UC3842BD

COS UC3842, 3843, 3844, 3845
www.cosine-ic.com 1Features
8-Vto30-VOperation
LowStart-upCurrent:<1mA 5.1-VReferenceTrimmedto1% CurrentModeOperationupto500KHz AutomaticFeed-forwardCompensation Under-voltageLockoutWithHysteresis LatchingPWMforCycle-by-CycleCurrent Limit Double-PulseSuppression HighCurrentOutputDriver Optimizedforoff-lineandDC-to-DC Converters AvailablePackaging: SOP8/TSSOP8/DIP8 Applications SolarInverters SwitchingRegulatorsofAnyPolarity MotorControl BatteryChargers DC/DCPowerSupplies PinDiagram Rev1.0 Copyright@2018CosineNanoelectronicsInc.Allrightsreserved Theinformationprovidedhereisbelievedtobeaccurateandreliable.CosineNanoelectronicsassumes noreliabilityforinaccuraciesandomissions.Specificationsdescribedandcontainedherearesubjected tochangewithoutnoticeonthepurposeofimprovingthedesignandperformance.Allofthisinformation describedhereinshouldnotbeimpliedorgrantedforanythirdparty.GeneralDescription TheCOSUC384xseriesofcontrollersare peakcurrentmodepulsewidthmodulators. Theyaredesignedtoofferimproved performanceandloweredexternalpartscount whenusedindesigningoff-lineorDC-to-DC switchingpowersupplies.Theinternally implementedcircuitsincludeanunder-voltage lockout(UVLO),featuringastart-upcurrentof lessthan1mA,andaprecisionreference trimmedforaccuracyattheerroramplifierinput. Otherinternalcircuitsincludelogictoensure latchedoperation,apulse-widthmodulation (PWM)comparatorthatalsoprovides current-limitcontrol,andatotem-poleoutput stagethatisdesignedtosourceorsink high-peakcurrent.Theoutputstage,suitable fordrivingN-channelMOSFETs,islowwhenit isintheoffstate. ThedifferencesbetweenCOSUC384xfamily memberaretheunder-voltagelockout thresholdsandthemaximumdutycycle ranges. ModelUVLO ThresholdMax.Duty Cycle COSUC384216V(Von) 10V(Voff)100% COSUC38438.4V(Von) 7.6V(Voff)100% COSUC384416V(Von) 10V(Voff)50% COSUC38458.4V(Von) 7.6V(Voff)50%Current-ModePWMControllers COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 21.PinConfigurationandBlockDiagram Figure1.PinDiagram Table1.PinDescription Pin Name I/O Description 1COMP OOutputoftheerroramplifierforcompensation.Connectexternal compensationcomponentstothispintomodifytheerroramplifieroutput. Theerroramplifierisinternallycurrentlimitedsotheuserscancommand zerodutycyclebyexternallyforcingCOMPtoGROUND. 2VFB IInvertinginputtotheerroramplifier.Itisnormallyconnectedtothe switchingpowersupplyoutputthrougharesistordivider. 3ISENSE IAvoltageproportionaltoinductorcurrentisconnectedtothisinput.The PWMuseshisinformationtoterminatetheoutputswitchconduction.A voltagerampcanbeappliedtothispintorunthedevicewitha voltage-modecontrolconfiguration. 4RT/CT I/OTheoscillatorfrequencyandmaximumoutputdutycycleare programmedbyconnectingresistorRTtoVREFandcapacitorCTto ground.Operationupto1MHzispossible. 5GROUND PGroundreturnpin.Itfunctionsasbothpowergroundandanalogground. 6OUTPUT OOutputoftheon-chipdrivestage.Itdirectlydrivesthegateofapower MOSFET.Peakcurrentupto1Aaresourcedandsunkbythispin. OutputisactivelyheldlowwhenVCCisbelowtheturnonthreshold. 7VCC PPowersupplypinforthecontrolIC.Thispinshouldbebypassedwitha 0.1-µFceramiclowESLcapacitorwithminimaltracelengths.An additionalbypasscapacitoratleast10timesgreaterthanthegate capacitanceofthemainswitchingMOSFETusedinthedesignisalso requiredonVCC. 8VREF O5Vreference.ItprovideschargingcurrentforcapacitorCTthrough resistorRT.Forstability,thereferenceshouldbebypassedwitha0.1-µF ceramiclowESLcapacitorandminimaltracelengthtothegroundplane. COSUC3842,3843,3844,3845 www.cosine-ic.com 3 Figure2.COSUC3842and3843BlockDiagram (Note:withdutycyclesapproaching100%) Figure3.COSUC3844and3845BlockDiagram (Note:withdutycyclesapproaching50%) COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 42.OrderingInformation Model OrderNumberPackagePackageOptionMarkingInformation COSUC3842SOP- UC3842BD 8 TapeandReel,3000 COS3842BD DIP- UC3842BN 8 Tube,50 COS3842BN COSUC3843COSUC3843BD SOP-8 TapeandReel,3000 COS3843BD COSUC3843BN DIP-8 Tube,50 COS3843BN COSUC3844COSUC3844BD SOP-8 TapeandReel,3000 COS3844BD COSUC3844BN DIP-8 Tube,50 COS3844BN COSUC3845COSUC3845BD SOP-8 TapeandReel,3000 COS3845BD COSUC3845BN DIP-8 Tube,50 COS3845BN 3.ProductSpecification 3.1AbsoluteMaximumRatings(1) Parameter Sym. Min Max Unit SupplyVoltage VCC 30 V AnalogInputs VFB,ISENSE -0.3 6 V OutputCurrent,SourceorSink IO ±1 A ErrorAmplifierOutputSinkCurrent ICOMP 10 mA OperatingJunctionTemperature TJ -40 +125 °C StorageTemperature TS -55 +150 °C LeadTemperature(soldering10s) TL +300 °C (1)Stressesexceedingtheabsolutemaximumratingsmaydamagethedevice.Thedevicemaynotfunctionorbeoperable abovetherecommendedoperatingconditionsandstressingthepartstotheselevelsisnotrecommended.Inaddition, extendedexposuretostressesabovetherecommendedoperatingconditionsmayaffectdevicereliability.Theabsolute maximumratingsarestressratingsonly. 3.2ThermalData Parameter Rating Unit PackageThermalResistance,RθJA (Juntion-to-ambient)150(SOP8) 90(DIP8)°C/W COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 53.3RecommendedOperatingConditions Parameter Min. Typ. Max. Unit VccSupplyVoltage - - 30 V VFBInputVoltage - - 2.5 V ISENSEInputVoltage - - 1 V Sink/SourceLoadCurrent(average) - 200 mA ReferenceLoadCurrent 0 - 20 mA OscillatorFrequencyRange - 100 500 kHz OperatingJunctionTemperature -40 - +125 °C 3.4ElectricalCharacteristics (TypicalvaluesaretestedatVCC=20V,TA=25oC,unlessotherwisespecified.) Parameter Sym. Conditions Min.Typ.Max.Unit POWERSUPPLY SupplyVoltage VCC 7.6 - 30 V OperatingSupplyCurrent ISVFB=VISENSE=0V - 12 17 mA Start-upCurrent 0.1 0.3 mA REFERENCE OutputVoltage VREF 4.95 5.0 5.05 V LineRegulation ΔVREFVIN=8Vto30V - 10 20 mV LoadRegulation ΔVREFIL=0to20mA - 20 50 mV Temp.Stability ΔVREFOveroperatingrange 20 50 mV TotalOutputVariation VREFLine,Load,andTemperature4.9 - 5.1 V ShortCircuitOutputCurrent ISCVREF=0 30 100 180mA OSCILLATOR Frequency fOSCRT=10kΩ,CT=3.3μF 47 52 57 kHz VoltageStability Δf/ΔVINVIN=12Vto25V - 0.2 1 % TemperatureStability Δf/ΔTVIN=12Vto25V - 5 - % COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 6ClockAmplitude VRT/CT - 1.6 - V ERRORAMPLIFIER InputVoltage VFB 2.42 2.5 2.58 V InputBiasCurrent IB - 0.1 2 μA OpenLoopVoltageGain GVOL2≤VCOMP≤4V 65 90 - dB Gain-BandwidthProduct GBPAV=0dB 0.7 1 - MHz PowerSupplyRejectionRatioPSRR1VIN=12Vto25V 60 70 - dB COMPSinkCurrent ISKVFB=2.7V,VCOMP=1.1V 2 12 - mA COMPSourceCurrent ISRCVFB=2.3V,VCOMP=5V -0.5 -1 - mA Low-levelOutputVoltage VOLVFB=2.7V; RL=15-kΩCOMPtoVREF0.8 1.1 V High-levelOutputVoltage VOHVFB=2.3V; RL=15-kΩCOMPtoGround5 6.2 V PWMCOMPARATOR Gain GCOMPG=ΔVCOMP/ΔVISENSE, 0V≤VISENSE≤0.8V2.85 3 3.15V/V MaxmumInputSignal VISENSE 0.9 1 1.1 V InputBiasCurrent IISENSE - -2 -10 μA PowerSupplyRejectionRatioPSRR2VCC=12Vto25V - 70 - dB DelaytoOutput tDLYVISENSEsteppedfrom0to2V 150 300 ns OUTPUTDRIVER Low-levelOutputVoltageVOLIISINK=20mA - 0.2 0.4 V VOLIIISINK=200mA - 1.6 2.2 V High-levelOutputVoltageVOHIISOURCE=20mA 18 19 - V VOHIIISOURCE=200mA 17 18 - V RiseTime tRCL=1nF - 50 150 ns FallTime tFCL=1nF - 50 150 ns COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 7UNDER-VOLTAGELOCKOUT(UVLO) UVLOEnableThreshold UVLONCOS3842/3844 14.5 16 17.5 V COS3843/3845 7.8 8.4 9.0 V UVLOOffThreshold UVLOFFCOS3842/3844 8.5 10 11.5 V COS3843/3845 7.0 7.6 8.2 V PWMDUTYCYCLE MaximumDutyCycle DMAXCOS3842/3843 94 96 100 % COS3844/3845 47 48 50 % MinimumDutyCycle DMIN 0 % 4.ApplicationInformation 4.0Overview TheCOSUC384xseriesofpulsewidthmodulator(PWM)integratedcircuitsprovidethefeatures necessarytoimplementAC-DCorDC-to-DCfixed-frequencycurrentmodecontrolschemeswitha minimumnumberofexternalcomponents.Protectioncircuitryincludesundervoltagelockout(UVLO) andcurrentlimiting.Internallyimplementedcircuitsincludeastart-upcurrentoflessthan1mA,a precisionreferencetrimmedforaccuracyattheerroramplifierinput,logictoensurelatched operation,apulse-widthmodulation(PWM)comparatorthatalsoprovidescurrent-limitcontrol,anda totem-poleoutputstagedesignedtosourceandsinkhigh-peakcurrent.Theoutputstage,suitable fordrivingN-channelMOSFETs,islowwhenitisintheoff-state. ThedifferencesbetweenmembersofCOSUC384xseriesaretheUVLOthresholdsandmaximum duty-cycleasshowninTable2. Table2.DeviceInformation Model UVLOThreshold Max.DutyCycle COSUC384216V(Von) 10V(Voff)100% COSUC38438.4V(Von) 7.6V(Voff)100% COSUC384416V(Von) 10V(Voff)50% COSUC38458.4V(Von) 7.6V(Voff)50% COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 8TypicalUVLOthresholdsof16V(ON)and10V(OFF)ontheCOSUC3842and3844devicesmake themideallysuitedtooff-lineAC-DCapplications.ThecorrespondingtypicalthresholdsfortheCOS UC3843and3845devicesare8.4V(ON)and7.6V(OFF),makingthemidealforusewithregulated inputvoltagesusedinDC-DCapplications.TheCOSUC3842and3843devicesoperateatduty cyclesapproaching100%.TheCOSUC3844and3845haveaduty-cyclerangeof0%to50%bythe additionofaninternaltoggleflip-flop,whichblankstheoutputoffeveryotherclockcycle. TheCOSUC384xusesanexternalresistortosetthechargingcurrentfortheexternalcapacitor, whichdeterminestheoscillatorfrequencyasfollowingequation: fOSC=1.72/(RRT×CCT) (1) Therecommendedrangeoftimingresistorvaluesisbetween5kΩand100kΩ;therecommended rangeoftimingcapacitorvaluesisbetween1nFand100nF. 4.1Open-LoopTestFixture Anopen-looplaboratorytestfixture(Figure4)isusedtodemonstratethesetupanduseoftheCOS UC3842devicesandtheirinternalcircuitry.Thetransistorand5-kΩpotentiometersamplethe oscillatorwaveformandapplyanadjustableramptotheISENSEterminals.Highpeakcurrents associatedwithcapacitiveloadsnecessitatecarefulgroundingtechniques.Timingandbypass capacitorsshouldbeconnectedclosetopin5inasinglepointground. Figure4.Open-LoopLaboratoryTestFixture COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 94.2TypicalApplication AtypicalapplicationfortheCOSUC3842inanoff-lineflybackconverterisshowninFigure5.Itis capableofproviding48Wat12VoutputvoltagefromauniversalACinput.Thedesignusespeak primarycurrentcontrolinacontinuouscurrentmodePWMconverter. Figure5.AnOff-LineFlybackConverterScheme COS UC3842, 3843, 3844, 3845 www.cosine-ic.com 105.PackageInformation 5.1SOP8(PackageOutlineDimensions) 5.2DIP8(PackageOutlineDimensions)