoconsciouslyincreasethelowfrequencygaintoachievethebesteffect,whichalsomeetstherequirementsofthelargedynamicsoundeffectoftodayshometheater.Figure2.schematicdiagramofpoweramplifiercircuitThesoundeffectofthismachineisexcellent.Thelowfrequencyextensionisincreasedanditisflexible.Thehighfrequencyisclearandsmooth.Theresolutionisgreatlyimproved,andthemetallicsoundiscompletelydisappeared.Evenifthevolumewasdoubled,nosignificantdistortionwasheard.IDescriptionIndatacollection,whentheamountofcollectionisrelativelylarge,theproblemofinsufficientSCMresourcesoftenoccurs.Inordertosolvethisproblem,thisblogcombinesthesituationofdatacollectionintheintegratedautomationsystemofsubstationsandproposesaverypracticalmethodusingCD4066electronicswitches.CatalogIDescriptionIIIntroductionIIIStructureof1CD4066ElectronicSwitchIVDesignofSwitchingCircuitBoardsinDataAcquisitionDevicesVImprovementofSwitchingCircuitBoardinDataAcquisitionDeviceFAQOrdering&QuantityIIIntroductionWhencollectingalternatingcurrentandvoltagesignals,itisgenerallytoconvertthesignalstobecollectedintolowervoltagesignalsthroughtransformers(CTandPT).ThenthroughtheA/Dconversiondevice,theanalogsignalisconvertedintoadigitalsignalandsenttothesingle-chipmicrocomputerforcollection.Butwhentherearemoredatachannelsthatneedtobecollected,thesituationbecomesmorecomplicated.Forexample,theautomaticdeviceoftheelectricpowersystem-thedigitalcentralizedmeasuringdeviceneedstocollect4groups,8groups,orevenmorepowermeasuringpoints.Ifeachpowermeasurementpointiscalculatedaccordingtotwocurrents(suchasAphaseandCphase,BphaseiscalculatedbyAandCphases),threevoltages(A,B,Cthreephases),pluspartofthe3U0voltage(3U0voltagereferstotheopendeltavoltageofthesecondarywindingofthetransformer,whichcanbeexpressedas3U0=Ua+Ub+Uc),itisnecessarytomeasuredozensofcurrentsandvoltages.IfeachchannelofmeasurementisequippedwithanA/DconversiondeviceandisdirectlyconnectedtotheMCUplug-in,thefollowingproblemsexist:Theresourcesoftheordinarysingle-chipmicrocomputerareinsufficient,andmultiplesingle-chipmicrocomputerboardsareneeded.ManyA/Dconversiondevicesarerequired,whichisnoteconomical.Theequipmentwillbehugeandwillnotmeettherequirementsofincreasinglyminiaturizeddigitalproducts.TheswitchboardmadeofCD4066electronicswitchproposedinthisblog.Undertheconditionofensuringmeasurementaccuracyandstability,therequiredA/Dconverterandmicrocontrollerresourcescanbereducedto1/2or1/4oftheoriginal.Atthesametime,becausetheCD4066chipisrelativelycheap,thecostoftherequiredswitchboardisrelativelylow.Atthesametime,inordertomeettherequirementsofmeasurementaccuracyandstability,thefollowingmeasuresweretakenduringthedesignprocess:(1)Usededicatedmeasurement-levelCTandPTforthetransformeroftheACplug-in(ACplug-in).TheCTmeasurementaccuracyishigh,andthecurrententersthelinearregionquickly.ThephaseshiftofCTandPTisverysmall(lessthan0.1degrees),whichmakestheaccuracyofpowermeasurementveryhigh.(2)Fortheanalog-to-digitalconversionplug-in,consideringthesizeoftheboardandactualapplicationneeds,12voltage/frequencyconverterswithexactlythesamecircuitstructureareusedtoconvertthe12-wayanalogoutputoftheswitchingplug-inintopulsefrequencywithinput.Theanalogquantityofamplitudechange.Andafterthefastoptocoupler(6N137)photoelectricisolation,itissenttothecounterintheCPUsystemforcountingtorealizetheanalog-to-digitalconversion.Thevoltage/frequencyconverterofthisplug-inadoptsthethird-generationVFCchip(VFC110),andthelinearrangeofitsvoltage-frequencycharacteristicis0~4MHz.ComparedwithAD654,thehighestconversionfrequencyof0.5MHzisincreasedby8times,whichgreatlyimprovestheaccuracyofanalog-to-digitalconversion.Moreover,theVFC110chiphasahigh-precisionbiasing5Vregulatedpowersupplyon-chip,whichcaneliminatetheneedforanexternalbiasregulatedpowersupplyandisveryconvenienttouse.(3)Alatch74LS374issetfortheanaloginputloopintheCPUplug-in,andthesignalfromtheVFCplug-inislatchedbytheclockgeneratedontheCPUchip.Oneofitsfunctionsistoturntheexternalasynchronouspulsesignalintoasynchronouspulsesignal,whichisbeneficialtocombatinterference;Thesecondfunctionistogetthepulseshapingfunction.Whenoneswitchingplug-inisneeded,thebasicimplementationprocessofthewholemeasurementisshowninFigure1.Whentwoswitchingplug-insareneeded,thebasicimplementationprocessisshowninFigure2.Figure1.SchematicdiagramofdatacollectionofoneswitchingboardFigure2.SchematicdiagramofdataacquisitionoftwoswitchingboardsIIIStructureof1CD4066ElectronicSwitchCD4066isanICcontainingfoursetsofanalogswitches,andthechipstructureisshowninFigure3.Figure3.StructurediagramofCD4066chipTheso-calledanalogswitchisacomponentthatcanusethedigitalsignalatthecontrolendtodeterminewhethertheanalogsignalattheinputendcanreachtheoutputend.CD4066analogswitch,bothendsofthesignalcanbeusedasinputoroutput.Inotherwords,ifoneendistheinputend,theotherendistheoutputend.Inaddition,thefrequencyresponseofCD4066isalsoverygood,upto1MHzormore.Therefore,youcanuseCD4066toswitchandmeasurethefour-channelanalogquantity.IVDesignofSwitchingCircuitBoardsinDataAcquisitionDevicesIntheactualmeasurementofpowersystemsubstations,itisoftennecessarytomeasurethehighandlowvoltagesidesorhigh,mediumandlowvoltagesidepowerofthetransformer.Eachgroupofpowerpointsneedstomeasuretwo-phasecurrent,three-phasevoltage,anditisalsopossibletomeasure3U0onthemainsideandthevoltageonthesideused.Therefore,6CD4066chipsarearrangedononeboardduringthedesign,eachofwhichisagroupof3,andatotalof24analogquantitiescanbemeasured.Thecontrolendsofeachgroupofchipswitchesareconnectedtogetherandcontrolledbyonesinglechip.BecausetheMCUandCD4066worklevelisdifferent.Therefore,thesingle-chipmicrocomputershouldbeisolatedbyphotoelectricisolator.Inthisway,the12switchesofeachgroupofchipscanbeturnedonandoffsimultaneouslyunderthecontrolofthesingle-chipmicrocomputer.Underthecontrolofthesinglechipmicrocomputer,whenonewayisdrivenhigh,theotherwayisdrivenlow.Thatis,onlyagroupof12analogquantitiesarecollectedeachtime,andthecollecteddataisplacedindifferentstoragelocationsofthesingle-chipmicrocomputerforprocessing.Inthisway,whenmeasuring24analogquantities,only12A/Dconvertersareneeded,andonly12analoginputresourcesoftheCPUplug-inareoccupied.Thepricepaidisonlyonemoreswitchingplug-in,whichachieveseconomicandefficientgoals.BecausetheworkingvoltageofCD4066is3~15V,inordertoensurethestabilityofwork,wetake+15V,-15Vvoltageand15Vgroundfromthepowerplugofthedevice.SupplypowertothetwoLM7809andLM7909three-terminalregulatorsoftheswitchingplug-inrespectively,andthe+8Vand-8VoutputfromthemarerespectivelysuppliedtotheCD4066.Theschematicdiagramoftheentireswitchingplug-inisshowninFigure4.Figure4.Switchplug-inschematicVImprovementofSwitchingCircuitBoardinDataAcquisitionDeviceIntheactualuseofthecircuitdesignedaccordingtoFigure4,someoftheswitchesoftheCD4066chipareoftendamaged,resultinginnomeasureddataorsoftconduction.Unplugthechip,plugitinagainorturnitoffandthenturnitonagain,anditpartiallyreturnstonormal.Later,itwasreplacedwithamilitary-grade4066chipandfoundthatthesituationdidnotimprove.Inthisregard,wehaveanalyzedandconductedvariousexperiments.Afterthetest,itisbelievedthattheACvoltagesignalconvertedfromCT/PTsometimeshasalargepeakvalue,evenexceedingtheworkingvoltageofthechip8V,andevenexceedingthesetvalueoftheACvoltage(thesetrangeis-5~+5V).Asaresult,someelectronicswitchesaredamagedorturnonsoftly.Takingintoaccountthecostandconvenienceofchanges,weadoptedaverysimplemethod.Thatis:ConnecttwodiodestotheinputofeachelectronicswitchofCD4066.Theforwardinputendofonediodeisconnectedtothe-8Vofthethree-terminalregulatorLM7909,andtheforwardoutputendoftheotherdiodeisconnectedtothe+8Vofthethree-terminalregulatorLM7809.Theinputterminalvoltageofeachelectronicswitchisclampedbetween-8Vand+8V,soastoprotecteachchanneloftheelectronicswitch.ThespecificconnectionisshowninFigure5.Figure5.Schematicdiagramoftheimprovedswitchingplug-inAtthesametime,inordertopreventdamagetotheCD4066chipduetotheunstableoutputofthethree-terminalregulator,asmallerresistorisconnectedtotheVDDandVSSterminalsofthechip.FAQWhatisCD4066?TheCD4066isaQuadBilateralSwitchIC,thatis,ithasfourswitcheswhichcanbecontrolledindividualusingacontrolpin.Theseswitchescanconductinboththedirectionsmakingitbilateral,itiscommonlyusedformultiplexinganalogordigitalsignals.HowtouseCD4066?TheCD4066ICconsistsoffourswitches.Itcanswitchanalogsignalsthroughdigitalcontrol.Ananalogsignalisappliedattheinputoftheswitch.IfaHIGHor1valueisfedintothecontrolinput,theanalogsignalwillbepassedfrominputtotheoutputofaswitch.HowCD4066work?The4066reallyfunctionsasananalogswitch.The4066isanICcomposedofswitcheswhicharedesignedtoswitchanalogsignalsviadigitalcontrol....The4066isaquadbilateralswitchcircuit,meaningthatiscomposedof4switches.Eachswitchhasasingleinputandasingleoutputterminal.WhataretheapplicationsofCD4066?TheCD4066isabi-directionalanalogswitchingICsimilartoCD4016,itiscommonlyusedinmultiplexingapplications;itcanalsobeusedtoisolatesignals.Theswitchisbilateralandhencecanbeusedforbothdigitalandanalogsignals.WhatsthedifferencebetweenCD4016andCD4066?ThemajordifferencebetweenbothisthatCD4066hasverylowinternalresistance,accordingtothedatasheetitcanonly5ofon-stateresistanceascomparedwith200ofCD4016IC.

I.DescriptionNowadays,LCD,VFD,LEDandotherdisplaydeviceshavebroughtinfinitecharmtointelligenthouseholdappliances.Atpresent,majorchipmanufacturershaveintroducedvariousdedicateddisplaydriverchips,theyhavebecomethemainstreamofdisplaydrivetechnology.However,thedisplayrequirementsofwhitegoodsarerelativelylow.Basedoncostconsiderations,thisarticleintroducesa74HC164-baseddisplaydrivecircuitdesignscheme,whichnotonlyachievesthesamedisplayeffect,reducescosts,butalsoimprovessystemreliability.74HC164CatalogI.DescriptionII.74HC164AdvantageAnalysisIII.74HC164ChipIntroductionIV.74HC164DisplayDriveCircuitV.74HC164DisplayCircuitDriverVI.ProcedureDescriptionFAQOrdering&QuantityII.74HC164AdvantageAnalysisUndernormalcircumstances,thedisplaycircuitofsmarthomeappliancesiscontrolledbyasingle-chipmicrocomputer,suchasthedisplayedcontentandthedisplaymode.Thesingle-chipmicrocomputerplaysanimportantroleinthecontrolcircuitofsmarthomeappliances.Itsselectionnotonlydeterminestherealizationofthecontrolcircuit,butalsohasagreatinfluenceonthecostofthecontroller.Weusetheserialinputandparalleloutputfunctionsofthe74HC164chiptocarryoutserialcommunicationwiththemicrocontroller,andtheparalleloutputportdirectlydrivesthedisplaydevice.ThissolutioncanexpandtheI/Oportofthesingle-chipmicrocomputerandreducetheresourcerequirementsofthesingle-chipmicrocomputer.Moreover,thechipinstallationmethodisveryflexible,whichcanreducethenumberofconnectingwiresofthedisplaypanel,improvethereliabilityofthesystem,andhasagreatercostadvantage.,Itiswidelyusedinbuttonsanddisplaydrivecircuits.III.74HC164ChipIntroduction74HC164isahigh-speedsilicongateCMOSdevice,whichispincompatiblewithlow-powerSchottkyTTL(LSTTL)devices.74HC164isan8-bitedge-triggeredshiftregister,serialinputdata,andthenparalleloutput.Dataisseriallyinputthroughoneofthetwoinputterminals(DSAorDSB);eitherinputterminalcanbeusedasahigh-levelenableterminaltocontrolthedatainputoftheotherinputterminal.Eitherconnectthetwoinputterminalstogether,orconnecttheunusedinputterminalstoahighlevel,sotheymustnotbeleftfloating.Thepindistributionof74HC164isshownasinFig.1.CompatiblewithTTLlevel,thehighestoperatingclockfrequencyis20MHz,thefan-outfactoris10,thepowerdissipationis500mW,andtheoutputcurrentIo(eachend)is25mA,whichcandirectlydriveLEDdisplaydevices.Figure174hc164pinoutAccordingtothelogicfunctionofthechip,thewaveformdiagramoftheinputandoutputsignalscanbeobtained,asshowninFigure2.TheoutputsignalsQ0~Q7aredelayedbyoneclockcyclerespectively,andcanform8scansignals.Figure274HC164signalwaveformIV.74HC164DisplayDriveCircuitThecircuitshowninFigure3isahybriddisplaycircuitcomposedoftouchswitches,nixietubesandLEDs.Amongthem,16buttons,2nixietubes,and8LEDsareatypical538scanningcircuit.The8pinsofthe74HC164chipQ0~Q7outputcolumnscansignals,andthemicrocontrollerdirectlyprovides5rowsofscansignals.Thesingle-chipmicrocomputerprovidesclockinputanddatainputsignalsfor74HC164tocontrolthedisplaycontent.Thecircuitrequires8pinsofthesingle-chipmicrocomputerintotal,whichsaves6pinresourcescomparedwiththeconventionalscanningcircuitandhascertaincostadvantages.DiodeD2-D23playsanisolationroletopreventthemutualinterferenceof74HC164chippinpotential.Forexample:whenachannelisselected,the74HC164outputpinsQ0~Q6arehighlevel,andQ7islowlevel.Atthistime,ifSW1andSW2arepressedatthesametime,pinQ7andpinQ6areinashort-circuitstate,whichwilldamagethechip.Clockinputpinsanddatainputpinsneedtobeconnectedtoceramiccapacitorstoresisthigh-frequencyinterference,butthecapacitanceshouldnotbetoolargetoavoidexcessivedistortionoftheinputwaveformandmakethecircuitunabletoworknormally.Itisrecommendedtouse100-1000pF.Figure3showsapracticalexampleofthecircuitV.74HC164DisplayCircuitDriverTakethe78K0Sseries8-bitMCUUPD78F9116fromNECCorporationofJapanasanexample,thedriverneedstodetect16,thenumberofkeystobedetected,thedisplaydrive28-segmentdigitaltubes,andthenumberofLEDs16(8expandedonthebasisofthereferencecircuit).Thesingle-chipmicrocomputerdirectlyprovides6linescansignals,andatthesametimeprovidesclockinputanddatainputsignalsfor74HC164tocontrolthedisplaycontent.TheIOportisdefinedasfollows:Eachsubroutinescans2groupsof31keys,andscansallkeyswithin8times.Displayscanchannelnumber0~3,displaytimeofeachchannel(1digitaltubeor1groupofLED)occupies1/4,andtherefreshcycledependsonthefrequencyofsubroutineexecution.Theprogrammustbeexecutedcyclically.Itcanbecalledasaregularsubroutineordirectlyembeddedinthemainprogramfile.Itismoreappropriatetoexecuteitevery1~3mS.Theconfirmationtimeforabuttontobeliftedorpressed(24mS~32mS)--(72ms~96mS),theresponsespeedcanmeetpeoplesoperatinghabits,thedisplayrefreshfrequencyissetto250Hz--83Hz,ifitislowerthan40~50HzFlashing.TheprogramflowchartisshowninFigure4.Figure4ProgramflowchartVI.ProcedureDescription(1)ExternalnameandglobalvariabledeclarationFAQHowdoesthe74HC164transmitdatainthemicrocontrollercircuit?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.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!

IDescriptionWhatisLM2596?LM2596isaswitchingvoltageregulatorforstep-downpowermanagementmonolithicintegratedcircuits,capableofoutputting3Adrivecurrent,whilehavinggoodlinearityandloadregulationcharacteristics.ThefixedoutputversionsofLM2596are3.3V,5Vand12V,andtheadjustableversioncanoutputvariousvoltageslessthan37V.Withonlyafewexternalcomponents,wecanusethisvoltageregulator!Moreover,theLM2596switchingfrequencyis150KHz,whichmeansthatcomparedwithlow-frequencyswitchingregulators,wecanusesmallerspecificationsoffiltercomponents.Inaddition,LM2596integratesfrequencycompensationandfixedfrequencygenerator.Thisblogwillintroduce4typicalapplicationcircuitsofLM2596.Figure1.LM2596CatalogIDescriptionIICircuitofLM2596Output3.3V,5VIIICircuitofStep-DownVoltageRegulatorsIVLM2596ApplicationCircuitVLM2596AdjustableCurrentLimitingRegulatorFAQOrdering&QuantityIICircuitofLM2596Output3.3V,5VHaveyounoticedthatinthedesignbelow,allLM2596chipschooseasupplyvoltageof5V,3.3Vor1.8V?Thisisbecause,inthedesignofthewholecontrolsystem,ifthepowersupplysystemistoocomplexandredundant,itwillnotonlycauseelectromagneticinterferencetootherpartsofthecircuit,butalsotheeconomicbenefitisnotgood.Therefore,theselectionof5V,3.3Vor1.8Vsupplyvoltageisbeneficialtotheexperimentaldesign.Whataretheotherbenefits?Inthisway,the24Vvoltagecanbedirectlyconvertedintothedesiredvoltagebyusing3LM2596andsomecapacitors,inductors,diodesandsoon.Thiskindofdesigncircuitisnotonlysimpleandconvenient,butalsoveryeconomical.ThepowersupplycircuitisshowninFigure2.Whenweuseit,wecanchoosethechipsofLM2596+5V,LM2596+3.3VandLM2596+1.8Vaccordingtoourneeds:Toobtaintheconnectionofgraph(a)when+1.8Vand+5V,Toobtaintheconnectionofgraph(b)when+3.3V.Figure2.LM2596CircuitDiagramIIICircuitofStep-DownVoltageRegulatorsWhenyouthinkaooutthevoltageregulatorandstep-downmoduleinthesingle-chipmicrocomputersystem,willyouthinkofcommonchipssuchasLM7805andAMS117?SinceLM7805andAMS117arelowincostandcanbeuseddirectlywithoutexternalexpansionofothercomponents,theyhavebeenwidelyused.ButdontforgetthatLM7805hasafataldisadvantage:highheatgenerationandlowoutputcurrent.Inthemicrocontrollersystem,iftheexternaldevicecurrentisverysmall,thenitsOKtochooseLM7805.However,onceweneedtodrivemoduleswithlargercurrentssuchasrelays,LM7805appearstobepowerless,becausehighheatgenerationmeanspowerloss.Inaddition,iftheinputvoltageofLM7805isabout15V,evenifthecurrentrequiredfortheoutputloadissmall,itsheatgenerationisabout85℃(Ithinkthisshouldbeabletofryanegg),soaheatsinkoracoolingfanmustbeaddedtoit.ThismeansthatcostandPCBlayoutwillbeaffected.TheLM2596seriesofregulatorsaremonolithicintegratedcircuitsthatprovidealltheactivefunctionsforastep-down(buck)switchingregulator,capableofdrivinga3-Aloadwithexcellentlineandloadregulation.Thesedevicesareavailableinfixedoutputvoltagesof3.3V,5V,12V,andanadjustableoutputversion.However,itshouldbenotedthatbecauseLM2596isaswitchingvoltageregulator,itsowncalorificvalueisverysmall.ThismeansthatthewideinputvoltagerangecomparedwiththeLM7805,LM2596needstoaddseveralexternalcomponents.Figure3.LM2596Step-DownVoltageRegulatorsFromtheabovefigure,wecanseethatcomparedwithLM7805,LM2596has4moreexternalcomponents,anditsoutputcurrentcanreach3Aatmost,whichisenoughtodealwithcommonsingle-chipmicrocomputersystems,atthesametime,theinputvoltagerangeiswideandthemaximuminputvoltageis40V.LM2596alsohasanadjustableversion.Iftheadjustableversionisusedtomakea0-30vhigh-currentadjustablepowersupply,itiscompletelyfeasible.Figure4.AdjustableLM2596TheabovefigureisacircuitdiagramofanadjustableversionofLM2596,whichcanoutputaDCvoltageof0-37v,whichismuchbetterthanLM317.IVLM2596ApplicationCircuitLM2596supportsadjustableoutput.Whentheinputis40V,theoutputcanbecontinuouslyadjustedto0~37V.Thetypicalapplicationcircuitisasfollows:Figure5.LM2596ApplicationCircuitNote:Thefeedbackwireshouldbefarawayfromtheinductance,andthethickwireinthecircuitmustbeshort.Herewedbettershielditwithagroundwire.TheresistorsR1andR2thatregulatetheoutputvoltageshouldbeclosetothe4pinsoftheLM2596.VLM2596AdjustableCurrentLimitingRegulatorLM2596doesnothavethefunctionofcurrentlimiting,butinsomeelectronicdesignsandauxiliaryequipment,thereisacertaindemandforthefunctionofcurrentlimiting.Althoughthestandardapplicationcircuitgivenbythemanufacturercannotaccomplishthisfunction,wecanaddafunctioncircuittomakeitrealizethecurrentlimitingfunction.AsshowninFigure6:Figure6.LM2596AdjustableCurrentLimitingRegulatorFAQWhatislm2596?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.IDescriptionThisbloghasdesignedastep-downDCswitchingpowersupply(itsvoltagecanbeadjustedfrom0V)forneutrontubestorage.ThepowersupplyadoptstheBUCKtopology,andtherail-to-railLMV358operationalamplifiervoltagefeedbackcircuitisdesignedtocooperatewiththeLM2596internalerroramplifiertoovercometheshortcomingsthattheminimumoutputvoltageoftheLM2596step-downchipcannotbelowerthan1.2V,therebytheoutputvoltagecanbeadjustedfrom0V.ThisvideoreviewsanLM2596DCtoDC,adjustable,stepdownregualtorCatalogIDescriptionIIIntroductionIIILM2596BasicCircuitIVDesignofZero-startingPeripheralCircuit4.1VoltageReferenceCircuit4.2VoltageFeedbackCircuitVPowerInductorParameterVIAnalysisofExperimentalResultsVIIConclusionFAQOrdering&QuantityIIIntroductionBeforewestartreadingthisblog,pleasetakeafewsecondstolookatthefollowingtwoquestions:①Whatistheneutrontubestorage?②WhatistherelationshipbetweentheneutrontubestorageandtheDCpowersupplythatrequiresthevoltagecanbeadjustedfrom0V?Figure1.LM2596Whatistheneutrontubestorage?Neutrontubestorageisgenerallycomposedofpowderwithstronghydrogenabsorptioncapacityandheatingwire,usedtostoredeuteriumandtritiumgasfornuclearfusionreaction.Bycontrollingthecurrentoftheheatingwire,theoutgassingvolumeofthereservoirandtheairpressureinthetubeareindirectlycontrolled,therebycontrollingtheneutronyield.Itscoldresistanceofthereservoirisabout3.Whenthepassingcurrentreaches0.35A,thereservoirstartstoreleasedeuteriumandtritiumgas.Theadditionoftheionsourcevoltagewillionizethegasintheionsource,andtheaccelerationhighvoltagewillcausetheionizeddeuterium-tritiumionsintheionsourcetobeextractedandaccelerated,andadeuterium-tritiumfusionreactionoccursonthetargettoproduceneutrons.WhatistherelationshipbetweentheneutrontubestorageandtheDCpowersupplythatrequiresthevoltagecanbeadjustedfrom0V?Inordertoaccuratelycontroltheheatingcurrentofthestorage,thepowersupplyoftheneutrontubestoragerequiresthatthevoltagecanbeadjustedfrom0V.Afterwetookaquicklookatoneofthecircuitprotagonists,neutrontubestorage,discussedinthisblog,letstakealookatanotherequallyimportantrole:theLM2596chip.ThevoltagereferenceoftheLM2596integratedvoltageerroramplifieris1.2V,sothatitslowestoutputvoltageisnotlessthan1.2V.ItseemsthattheLM2596chipitselfcannotbeadjustedfrom0V?Howcanthisdefectberesolved?Wecanusetherail-to-railopampLMV358poweredbyasinglepowersupplytodesignthevoltagefeedbackcircuit.Byisolatingthesamplingterminalandthefeedbackterminal,thelinearadjustmentintervaloftheopampcanbeusedtocompensateforthevariationofthefeedbackvoltage,whichcansolvetheproblemofthelowestoutputofLM2596thatcannotbelowerthantheproblemcausedby1.2V.Afterexperimentaltests,thedesignofthepowersupplyfeedbackcircuitissimpleandefficient.Notonlythepoweroutputvoltagecanbeadjustedfromzero,butalsotheoutputvoltageadjustmentaccuracyishigh,sotheactualapplicationneedscanalsosolved.IIILM2596BasicCircuitLM2596isavailableinfixedandadjustableversions.Amongthem,theoutputvoltageoftheadjustableversionrangesfrom1.2vto37V,withthemaximuminputvoltagedoesnotexceed45V.Underloadconditions,thecircuitshowsthefollowingcharacteristics:Voltageregulation4%.Donotneedtoomanycomponentsforperipheralcircuits.Lowpowerbypassmode.Thetypicalstaticcurrentis80A.LM2596minimumoutputvoltage1.2VapplicationcircuitisshowninFigure2.AscanbeseenfromFigure1,thefeedbackresistorsR1andR2determinethevoltagedividerratioofthepowersupplyoutputvoltage,whichcanbeadjustedthroughadjustingR1.WhenR1isadjustedto0,theoutputvoltageistheminimum,whichistheinternalvoltagereferenceoftheLM2596chip.Figure2.LM2596BasicCircuitTheinternalvoltagereferenceatthefeedbackendoftheLM2596chipis1.2V,whichlimitstheoutputvoltageofthepowersupplytobeadjustedfromzero.IVDesignofZero-startingPeripheralCircuitFirst,trytoconnecttheFBterminalandtheVsterminalinFigure1,andadjusttheR1resistanceto0.Atthistime,theVoutisatleast1.2V.Whatshouldwedotoachievethepurposeofadjustingfromzero?WecandisconnectVs,designanindependentvoltagefeedbackcircuittoadjusttheFBterminalvoltage,andchangetheerrorvariationoftheLM2596internalvoltageerroramplifierthroughtheexternalinputvoltagetoincreaseordecreasethePWMoutputdutycycle,whichinturnenablestheoutputvoltagetobeadjustedfromzero.4.1VoltageReferenceCircuitSo,howtoensurethattheFBterminalvoltageofU1isaround1.2V?Sincethesamplingvoltagefeedbackterminalneedsavoltageregulatorforcompensation,wecanuseasimplifiedcircuitdesignmethod,thatis,usingTL431toachievethisgoal.WhatisTL431?TL431hasthefollowingcharacteristics:TL431isatypicalthree-terminalprecisionvoltageregulatorTheoutputvoltagefrom2.5to36Vcanbearbitrarilysetwith2resistorsItsdynamicimpedanceis0.2Theaccuracyofthevoltagereferenceis0.6%ThevoltagereferencecircuitbasedonTL431isshowninFigure3.Figure3.TL431VoltageReferenceCircuitInthiscircuit,thevoltagereferencehavetwofunctions:itcanbothbeusedastheexternalinputvoltagereferenceandthecompensationvoltageofopampinphase.Theexternalinputvoltageisusedtochangetheoutputvoltage,whilethecompensationvoltageisusedtocompensateforthechangeinvoltageatthefeedbackterminal.4.2VoltageFeedbackCircuitThenon-invertingendofU1sinternalvoltageerroramplifierisintegratedwitha1.2VvoltagereferenceandtheoutputvoltagefeedbackresistorR2isconnectedtotheinvertingendoftheerroramplifier:Whenthevoltageatthefeedbackterminalisgreaterthan1.2V,theerroramplifiergeneratesanegativeerrorsignal,thePWMoutputdutycycledecreases,andtheoutputvoltagedecreases;Whenthevoltageatthefeedbackterminalislessthan1.2V,theerroramplifiergeneratesapositiveerrorsignal,thePWMoutputdutycycleincreases,andtheoutputvoltageincreases.Regardlessofwhethertheoutputvoltageofthepowersupplybecomeslargerorsmaller,thechipcankeeptheoutputvoltagestablebycontrollingtheontimeoftheswitchtube,buttheminimumoutputvoltageis1.2V.ThevoltagefeedbackcircuitdesignedbyLMV358isshowninFigure4.Figure4.LMV358VoltageFeedbackCircuitHereisaquestion:Whatisthekeytorealizetheoutputvoltageadjustmentfromzero?Infact,itisverysimple.ThekeyiswhetherthelowestvoltageofFBintheoperationalamplifierfeedbackcircuitcanbe0V.Inthecaseofasinglepowersupply,theopamphasintegratedtransistors,anditsminimumoutputvoltageisabout0.6V(whichobviouslydoesnotmeettheaboverequirements).Ifwewanttosolvethisproblem,wecanchooseLMV358opamppoweredbyrail-to-railsinglepowersupply,withaminimumoutputvoltageof65mV,soastomeettherequirementofpoweradjustmentfromzero.make:M=R14/R13N=R16/(R16+R18)Q=R19/R20Thenthevoltagefeedbackcircuitparametersarecalculatedasfollows:(1)Vo1=Vs(2)Vo2=(1+M)Vref-VadM(3)Vo3=N(Vo1+Vo2)(1+Q)(4)Vo4=kVo3=VfbIntheaboveformula:kisavariablecoefficient.LetFB=1.2V.Whenthepowerisinitiallypoweredon,Vad=0V,Vref=2.5V,buttheoutputvoltageoftheoperationalamplifierdoesnotnecessarilymeetFB=1.2V,causingLM2596tomalfunction.Inordertoavoidthissituation,wecanuseR21tocorrectthevoltagevalueofVfbattheinitialpower-on,sothatFB=1.2V.IncreasetheVadterminalvoltage,theVo2terminalvoltagedecreasesandtheoutputvoltageincreases,sothatVo1increases.Conversely,Vo2compensatesthevariationofVo1toensurethatthevoltageatthefeedbackterminalofthechipisequalto1.2V,sothatthesamplingvoltageVsfollowsthechangeoftheVadvoltage,andthepowersupplycanbeadjustedfromzero.ThetestdataofthevoltagefeedbackcircuitisshowninTable1.Table1.TestDataFromtheabovetestdata,wecanseethatwecanmakeuseofthelinearoutputcharacteristicsoftheoperationalamplifiertoachievethepurposeoflinearadjustmentoftheoutputvoltage.TheVschangeswiththeVad,thechipreferenceterminalvoltageVfbremainsunchanged,andtheoutputvoltagerangeisdeterminedbytheresistancepartialvoltageratio.Undertheconditionoffullload,whentheVadinputvoltagechangesfrom0to5V,thesamplingresistorVsterminalvoltageoutputrangecanbe0to5V,andthepowersupplyoutputvoltageisadjustablefrom0to35Vthroughtheresistordividerratio.VPowerInductorParameterThereare3operatingmodesfortheinductorcurrentintheBUCKcircuit.ThisblogdesignstheinductoraccordingtotheCCMworkingstate,andfine-tunestheinductorparametersaccordingtotheactualtestresults.Whenthepowertubeisturnedon,theinductorcurrentriseslinearly,andthecurrentincrementexpressionis:(5)ION=(VONTON)/LVON,TON,andLaretheinductorconductionvoltage,turn-ontimeandinductance,respectively.Thecurrentdecrementintheturn-offphaseofthepowertubecanbeexpressedas:(6)IOFF=(VOFFTOFF)/LVOFFandTOFFaretheinductorvoltageandturn-offtimewhenturn-off.Inaswitchingcycle,theincrementanddecrementoftheinductorcurrentareequal,andthevolt-secondlawcanbeusedtoobtain:(7)VONTON=VOFFTOFFInthebucktopology,VON=VIN-VO,VOFF=VO,theaboveformulaistransformedtoderivethedutycycleequationofBUCKtopologywork:(8)D=VO/VINHowtodeterminethedutycycle?Thepowersupplyinputvoltageisafixedvalueof40V,andtheoutputvoltagerangeis0-35V.Fromthis,thedutycycleD=0-0.875canbecalculated.Here,wedesigntheinductorparametersaccordingtotheprincipleofmaximumdutycycleandmaximumoutputpower.SohowisILdetermined?ThemaximumloadcapacityofLM2596is3A.FortheBUCKtopology,theaverageinductorcurrentILisequaltotheloadcurrentIO.Wecansetthecurrentrippleratertobe0.3,andthechoiceofraffectsdeviceselectionandcircuitcost.Theexpressionofrisdefinedasfollows:(9)r=I/ILIntheaboveformula:Iisthechangeoftheinductorcurrentinaperiod,andtheparametersaresubstitutedintotheaboveformulatoobtainI=0.9A.Accordingtothelawofelectromagneticinduction,theinductanceiscalculatedasthefollowingformula:(10)L=(VOND)/(rILf)ItisknownthattheswitchingfrequencyoftheLM2596chipis150kHz,andthecalculatedparametersaresubstitutedintotheaboveformulatocalculateL=259H.Intheactualdebugging,thetheoreticallycalculatedinductanceparameterscannotmeetthepracticalapplicationrequirements.Accordingtotheactualdebuggingresults,thehighfrequencypowerinductorwithratedinputcurrent4Aandinductancevalue330Hisselected.VIAnalysisofExperimentalResultsMakeaprototypeaccordingtothedesignparameters.Undertheconditionoffullload,given40Vinputvoltage,theoutputvoltageofthepowersupplyunderdifferentinputvoltageismeasuredbyadjustingtheexternalVadvoltage.Table2showstheoutputvoltagetestdataatload10.1.Inpracticalapplication,theefficiencyofpowersupplyisthefirstconcern.Table3showsthedataformeasuringvoltageandcurrentattheinputandoutputofthepowersupply,respectively.Ascanbeseenfromtables2and3,theinputandoutputvoltagesareproportionaltoeachother,andtheregulationaccuracyoftheoutputvoltageisabout0.05V.Theoutputvoltageofthepowersupplycanbeadjustedfromzero,whichsolvesthedeficiencyof1.2VofthelowestoutputvoltageoftheLM2596chip.Usingtheabovecalculationmethod,theaverageefficiencyofthepowersupplyis93.44%.Usingthetestdataunderno-loadandfull-loadconditions,itiscalculatedthattheloadadjustmentrateofthepowersupplyat35Voutputis1.3%.Inaddition,thepowersupplycannotonlyworkforalongtime,thetemperatureriseisnormal,butalsotheperformanceisstable.Table2.TestData:LM2596DCRegulatedPowerSupply(10.1)Table3.TestData:LM2596DCRegulatedPowerSupplyEfficiencyVIIConclusionInordertosolvetheshortcomingthattheoutputvoltageofLM2596cannotbeadjustedfromzero,thisblogadoptsthemethodofisolatingthesamplingvoltageandthefeedbackendofthechiperroramplifier,thatis:avoltagefeedbackcircuitbydesigningarail-to-railopamptomaketheoutputvoltagecapableofadjustingfromzero.Inaddition,weanalyzedthedesignoftheinductanceparametersoftheadjustableBUCKpowersupplyinprinciple,andmakeaprototypeaccordingtotheparameterstoverifythecorrectnessandreliabilityofthedesign.Theexperimentalresultsshowthattheloadadjustmentrateofthepowersupplyis0.88%,themaximumworkingefficiencyunderratedloadis95.08%,andthefullloadpoweris105W,whichcanmeettheneedsofpracticalapplications.FAQWhatislm2596?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.

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