至18v输入、5.5a同步降压转换器

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ZHCS920–MAYD-CAP2™模式支持快速瞬态响 TPS54525是一款自适应接通时间D-CAP2™模式宽泛的输入电压范围：4.5V18输出电压范围：0.76V

步降压转换器。TPS54525可帮助系统设计人员通过终端设备的电源总线调节器集。TPS54525的主控制环路使用D-CAP2™模式控制，此控制方式提供一个 无需外部补偿组件的极快速瞬态响应。TPS54525-63mΩ（高侧）与33mΩ（低侧 专有电路还有助于该器件适应诸如POSCAP或 CAP等效串联电阻(ESR)输出电容器以及超 ESR陶瓷电容器。该器件的工作输入电压VIN介 4.8V至18V之间。输出电压可在0.76V与5.5 650kHz开关频率 个电源正常功能。TPS54525采用14引脚散热薄 小外形尺寸(HTSSOP)封装，设计工作温度介于 Blu-rayDisc™器

40°C85°CPleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddierstheretoappearsattheendofthisdatasheet.Copyright©2012,TexasInstrumentsD-CAP2,PowerPADCopyright©2012,TexasInstrumentsPRODUCTIONDATAinformationiscurrentasofpublicationdate.ProductsconformtospecificationsperthetermsoftheInstrumentsstandardwarranty.Productionprocessingdoes EnglishDataSheet:necessarilyincludetestingofallThisintegratedcircuitcanbedamagedbyESD.TexasInstruments mendsthatallintegratedcircuitsbehandledwithappropriateprecautions.Failuretoobserveproperhandlingandinstallationprocedurescancausedamage.ESDdamagecanrangefromsubtleperformancedegradationtocompletedevicefailure.Precisionintegratedcircuitsmaybemoresusceptibletodamagebecauseverysmallparametricchangescouldcausethedevicenottomeetitspublishedspecifications.ORDERINGPACKAGE(2)ORDERABLEPARTMEDIA,TY–45°CtoTapeandForthemostcurrentpackageandorderinginformation,seethePackageOptionAddendumattheendofthis,orseetheTIwebsiteatPackagedrawings,thermaldata,andsymbolizationareavailable AllpackageoptionshaveCuNIPDAUlead/ballABSOLUTEUMover -airtemperaturerange(unlessotherwisenoted)InputvoltageVIN1,VIN2–0.3toV–0.3toVVBST(10ns–0.3toVVBST(vsSW1,–0.3toVVFB,VO,SS,–0.3toVSW1,–2toVSW1,SW2(10ns–3toVOutputvoltage–0.3toVPGND1,–0.3toVVoltagefromGNDto–0.2toVESDHumanBodyModel2ChargedDeviceModelVOperatingjunction–40toStorage–55toStressesbeyondthoselistedunderabsoluteumratingsmaycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunder mendedoperatingconditionsisnotimplied.Exposuretoabsolute- um-ratedconditionsforextendedperiodsmayaffectdevicereliability.THERMALTHERMAL14Junction-to-ambientJunction-to-case(top)thermalJunction-to-case(bottom)thermal有关传统和全新热度量的信息，请参阅IC封装热度量应用报告（文献号：SPRA953）MENDEDOPERATINGoveroperating-airtemperaturerange(unlessotherwiseSupplyinputvoltageVInputvoltageVVBST(10nsVBST(vsSW1,-SS,VO,SW1,SW1,SW2(10nsPGND1,OutputvoltageVOutputCurrent05-airOperatingjunctionELECTRICALoveroperating-airtemperaturerange,VIN=12V(unlessotherwiseTESTSUPPLYOperating-non-switchingsupplyVINcurrent,TA=25°C,EN=5V,VVFB=0.8VShutdownsupplyVINcurrent,TA=25°C,EN=0LOGICENhigh-levelinputVENlow-levelinputVENtoVEN=12VFBVOLTAGEANDDISCHARGEVFBthresholdTA=25°C,VO=1.05V,continuousTA=0°Cto85°C,VO=1.05V,continuousTA=–40°Cto85°C,VO=1.05V,continuousVFBinputVVFB=0.8V,TA=0VOVEN=0V,VO=0.5V,TA=ΩVREG5VREG5outputTA=25°C,6.0V<VIN<18V,0<IVREG5<5mAVVREG5Line6.0V<VIN<18V,IVREG5=5VREG5Load0mA<IVREG5<5VREG5OutputVIN=6V,VVREG5=4V,TA=HighsideswitchTA=25°C,VBST-VSW1,2=5.5LowsideswitchTA=NotproductionELECTRICALCHARACTERISTICS(overoperating-airtemperaturerange,VIN=12V(unlessotherwiseTESTCURRENTCurrentLOUT=1.5ATHERMALThermalshutdownShutdowntemperatureHysteresisON-TIMETIMEROnVIN=12V,VO=1.05MinimumoffTA=25°C,VVFB=0.7SOFTSSchargeVSS=1SSdischargeVSS=0.5POWERPGVVFBrising%VVFBfalling%PGsinkVPG=0.5 OUTPUTUNDERVOLTAGEANDOVERVOLTAGEOutputOVPtripOVP%OutputOVPpropOutputUVPtripUVP%%OutputUVPOutputUVPenableRelativetosoft-startxUVLOWakeupVREG5VFallVREG5HysteresisVREG5NotproductionDEVICE(TOPVIEW)11VIN13VREG5POWER VBSTSW1PGND2PGND1PIN1Connecttooutputofconverter.Thispinisusedforoutputdischarge2Converterfeedbackinput.Connecttooutputvoltagewithfeedbackresistor35.5Vpowersupplyoutput.Acapacitor(typical1µF)shouldbeconnectedtoGND.VREG5isnotactivewhenENislow.4Soft-startcontrol.Anexternalcapacitorshouldbeconnectedto5Signalground6Opendrainpowergood7Enablecontrolinput.ENisactivehighandmustbepulleduptoenablethePGND1,8,Groundreturnsforlow-sideMOSFET.Alsoserveasinputsofcurrentcomparators.ConnectPGNDandGNDstronglytogetherneartheIC.SW1,10,Switchnodeconnectionbetweenhigh-sideNFETandlow-sideNFET.AlsoserveasinputstocurrentSupplyinputforhigh-sideNFETgatedriver(boostterminal).ConnectcapacitorfromthispintorespectiveSW1,SW2terminals.AninternalPNdiodeisconnectedbetweenVREG5toVBSTpin.VIN1,13,PowerinputandconnectedtohighsideNFETdrain.Supplyinputfor5-Vinternallinearregulatorforthecontrolcircuitry.BackThermalpadofthepackage.Mustbesolderedtoachieveappropriatedissipation.ShouldbeconnectedtoPGND.FUNCTIONALBLOCKSGNDTheTPS54525isa5.5-Asynchronousstep-down(buck)converterwithtwointegratedN-channelMOSFETs.ItoperatesusingD-CAP2™modecontrol.ThefasttransientresponseofD-CAP2™controlreducestheoutputcapacitancerequiredtomeetaspecificlevelofperformance.ProprietaryinternalcircuitryallowstheuseoflowESRoutputcapacitorsincludingceramicandspecialpolymertypes.DETAILEDOperationThemaincontrolloopoftheTPS54525isanadaptiveon-timepulsewidthmodulation()controllerthatsupportsaproprietaryD-CAP2™modecontrol.D-CAP2™modecontrolcombinesconstanton-timecontrolwithaninternalcompensationcircuitforpseudo-fixedfrequencyandlowexternalcomponentcountconfigurationwithbothlowESRandceramicoutputcapacitors.Itisstableevenwithvirtuallynorippleattheoutput.Atthebeginningofeachcycle,thehigh-sideMOSFETisturnedon.ThisMOSFETisturnedoffafterinternaloneshottimerexpires.Thisoneshotissetbytheconverterinputvoltage,VIN,andtheoutputvoltage,VO,tomaintainapseudo-fixedfrequencyovertheinputvoltagerange,henceitiscalledadaptiveon-timecontrol.Theone-shottimerisresetandthehigh-sideMOSFETisturnedonagainwhenthefeedbackvoltagefallsbelowthereferencevoltage.Aninternalrampisaddedtoreferencevoltagetosimulateoutputripple,eliminatingtheneedforESRinducedoutputripplefromD-CAP2™modecontrol.FrequencyandAdaptiveOn-TimeTPS54525usesanadaptiveon-timecontrolschemeanddoesnothaveadedicatedonboardoscillator.TheTPS54525runswithapseudo-constantfrequencyof650kHzbyusingtheinputvoltageandoutputvoltagetosettheon-timeone-shottimer.Theon-timeisinverselyproportionaltotheinputvoltageandproportionaltotheoutputvoltage,therefore,whenthedutyratioisVOUT/VIN,thefrequencyisconstant.SoftStartandPre-BiasedSoftThesoftstartfunctionisadjustable.WhentheENpin eshigh,6-μAcurrentbeginschargingthecapacitorwhichisconnectedfromtheSSpintoGND.Smoothcontroloftheoutputvoltageismaintainedduringstartup.TheequationfortheslowstarttimeisshowninEquation1.VFBvoltageis0.765VandSSpinsourcecurrentis6μA.C(nF)xV1.1C(nF)xtSS(ms) SS

SS

TheTPS54525containsauniquecircuittopreventcurrentfrombeingpulledfromtheoutputduringstartupiftheoutputispre-biased.Whenthesoft-startcommandsavoltagehigherthanthepre-biaslevel(internalsoftstartesgreaterthanfeedbackvoltageVFB),thecontrollerslowlyactivatessynchronousrectificationbystartingthefirstlowsideFETgatedriverpulseswithanarrowon-time.Itthenincrementsthaton-timeonacycle-by-cyclebasisuntilitcoincideswiththetimedictatedby(1-D),whereDisthedutycycleoftheconverter.Thisschemepreventstheinitialsinkingofthepre-biasoutput,andensurethattheoutvoltage(VO)startsandrampsupsmoothlyintoregulationandthecontrolloopisgiventimetotransitionfrompre-biasedstart-uptonormalmodeoperation.PowerTheTPS54525haspower-goodopendrainoutput.Thepowergoodfunctionisactivatedaftersoftstarthasfinished.Thepowergoodfunction esactiveafter1.7timessoft-starttime.Whentheoutputvoltageiswithin-10%ofthetargetvalue,internalcomparatorsdetectpowergoodstateandthepowergoodsignal eshigh.Rpgresistervalue,whichisconnectedbetweenPGandVREG5,isrequiredfrom25kΩto150kΩ.Ifthefeedbackvoltagegoesunder15%ofthetargetvalue,thepowergoodsignal eslow.VREG5isaninternallygeneratedvoltagesourceusedbytheTPS54525.Itisderiveddirectlyfromtheinputvoltageandisnominallyregulatedto5.5Vwhentheinputvoltageisabove5.6V.TheoutputoftheVREG5regulatoristheinputtotheinternalUVLOfunction.VREG5mustbeabovetheUVLOwakeupthresholdvoltage(3.6Vtypical)fortheTPS54525tofunction.Connecta1.0µFcapacitorbetweenpin3oftheTPS54525andpowergroundforproperregulationoftheVREG5output.TheVREG5outputvoltageisavailableforexternaluse.Itis mendedtousenomorethan5mAforexternalloads.TheVREG5outputisdisabledwhentheTPS54525ENpinisopenorpulledlow.OutputDischargeTPS54525dischargestheoutputwhenENislow,orthecontrolleristurnedoffbytheprotectionfunctions(OVP,UVP,UVLOandthermalshutdown).Theoutputisdischargedbyaninternal50-ΩMOSFETwhichisconnectedfromVOtoPGND.Theinternallow-sideMOSFETisnotturnedonduringtheoutputdischargeoperationtoavoidthepossibilityofcausingnegativevoltageattheoutput.CurrentTheoutputovercurrentprotection(OCP)isimplementedusingacycle-by-cyclevalleydetectcontrolcircuit.Theswitchcurrentismonitoredbymeasuringthelow-sideFETswitchvoltagebetweentheSWpinandGND.Thisvoltageisproportionaltotheswitchcurrent.Toimproveaccuracy,thevoltagesensingistemperatureDuringtheontimeofthehigh-sideFETswitch,theswitchcurrentincreasesatalinearratedeterminedbyVIN,VOUT,theon-timeandtheoutputinductorvalue.Duringtheontimeofthelow-sideFETswitch,thiscurrentdecreaseslinearly.TheaveragevalueoftheswitchcurrentistheloadcurrentIOUT.Ifthemeasuredvoltageisabovethevoltageproportionaltothecurrentlimit,Then,thedeviceconstantlymonitorsthelow-sideFETswitchvoltage,whichisproportionaltotheswitchcurrent,duringthelow-sideon-time.Theconvertermaintainsthelow-sideswitchonuntilthemeasuredvoltageisbelowthevoltagecorrespondingtothecurrentlimitatwhichtimetheswitchingcycleisterminatedandanewswitchingcyclebegins.Insubsequentswitchingcycles,theon-timeissettoafixedvalueandthecurrentismonitoredinthesamemanner.Therearesomeimportantconsiderationsforthistypeofovercurrentprotection.Theloadcurrentonehalfofthepeak-to-peakinductorcurrenthigherthantheovercurrentthreshold.Alsowhenthecurrentisbeinglimited,theoutputvoltagetendstofallasthedemandedloadcurrentmaybehigherthanthecurrentavailablefromtheconverter.Thismaycausetheoutputundervoltageprotectioncircuittobeactivated.Whentheovercurrentconditionisremoved,theoutputvoltagereturnstotheregulatedvalue.Thisprotectionisnon-latching.Over/UnderVoltageTPS54525monitorsaresistordividedfeedbackvoltagetodetectoverandundervoltage.Whenthefeedback eshigherthan125%ofthetargetvoltage,theOVPcomparatoroutputgoeshighandthecircuitlatchesasthehigh-sideMOSFETdriverturnsoffandthelow-sideMOSFETturnson.Whenthefeedback eslowerthan65%ofthetargetvoltage,theUVPcomparatoroutputgoeshighandaninternalUVPdelaycounterbegins.After250μs,thedevicelatchesoffbothinternaltopandbottomMOSFET.Thisfunctionisenabledapproximay1.7xsoftstarttime.UVLOUndervoltagelockoutprotection(UVLO)monitorsthevoltageoftheVREG5pin.WhentheVREG5voltageislowerthanUVLOthresholdvoltage,theTPS54525isshutoff.Thisisprotectionisnon-latching.ThermalTPS54525monitorsthetemperatureofitself.Ifthetemperatureexceedsthethresholdvalue(typically165°C),thedeviceisshutoff.Thisisnon-latchprotection.TYPICALTYPICALVIN=12V,TA=25°C(unlessotherwise

VIN VINSHUTDOWN JUNCTION JUNCTIONSupplyCurrent−ShutdownSupplyCurrent−ShutdownCurrentSupplyCurrentSupplyCurrent 0 JunctionTemperature

0 JunctionTemperatureFigure FigureEN 1.05-VOUTPUT EN OUTPUT ENInputENInputCurrentOutputVoltage 50 ENInputVoltage

OutputCurrentFigure FigureOutputOutputVoltage

1.05-VOUTPUT 1.05-V,50-mAto5.5-AINPUT TRANSIENT InputVoltageFigure FigureSTART-UPWAVE OUTPUTEfficiencyEfficiency00.00.51.01.52.02.53.03.54.04.55.0OutputCurrentFigure Figure

SWITCHING SWITCHING INPUTVOLTAGE(IO=1 OUTPUT SwitchingFrequencySwitchingFrequencySwitchingFrequency 05Input05InputVoltage01 OutputCurrent45Figure FigureVOLTAGERIPPLEATOUTPUT(IO=5.5 VOLTAGERIPPLEATINPUT(IO=5.5VOVO=1.05VO(10mV/divacSW(5VO=1.05VIN(50mV/divacSW(5Figure FigureOUTPUTAMBIENT65OutputOutputCurrent3210 AmbientTemperatureFigure

DESIGNStepByStepDesignTobeginthedesignprocess,youmustknowafewapplicationInputvoltageOutputOutputOutputvoltageInputvoltageFigure14.ShowstheschematicdiagramforthisdesignOutputVoltageResistorsTheoutputvoltageissetwitharesistordividerfromtheoutputnodetotheVFBpin.Itis mendedtouse1%toleranceorbetterdividerresistors.StartbyusingEquation2tocalculateVOUT.1+ 1+

=0.765 OutputFilterTheoutputfilterusedwiththeTPS54525isanLCcircuit.ThisLCfilterhasdoublepole1FP

Atlowfrequencies,theoverallloopgainissetbytheoutputset-pointresistordividernetworkandtheinternalgainoftheTPS54525.Thelowfrequencyphaseis180degrees.Attheoutputfilterpolefrequency,thegainrollsoffata-40dBperdecaderateandthephasedropsrapidly.D-CAP2™introducesahighfrequencyzerothatreducesthegainrolloffto-20dBperdecadeandincreasesthephaseto90degreesonedecadeabovethezerofrequency.TheinductorandcapacitorselectedfortheoutputfiltermustbeselectedsothatthedoublepoleofEquation3islocatedbelowthehighfrequencyzerobutcloseenoughthatthephaseboostprovidedbethehighfrequencyzeroprovidesadequatephasemarginforastablecircuit.TomeetthisrequirementusethemendedinTableTable mendedComponentOutputVoltageR1R2C4L1C8+C911.0-22-1.0-22-1.0-22-22-5-22-5-22-5-22-55-22-(1)Forhigheroutputvoltagesatorabove1.8V,additionalphaseboostcanbeachievedbyaddingafeedforwardcapacitor(C4)inparallelwithR1.SincetheDCgainisdependentontheoutputvoltage,therequiredinductorvaluewillincreaseastheoutputvoltageincreases.Forhigheroutputvoltagesatorabove1.8V,additionalphaseboostcanbeachievedbyaddingafeedforwardcapacitor(C4)inparallelwithR1Theinductorpeak-to-peakripplecurrent,peakcurrentandRMScurrentarecalculatedusingEquation4,Equation5andEquation6.TheinductorsaturationcurrentratingmustbegreaterthanthecalculatedpeakcurrentandtheRMSorheatingcurrentratingmustbegreaterthanthecalculatedRMScurrent.Use650kHzforfSW.Use650kHzforfSW.MakesurethechoseninductorisratedforthepeakcurrentofEquation5andtheRMScurrentofEquation6.Ilp-p=IN

VIN(max)-LO Ilpeak=IO

Ilp-2

Forthisdesignexample,thecalculatedpeakcurrentis6.01AandthecalculatedRMScurrentis5.5A.TheinductorusedisaTDKSPM6530-1R5M100withapeakcurrentratingof11.5AandanRMScurrentratingof11A.ThecapacitorvalueandESRdeterminestheamountofoutputvoltageripple.TheTPS54525isintendedforwithceramicorotherlowESRcapacitors. mendedvaluesrangefrom22uFto68uF.UseEquation7todeterminetherequiredRMScurrentratingfortheoutputcapacitor.CO(RMS) VIN-CO(RMS)12 O

ForthisdesigntwoTDKC3216X5R0J226M22uFoutputcapacitorsareused.ThetypicalESRis2mΩeach.ThecalculatedRMScurrentis0.284Aandeachoutputcapacitorisratedfor4A.InputCapacitorTheTPS54525requiresaninputdecouplingcapacitorandabulkcapacitorisneededdependingontheapplication.Aceramiccapacitorover10μFis mendedforthedecouplingcapacitor.Anadditional0.1µFcapacitorfrompin14togroundis mendedtoimprovetheEMIperformance.Thecapacitorvoltageratingneedstobegreaterthantheuminputvoltage.BootstrapCapacitorA0.1µFceramiccapacitormustbeconnectedbetweentheVBSTtoSWpinforproperoperation.Itismendedtouseaceramiccapacitor.VREG5CapacitorA1.0µFceramiccapacitormustbeconnectedbetweentheVREG5toGNDpinforproperoperation.Itismendedtouseaceramiccapacitor.THERMALThisPowerPad™packageincorporatesanexposedthermalpadthatisdesignedtobedirectlytoanexternalheartsick.Thethermalpadmustbesoldereddirectlytotheprintedboard(PCB).Aftersoldering,thePCBcanbeusedasaheartsick.Inaddition,throughtheuseofthermalvias,thethermalpadcanbeattacheddirectlytotheappropriatecopperneshownintheelectricalschematicforthedevice,oralternatively,canbeattachedtoaspecialheartsickstructuredesignedintothePCB.ThisdesignoptimizestheheattransferfromtheintegratedcircuitForadditionalinformationonthePowerPAD™packageandhowtousetheadvantageofitsheatdissipatingabilities,refertoTechnicalBrief,PowerPAD™ThermallyEnhancedPackage,TexasInstrumentsLitureNo.SLMA002andApplicationBrief,PowerPAD™MadeEasy,TexasInstrumentsLitureNo.SLMA004.Theexposedthermalpaddimensionsforthispackageareshowninthefollowing 1

Thermal7Figure15.ThermalPadLAYOUTKeeptheinputswitchingcurrentloopassmallasKeeptheSWnodeasphysicallysmallandshortaspossibletominimizeparasiticcapacitanceandinductanceandtominimizeradiatedemissions.Kelvinconnectionsshouldbebroughtfromtheoutputtothefeedbackpinofthedevice.Keepogandnon-switchingcomponentsawayfromswitchingMakeasinglepointconnectionfromthesignalgroundtopowerDonotallowswitchingcurrenttoflowundertheVREG5capacitorshouldbecednearthedevice,andconnectedOutputcapacitorshouldbeconnectedtoabroadpatternoftheVoltagefeedbackloopshouldbeasshortaspossible,andpreferablywithgroundLowerresistorofthevoltagedividerwhichisconnectedtotheVFBpinshouldbetiedtoProvidingsufficientviaispreferableforVIN,SWandPGNDPCBpatternforVINandSWshouldbeasbroadasVINCapacitorshouldbecedasnearaspossibletotheThetopsidepowerground(PGND)copperfillareaneartheICshouldbeaslargeaspossible.ThiswillaidinthermaldissipationaswelllowerconductionlossesinthegroundreturnExposedpadofdevicemustbeconnectedtoPGNDwithsolder.ThePGNDareaundertheICshouldbeaslargeaspossibleandcompleycovertheexposedthermalpad.Thebottomsideoftheboardshouldcontainalargecopperareaunderthedevicethatisdirectlyconnectedtotheexposedareawithsmalldiametervias.Smalldiameterviaswillpreventsolderfrombeingdrawnawayfromtheexposedthermalpad.Anyadditionalinternallayersshouldalsocontaincoppergroundareasunderthedeviceandbeconnectedtothethermalvias.ConnectiontoVIAtoGround EtchonBottomLayerorUnderFigure16.PCBPACKAGEOPTION11-Apr-PACKAGINGOrderablePackageEcoLead/BallMSLPeakOpTempTop-Side&noSb/Br)CU-40to&noSb/Br)CU-40to(1)ThemarketingstatusvaluesaredefinedasACTIVE:Product mendedfornewLIFEBUY:TIhasannouncedthatthedevicewillbedis,andalifetime-buyperiodisinNRND: mendedfornewdesigns.Deviceisinproductiontosupportexistingcustomers,butTIdoes mendusingthispartinanewPREVIEW:Devicehasbeenannouncedbutisnotinproduction.SamplesmayormaynotbeOBSOLETE:TIhasdistheproductionofthe(2)Econ-Thennedeco-friendlyclassification:Pb-(RoHS),Pb-(RoHSExempt),orGreen(RoHS&noSb/Br)-pleasecheck informationandadditionalproductcontentdetails.TBD:ThePb-/Green nhasnotbeenPb-(RoHS):TI'sterms"Lead- "or"Pb-"meansemiconductorproductsthatarecompatiblewiththecurrentRoHSrequirementsforall6substances,includingtherequirementthatleadnotexceed0.1%byweightinhomogeneousmaterials.Wheredesignedtobesolderedathightemperatures,TIPb-productsaresuitableforuseinspecifiedlead-processes.Pb-(RoHSExempt):ThiscomponenthasaRoHSexemptionforeither1)lead-basedflip-chipsolderbumpsusedbetweenthedieandpackage,or2)lead-baseddieadhesiveusedbetweenthedieandleadframe.ThecomponentisotherwiseconsideredPb-(RoHScompatible)asdefinedabove.Green(RoHS&noSb/Br):TIdefines"Green"tomeanPb-(RoHScompatible)