MP2403互換的同步降壓型DCDC穩(wěn)壓器MXT2485

1、MXT248536V,3A,250KHzSynchronousStep-DownDC/DCConverterGeneralDescriptionTheMXT2485isasynchronousstep-downDC/DCconverterthatprovideswide4.6Vto36Vinputvoltagerangeand3Acontinuousloadcurrentcapability.Faultprotectionineludescycle-by-cyclecurrentlimit,inputUVLO,outputovervoltageprotectionandthermalshutd

2、own.Besides,adjustablesoft-startfunctionpreventsinrushcurrentatturn-on.Thisdeviceusescurrentmodecontrolschemethatprovidesfasttransientresponse.Inshutdownmode,thesupplycurrentislessthan1uA.TheMXT2485isavailableinanSOP8-EPpackage,providesaverycompactsystemsolutionandgoodthermalconductanee.PinConfigura

3、tionTopViewFeaturesWideInputVoltagefrom4.6Vto36V3AOutputCurrentAdjustableOutputVoltagefrom0.8Vto28VHighEfficiencyUpto95%Fb(ed250KHzSwitchingFrequencyCurrentModeOperationAdjustableSoft-StartCycle-by-CyclecurrentlimitInputUnderVoltageLockoutOver-TemperatureProtectionThermalEnhancedSOP-8PackageRoHSComp

4、liantApplicationSet-Top-BoxDVD,LCDDisplaysDistributedPowerSystemDatacom,XDSLPre-RegulatorforLinearRegulatorsBS1|8SSvinn-I7ENSW|3I!6|COMPGND4IGND；5|FBExposedPadOrderingInformationPartNumberPackageShipmentMXT2485ADJSBCRSOP8-EPTape&Reel/3000*SB:SOP8-EPC:Green,-4085CR；Tape&ReelMXT2485 TypicalApphcationC

5、ircuitOFFIC丄0.1uFjVINBSENSWSSFBGNDCOMP27584,ExposedpadZLcs3nFLiUB340(optional)c?(optional)VqutMXT2485 #MXT2485 C6(optional)Figure1TypicalApplicationCircuitVoutRir2r3c3LiC25.0V53.5K10K7.5K3.3nF10-15UH22uFx2Ceramic3.3V31.25K10K5.6K3.3nF6.8-10uH22uFx2Ceramic2.5V21.5K10K4.7K3.3nF4.7-6.8uH47uFCeramic1.8V

6、12.5K10K3.3K3.3nF4.7uH47uFx2CeramicPinFunctionDescriptionPinNO.PinNamePinDescription1BSHighSideGateDriveBoostInput.A10nForgreatercapacitormustbeconnectedfromthispintoSW.ItcanboostthegatedrivetofullytunontheintemalhighsideNMOS.2VINPowerSupplyInputPin.Drive4.6Vto36Vvoltagetothispintopoweronthischip.Co

7、nnectinga10uFceramicbypasscapacitorbetweenVINandGNDtoeliminatenoise.3SWPowerSwitchingOutput.ItistheoutputpinthatinternalhighsideNMOSswitchingtosupplypower.4/EPGNDGroundPin.Connect!ngEP(exposedpad)toPin4.5FBVoltageFeedbackInputPin.ConnectingFBandVOUTwitharesistivevoltagedivider.ThisICsensesfeedbackvo

8、ltageviaFBandregulateitat0.8V.6COMPCompensationPin.Thispinisusedtocompensatetheregulationcontrolloop.ConnectaseriesRCnetworkfromCOMPpintoGND.7ENEnableInputPin.Thispinprovidesadigitalcontroltotuntheconverteronooff.ConnecttoVINwitha100KQresistorforself-startup.8SSSoft-StartInputPin.Thispincontrolsthes

9、oft-startperiod.ConnectacapacitorfromSStoGNDtosetthesoftstartperiod.AbsoluteMaximumRatingsInputSupplyVoltageV,N0.3V+39VENVoltageVEN03V+39VSWVoltageVsw(V)N+0.3V)MXT2485 BoostVoltageVBS(Vsw-0.3V)(Vsw+6V).TOC o 1-5 h zAllOtherPinsVoltage-0.3V6VMaximumJunctionTemperature150CStorageTemperature-65C150CLea

10、dTemperature(Soldering10sec)260CClass2ESDClassification(HBM)RecommendedOperatingConditionsInputSupplyVoltageV,N4.6V36VOutputVoltageV0UT0.8V28VAmbientTemperatureTA40C85CThermalCharacteristicsSOP-8(ExposedPad),eJA75C/WSOP-8(ExposedPad),6JC15C/WNotes:Stressesexceedthoseratingsmaydamagethedevice.Ifoutof

11、itsoperationconditions,thedeviceisnotguaranteedtofunction.ElectricalCharacteristic(V|N=12V,Ta=25C,unlessotherwisespecified)ParameterSymbolTestConditionsMinMaxUnitV|NInputSupplyVoltage(34.636VV|NSupplyCurrentVEN=VlN,VFB=1.0V1.1mAV)NShutdownSupplyCurrentVEN二ov0.33maFeedbackVoltageVfb4-6VSMnW36V0.780.8

12、00.82V-40CSTaW85C0.7650.835FeedbackOVPThresholdVoltage0.90.951VHigh-SideMOSFETRDS(ON)(4)150mQLow-SideMOSFETRDS(ON)(4)80mQHigh-SideMOSFETLeakageCurrentVEN二0V,Vsw=0V10uAHigh-SideMOSFETCurrentLimit(4)45ALow-SideMOSFETCurrentLimitFromdraintosource1.5ACOMPtoCurrentsenseTansconductoneeGes7A/VElectricalCha

13、racteristic(continued)(V|N=12V,Ta=25C,unlessotherwisespecified)ErrorAmplifierTransconductanceGeaIcomp=10pA820pA/VErrorAmplifierVoltageGainAea400v/vOscillationfrequencyFosc200250300KHzShortCircuitOscillationFrequencyFoscVFB二ov55KHzMaximumDutyCycleDmaxVfb二0.7V8090%MinimumOnTimeTon180nsInputUVLOThresho

14、ldV|NRising4.34.5VUnderVoltageLockoutThresholdHysteresis200mVSoft-StartCurrentVcomp二0V;Vss二0V6uASoft-StartPeriodCss二0.1uF15msENShutdownThresholdVoltage1.52.0VThermalShutdownThreshold(4)160CNotes:WhenVIN=4.6VV0UT=3.3Vonlyload1.2A.(4)Guaranteedbydesign.FunctionalBlockDiagramMXT2485 MXT2485 TypicalOper

15、atingCharacteristicsC1=10uF5C2=22uFx2,L1=10uH,C4=NA,Ta=+25C9unlessotherwisenoted.EfficiencyTestVout=3.3VSteadyStateVinh2V,Vout=3.3VJout=OATrigdMPcs:0.000$VOUtswILJUUX1OCH12O.DmVCH21Q0VEUM2.50小CH42.0OA11-Nov-ll10:49SteadyStateVin=12V,Vout=3.3V,lout=3.0ATrigdMPcs:0.000$MEASIRECH1Pk-Rc20.0mVCH2Freq267.

16、1kHz?CH4Max560nrtCH4Mean-51.1mACH4Min-640mACH2Z4.40V267.175kHzDynamicloadingVin=12V,Vout=3.3VJout=1.5to3.0AVoutSWILVoutENloutzjmuiJuLrLJjMEASIRECH1Pk-Rc20.0mVCH2Freq2曲4kHz?CH4Max3.52AVoutCH4Mean28取CH4Min2.32ACH12O.DmVBjCH21Q0VEUM2.50小CH2Z4.WCH42OOA旳11-Nov-ll10:43266.22kHzPowerOnVin=12V,Vout=3.3V,lou

17、t=3.0ACH41.00A11-Nov-ll12:91MEASIRECH1Pk-Rc360mVCH2FreqCH4Max3.08ACH4Mean22”CH4Min1.32ACH1200mVCbM1.00AM10(11$11-Nov-ll10:4?CH4Z1.92A1.00000kHzShutDownVin=12V,Vout=3.3V,lout=0.05ATekJkmPo$：o.ooo$MEASIRECH1Pk-Rc3.44VCH2Freq?CH4MaxES.OrrACH4Mean2.3rrACH4Min-16.0mACH120叫珈C也5.0OVBJM2.50m$CH4KOmAE11-Nov-

18、ll11:M20V).Itcanimprovethedevicesstability.TheoutputripplevoltageVqutisdescribedas:AX/Vout(.Vout)1)fs丄(Vin丿I8fsC2丿Wherefsistheswitchingfrequency,Listheinductaneevalue,V,Nistheinputvoltage,V0Utistheoutputvoltage,Resristheequivalentseriesresistaneevalueoftheoutputcapacitor,andtheC2istheoutputcapacitor

19、.Whenusingtheceramiccapacitors,theRsrcanbeignoredandtheoutputripplevoltageAV0Utisshownas:AVOUT=yUT8LC2IViN)Whenusingtantalumorelectrolyticcapacitors,typically90%oftheoutputvoltagerippleiscontributedbytheESRofoutputcapacitors.theoutputripplevoltageAVoutcanbeestimatedas:.#Vout(.Vout)_aVout=1-ResrfsLIV

20、in)ThecharacteristicsoftheoutputcapacitoralsoaffectthestabilityoftheregulationsystemTheAN6403canbeoptimizedforawiderangeofcapacitaneeandESRvaluesInductorTheoutputinductorisusedforstoreenergyandfilteroutputripplecurrent.AlargevalueinductorwillresultinlessripplecurrentandloweroutputMXT2485 ripplevolta

21、geButthetrade-offconditionoftenhappensbetweenmaximumenergystorageandthephysicalsizeoftheinductor.Thefirstconsiderationforselectingtheoutputinductoristomakesurethattheinductanceislargeenoughtokeeptheconverierinthecontinuouscurrentmode.ThatwilllowerripplecurrentandresultsinloweroutputripplevoltageAgoodrulefordeterminingtheinductaneeissetthepeak-to-peakinductorripplecurrentAlalmostequalto30%ofthemaximumloadcurrent