Tkool Electronics

DescriptionTL494wasdesignedandlaunchedbyTexasInstrumentsintheearly1980s.Itwaswidelyacceptedbythemarketimmediatelyafteritwaslaunched,especiallyontheATXhalf-bridgepowersupplyofPCs.Untiltoday,aconsiderableproportionofPCpowersuppliesarestillbasedontheTL494chip.HowtoTestTL494NCatalogDescriptionComponentDatasheetTL494PinoutTL494ParameterFeaturesAdvantagesApplicationsTL494SimplifiedBlockDiagramTL494PackageandPinsFunctionalBlockDiagramWheretouseTL494HowtouseTL494TL494TypicalApplicationFAQOrdering&QuantityComponentDatasheetDatasheetTL494Pulse-Width-ModulationControlCircuitsdatasheet(Rev.H)Applicationnotes1IsolatedMultipleOutputFlybackConverterDesignUsingTL494Applicationnotes2DesigningSwitchingVoltageRegulatorsWiththeTL494(Rev.E)TL494PinoutPinDescriptionNameNO.1IN+1Noninvertinginputtoerroramplifier11IN2Invertinginputtoerroramplifier12IN+16Noninvertinginputtoerroramplifier22IN-15Invertinginputtoerroramplifier2C18CollectorterminalofBJToutput1C211CollectorterminalofBJToutput2CT5CapacitorterminalusedtosetoscillatorfrequencyDTC4Dead-timecontrolcomparatorinputE19EmitterterminalofBJToutput1E210EmitterterminalofBJToutput2FEEDBACK3InputpinforfeedbackGND7GroundOUTPUTCTRL13Selectssingle-ended/paralleloutputorpush-pulloperationREF145-VreferenceregulatoroutputRT6ResistorterminalusedtosetoscillatorfrequencyVCC12PositiveSupplyTL494ParameterTopologyBoost,Buck,Flyback,Forward,Full-Bridge,Half-Bridge,Push-PullControlmethodVoltageVCC(Min)(V)7VCC(Max)(V)40Dutycycle(Max)(%)45UVLOthresholdson/off(V)Frequency(Max)(kHz)300Operatingtemperaturerange(C)-40to85,0to70Gatedrive(Typ)(A)0.2FeaturesAdjustableSwitchingFrequency,DeadTimeControl,ErrorAmplifier,Multi-topologyRatingCatalogFeaturesCompletePWMPower-ControlCircuitryUncommittedOutputsfor200-mASinkorSourceCurrentOutputControlSelectsSingle-EndedorPush-PullOperationInternalCircuitryProhibitsDoublePulseatEitherOutputVariableDeadTimeProvidesControlOverTotalRangeInternalRegulatorProvidesaStable5-VReferenceSupplyWith5%ToleranceCircuitArchitectureAllowsEasySynchronizationAdvantagesTheTL494deviceincorporatesallthefunctionsrequiredintheconstructionofapulse-width-modulation(PWM)controlcircuitonasinglechip.Designedprimarilyforpower-supplycontrol,thisdeviceofferstheflexibilitytotailorthepower-supplycontrolcircuitrytoaspecificapplication.TheTL494devicecontainstwoerroramplifiers,anon-chipadjustableoscillator,adead-timecontrol(DTC)comparator,apulse-steeringcontrolflip-flop,a5-V,5%-precisionregulator,andoutput-controlcircuits.Theerroramplifiersexhibitacommon-modevoltagerangefrom0.3VtoVCC2V.Thedead-timecontrolcomparatorhasafixedoffsetthatprovidesapproximately5%deadtime.Theon-chiposcillatorcanbebypassedbyterminatingRTtothereferenceoutputandprovidingasawtoothinputtoCT,oritcandrivethecommoncircuitsinsynchronousmultiple-railpowersupplies.Theuncommittedoutputtransistorsprovideeithercommon-emitteroremitter-followeroutputcapability.TheTL494deviceprovidesforpush-pullorsingle-endedoutputoperation,whichcanbeselectedthroughtheoutput-controlfunction.Thearchitectureofthisdeviceprohibitsthepossibilityofeitheroutputbeingpulsedtwiceduringpush-pulloperation.TheTL494Cdeviceischaracterizedforoperationfrom0Cto70C.TheTL494Ideviceischaracterizedforoperationfrom40Cto85C.ApplicationsDesktopPCsMicrowaveOvensPowerSupplies:AC/DC,Isolated,WithPFC,90WServerPSUsSolarMicro-InvertersWashingMachines:Low-EndandHigh-EndE-BikesPowerSupplies:AC/DC,Isolated,NoPFC,90WPower:Telecom/ServerAC/DCSupplies:DualController:AnalogSmokeDetectorsSolarPowerInvertersTL494SimplifiedBlockDiagramTL494PackageandPinsPackagePinsSizePDIP(N)16181mm19.3x9.4SOIC(D)1659mm9.9x6SOP(NS)1680mm10.2x7.8TSSOP(PW)1622mm4.4x5FunctionalBlockDiagramWheretouseTL494TheTL494fixedfrequencyPWMControllercanbeusedforDCtoDCconversionregardlessofbuckorboosttopology.TL494canbeusedtoprovideaconstantcurrentbyvaryingtheoutputvoltagetotheload.ThisICfeatureanoutputcontrolcircuit,aflipflop,adeadtimecomparator,twodifferenterroramplifiers,a5Vreferencevoltage,anoscillator,andaPWMcomparator.SoifyouarelookingforanICtoproducePWMsignalsforcontrollingapowerswitchbasedonthecurrentflowingthroughthecircuit,thenthisICmightbetherightchoiceforyou.HowtouseTL494AtestcircuitfromtheTL494datasheetisshownbelow.NoninvertingpinsareconnectedtotheRefpinwhileinvertingpinsareconnectedtotheground.TestinputsaregiventoDTCandFEEDBACKpins.Externalcapacitorandresistorareconnectedtopin56tocontroltheoscillatorfrequency.Theerroramplifiercomparesasampleofthe5-VoutputtothereferenceandadjuststhePWMtomaintainaconstantoutputcurrentTL494TypicalApplicationSwitchingandControlSectionsInputPowerSourceError-AmplifierSectionCurrent-LimitingCircuitSoft-StartCircuitSwitchingCircuitPower-SwitchSectionFAQWhatisTL494?TL494isaPWMcontrollerICusedforpowerelectronicscircuits.Itcomprisesofon-chiptwoerroramplifiersanoscillatorwithadjustablefrequencyfeature,anoutputflip-flophavingpulsesteeringcontrol,andanoutputcontrolcircuitwithfeedback.WhatisthedetaileddescriptionofTL494?TheTL494deviceincorporatesallthefunctionsrequiredintheconstructionofapulse-width-modulation(PWM)controlcircuitonasinglechip.Designedprimarilyforpower-supplycontrol,thisdeviceofferstheflexibilitytotailorthepower-supplycontrolcircuitrytoaspecificapplication.TheTL494devicecontainstwoerroramplifiers,anon-chipadjustableoscillator,adead-timecontrol(DTC)comparator,apulse-steeringcontrolflip-flop,a5-V,5%-precisionregulator,andoutput-controlcircuits.Theerroramplifiersexhibitacommon-modevoltagerangefrom0.3VtoVCC2V.Thedead-timecontrolcomparatorhasafixedoffsetthatprovidesapproximately5%deadtime.Theon-chiposcillatorcanbebypassedbyterminatingRTtothereferenceoutputandprovidingasawtoothinputtoCT,oritcandrivethecommoncircuitsinsynchronousmultiple-railpowersupplies.Theuncommittedoutputtransistorsprovideeithercommon-emitteroremitter-followeroutputcapability.TheTL494deviceprovidesforpush-pullorsingle-endedoutputoperation,whichcanbeselectedthroughtheoutput-controlfunction.Thearchitectureofthisdeviceprohibitsthepossibilityofeitheroutputbeingpulsedtwiceduringpush-pulloperation.WhatareTL494productfeatures?CompletePWMPower-ControlCircuitryUncommittedOutputsfor200-mASinkorSourceCurrentOutputControlSelectsSingle-EndedorPush-PullOperationInternalCircuitryProhibitsDoublePulseatEitherOutputVariableDeadTimeProvidesControlOverTotalRangeWhatisPWMIC?TheTL494fixedfrequencyPWMControllercanbeusedforDCtoDCconversionregardlessofbuckorboosttopology....ThisICfeatureanoutputcontrolcircuit,aflipflop,adeadtimecomparator,twodifferenterroramplifiers,a5Vreferencevoltage,anoscillator,andaPWMcomparator.HowdoesPWMICwork?Asitsnamesuggests,pulsewidthmodulationspeedcontrolworksbydrivingthemotorwithaseriesofON-OFFpulsesandvaryingthedutycycle,thefractionoftimethattheoutputvoltageisONcomparedtowhenitisOFF,ofthepulseswhilekeepingthefrequencyconstant.WhichICisbetterforabuckconverter,TL494orUC3843?TheymainlydifferintypeofcontrolTL494=voltagemodecontrol(Oneloopcontrol).whileUC3843usescurrentmodecontrol(Nestedloopcontrol,withainner/fastcurrentloopandanotherouter/slowervoltageloop)Typicallyvoltagemodeareusedinmultipleoutputconverterswithgoodcross-regulation.CurrentmodewhenyouwanttoparallelmultipleconverterstomakeasingleconverterwithhighercurrentratingTL494isaverypopularIC.IfyouhavesimplerequirementsTL494isrecommendedHowdoIproperlysetthefeedbackpinonaTL494SMPSIC?Thefeedbackpinistheoutputofbotherroramplifiers,usedincomparingandadjustingtheoutputpulsewidthtotheDCcontrolvoltage.OnvariouscircuitsIhavelookedup,theop-ampconnectedtopins23areusedtosetthegainofthefeedbackloop,using2resistorswithoneresistorconnectingto2.5Vpotentialdivideron5Vreferencevoltage.Withtheotherconnectingtotheoutput(viasuitableisolation)Thegainappearstobesetat101,usinga51kfeedbackwith510ohmstothe2.5Vreference.Itisusedtocontrolthegainofthefeedbackvoltage.NoliteratureIhaveyetfound,givesanindicationonhowthisgainbeset,exceptagraphshowinganopenloopgainof1000,presumablythegainissetforthebeststability,althoughtherewillalsobeatimeconstant.WhyistherenofrequencycompensationrequiredinTIsTL494examplebuckregulatordesign(operationalamplifier,buckphase,shiftphase,margin,TL494,electronics)?ItsafixedfrequencyPWMcontrollerwithinternaldeadtimetimer.Frequencycompensationisnotrequired.Takealookatthedatasheet.HowtouseTL494?

IRFBF20SPBF-VISHAY

FreenoveQuadrupedRobotKit TheFreenoveQuadrupedRobothasaverycooldesigntoit.

SMBJ14A-E3/52-VISHAY

WPAorWPA2securedconnection.

SN7476N

Quimat37-in-1SensorModuleStarterKitswithTutorialsforArduinoSensormodulestarterKitisspeciallydesigned

PF3FSX

Thehangingmagnetandthekickstandaregreatstorageutilitiesandmakethemeasurementprocesshasslefree.

DDR2DDR3

choosingaheadsetwiththisfeatureismust.

VS-10ETF12-M3-VISHAY

Itsavesyourtimebymakingtheconnectionseasyandworkseffectively.

LM79L05

thepeakmodeofa120VAClinewillbe+169Vto-169V.

SN74LS244N

INLIFE81in1ProfessionalElectronicsMagneticDriverKitNextonourlistisatoolkitwithover81toolsinone.

OMAPL137

ControllingaServoMotorwithSTM32F103C8T6BluePillBluetoothControlledServoMotorusingArduino.

DMSFS3

Voltageandcurrentreadingsarefixed.

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