設(shè)計(jì)參考源碼手冊(cè)1746個(gè)zhcs270c

ZHCS270C–AUGUST2011–REVISEDAPRIL查詢樣品 (HSSTOP)PWP)4mmx4mm 線(RGE)封

DSL對(duì)每個(gè)通道的控制，從而提供電源排序的靈活性。每個(gè)通道的軟啟動(dòng)時(shí)間可通過(guò)選擇不同的外部電阻器來(lái)調(diào)下限制MOSFET功率耗散。低側(cè)反向電流保護(hù)還能夠防止過(guò)多吸收電流損壞轉(zhuǎn)換器。求，減輕電磁干擾(EMI)以及對(duì)輸入電容器的需求，兩個(gè)轉(zhuǎn)換器具有相移為180°的時(shí)鐘信號(hào)。4mmx4mm(RGE)封裝。Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsTexasInstrumentssemiconductorproductsand erstheretoappearsattheendofthisdataCopyright?2011–2012,TexasInstrumentsPowerPADisatrademarkCopyright?2011–2012,TexasInstrumentsPRODUCTIONDATAinformationiscurrentasofpublicationdate.ProductsconformtospecificationsperthetermsoftheInstrumentsstandardwarranty.Productionprocessingdoes EnglishDataSheet:necessarilyincludetestingofallThisintegratedcircuitcanbedamagedbyESD.TexasInstruments mendsthatallintegratedcircuitsbehandledwithappropriateprecautions.Failuretoobserveproperhandlingandinstallationprocedurescancausedamage.ESDdamagecanrangefromsubtleperformancedegradationtocompletedevicefailure.Precisionintegratedcircuitsmaybemoresusceptibletodamagebecauseverysmallparametricchangescouldcausethedevicenottomeetitspublishedspecifications.124124ENABLEBuck 2.2nF3 4 5LOW6 78 9 2.2nF ENABLEBuck789 789FUNCTIONALBLOCKLOWLOWPVCC23ROSC24 21,22SS1 FB1COMP119,20EN1EN29sameasBuck14BST2AGNDCurrentBiasNote:PinnumbersinblockdiagramareforHTSSOP(PWP)24pinORDERINGORDERABLEPARTTOP-SIDE–40°CtoPWP(R-PDSO-RGE(S-PVQFN-TPS65270RGERorForthemostcurrentpackageandorderinginformation,seethePackageOptionAddendumattheendofthis,orseetheTIwebsiteatPackagedrawings,thermaldata,andsymbolizationareavailable PIN(TOPVIEW)1234LOW56Thermal789ExposedpadmustbesolderedtoPCBforoptimalthermal(TOPVIEW)

ExposedpadmustbesolderedtoPCBforoptimalthermalTERMINAL1EnableforBuck1.LogichighenablestheBuck1;LogiclowdisablesBuck1.Ifpinisleftopenaweakinternalpull-uptoV5Vwillallowforautomaticenable;Foradelayedstart-upaddasmallceramiccapacitorfromthispintoground.2FeedbackvoltageforBuck1.Connectaresistordividertoset0.8Vfromtheoutputoftheconvertertoground.3SoftstartinputforBuck1.Aninternal5-μAchargingcurrentissourcingtothispin.ConnectasmallceramiccapacitortothispintosettheBuck1softstarttime.4LoopcompensationpinforBuck1.ConnectaseriesRCcircuittothispintocompensatethecontrolloopofthisconverter.5Lowpoweroperationmode.Withactivehigh,Buck1andBuck2operateatpulseskip modeatlightload;activelowsbothBuck1andBuck2to mode;thispincan’tbeleftopen.6Internal6.5-Vpowersupplybias.Connecta10-μFceramiccapacitorfromthispintoground.7ogground.ConnectallGNDpinsandpowerpad8Oscillatorfrequencysetup.Connectaresistortogroundtosetthefrequencyofinternaloscillatorclock.9LoopcompensationpinforBuck2.ConnectaseriesRCcircuittothispintocompensatethecontrolloopofthisconverter.1SoftstartinputforBuck2.Aninternal5-μAchargingcurrentissourcingtothispin.ConnectasmallceramiccapacitortothispintosettheBuck1softstarttime.2FeedbackvoltageforBuck2.Connectaresistordividertoset0.8Vfromtheoutputoftheconvertertoground.3EnableforBuck2.LogichighenablestheBuck2.LogiclowdisablesBuck2.Ifpinisleftopenaweakinternalpull-uptoV5Vwillallowforautomaticenable;Foradelayedstart-upaddasmallceramiccapacitorfromthispintoground.4BootstrappedpowersupplytohighsidefloatinggatedriverinBuck2.Connecta47-nFceramiccapacitorfromthispintotheswitchingnodepin5InputsupplyforBuck2.Connecta10-μFceramiccapacitorclosetothis15,6,SwitchingnodeconnectingtoinductorforBuck17,18,19,8,9,10,PowergroundforBuck1andBuck21,12,SwitchingnodeconnectingtoinductorforBuckInputsupplyforBuck1.Connecta10-μFceramiccapacitorclosetothisBootstrappedpowersupplytohighsidefloatinggatedriverinBuck1.Connecta47-nFceramiccapacitorfromthispintotheswitchingnodepinThermalMustbesolderedtoPCBforoptimalthermalperformance.HavethermalviasonthePCBtoenhancepowerdissipation. UMRATINGSoveroperating-airtemperaturerange(unlessotherwiseVoltagerangeatVIN1,VIN2,LX1,–0.3toVVoltagerangeatLX1,LX2(umwithstandvoltagetransient<10–1toVVoltageatBST1,BST2,referencedtoLX1,LX2–0.3toVVoltageatVCC,EN1,EN2,COMP1,COMP2,–0.3toVVoltageatSS1,SS2,FB1,FB2,–0.3toVVoltageatAGND,–0.3toV Operatingvirtualjunctiontemperature–40to Storagetemperature–55toStressesbeyondthoselistedunder"absolute umratings"maycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunder" mendedoperatingconditions"isnotimplied.Exposuretoabsolute–um–ratedconditionsforextendedperiodsmayaffectdevicereliability.MENDEDOPERATINGover -airtemperaturerange(unlessotherwiseInputoperatingVAmbientELECTROSTATICDISCHARGE(ESD) HumanbodymodelVChargedevicemodelVPACKAGEDISSIPATIONθJAθJCTA=25°CTA=55°CTA=85°CThisassumesaJEDECJESD51-5standardboardwiththermalviaswithHighKprofile-SeeTexasInstrumentsapplicationreport(SLMA002)regardingthermalcharacteristicsofthePowerPAD?package.ThisassumesjunctiontoexposedBasedonJEDEC51.5HIGHKenvironmentmeasuredona76.2x114x.6-mmboardwiththefollowinglayerToplayer:2OzCu,6.7%Layer2:1OzCu,90%Layer3:1OzCu,90%Bottomlayer:2OzCu,20%ELECTRICALTA=-40°Cto125°C,VIN=12V,fSW=625kHz(unlessotherwiseTESTINPUT InputVoltageVIN1andV EN1=EN2=0 NonswitchingquiescentpowerVFB1=VFB2=900LOW_P=1 VINundervoltageRisingV4VFalling InternalbiasingVCCloadcurrent=0A,VIN=12VV VCCLDODrop-OutVIN=5VCCloadcurrent=20 VCCcurrent4.5V<VIN<18FEEDBACKANDERROR RegulatedfeedbackVIN=12V,VCOMP=1.2V,TJ=25°CVVIN=12V,VCOMP=1.2V,TJ=-40°Cto125°CVL Lineregulation-VIN=4.5Vto18V,IOUT=1A Loadregulation-IOUT=10%-90% Erroramplifiertrans--2μA<ICOMP<2 COMPvoltagetoinductorcurrentILX=0.5ENABLE,PFMMODEANDSOFT- EN1andEN2pinV PSMlowpowermodeV SS1andSS2soft-startcharging5 SwitchingfrequencySetbyexternalresistor bleROSC=2501ROSC=500IL Buck1peakinductorcurrent4.5V<VIN<18AIL Buck1lowsideMOSFETcurrent4.5V<VIN<182AIL Buck2peakinductorcurrent4.5V<VIN<AIL Buck2lowsideMOSFETcurrent4.5V<VIN<182AMOSFETON- OnofhighsideFETonBST1toLX1=6.25 OnoflowsideFETonVIN=12 OnofhighsideFETonBST2toLX2=6.25 OnoflowsideFETonVIN=12 MinimuminTHERMALTTR ThermalprotectiontripRising ThermalprotectionTYPICALTA=25°C,VN=12V,fSW=625kHz(unlessotherwise ,Vout2,Vin=12 PSM,Vout2,Vin=12 Figure1.LoadRegulationBuck1at1.8V,1%Resistors

Figure2.LoadRegulationBuck1at1.2V,1%ResistorsVI=VI=4.5VI=15VI=120 Figure3.Buck1at3.3

Figure4.Buck2at1Vin=Vin=12VVout2=5Vautod 0 Figure5.Buck1at3.3

0 Figure6.Buck2at5TYPICALCHARACTERISTICS(TA=25°C,VIN=12V,fSW=625kHz(unlessotherwiseFigure7.Buck1andBuck2inSteadyState Figure8.Buck1andBuck2inSteadyStateIO1=0A,IO2=0A IO1=2A,IO2=3AFigure9.StartupWithEN Figure10.Buck1LoadTransientVO1=1.8V,VO2=1.2V VO1=3.3V,IO1=1A-2AFigure11.Buck2LoadTransient Figure12.Buck1andBuck2inPSMModeVO2=1V,IO1=1A-2ATYPICALCHARACTERISTICS(TA=25°C,VIN=12V,fSW=625kHz(unlessotherwiseFigure13.Buck2HardShortandTPS65270isapowermanagementICwithtwostep-downbuckconverters.Bothhigh-sideandlow-sideMOSFETsareintegratedtoprovidefullysynchronousconversionwithhigherefficiency.TPS65270cansupport4.5-Vto18-Vinputsupply,2-AcontinuouscurrentforBuck1and3AforBuck2.ThebuckconvertershaveanautomaticPSMmode,whichcanimprovepowerdissipationduringlightloads.Alternatively,thedeviceimplementsaconstantfrequencymodebyconnectingtheLOW_Ppintoground.Thewideswitchingfrequencyof300kHzto1.4MHzallowsforefficiencyandsizeoptimization.TheswitchingfrequencyisadjustablebyselectingaresistortogroundontheROSCpin.Inputrippleisreducedby180°out-of-phaseoperationbetweenBuck1andBuck2.Bothbuckconvertershavepeakcurrentmodecontrolwhichsimplifiestheloopcompensation.AtraditionaltypeIIcompensationnetworkcanstabilizethesystemandachievefasttransientresponse.Moreover,anoptionalcapacitorinparallelwiththeupperresistorofthefeedbackdividerprovidesonemorezeroandmakesthecrossoverfrequencyover100kHz.Eachbuckconverterhasanindividualcycle-by-cyclecurrentlimitandlowsidereversecurrentlimit.Thedevicehasabuilt-inLDOregulator.Duringastandbymode,the6.5-VLDOcanbeusedtodriveMCUandotheractiveloads.withthisLDO,systemisabletoturnoffthetwobuckconverterssoastoreducethepowerconsumptionandimprovethestandbyefficiency.Eachconverterhasitsownprogrblesoftstartthatcanreducetheinputinrushcurrent.TheindividualEnablepinsforeachindependentcontrolofeachoutputvoltageandpowersequence.DETAILEDAdjustableSwitchingToselecttheinternalswitchingfrequencyconnectaresistorfromROSCtoground.Figure14showstherequiredforagivenswitchingfrequency.--0 fsw-SwitchingFrequency- ( 239.13

Figure14.ROSCvsSwitching

Foroperationat800kHz,a300-k?resistorisOut-of-PhaseInordertoreduceinputripplecurrent,Buck1andBuck2operate180°out-of-phase.Thisenablesthesystemhavinglessinputripple,thentolowercomponentcost,saveboardspaceandreduceEMI.DelayedStart-Ifadelayedstart-upisrequiredonanyofthebuckconvertersfitaceramiccapacitortotheENxpins.Thedelayaddedis~0.75mspernFconnectedtothepin.NotethattheENpinshaveaweak1-M?pull-uptothe5-VSoftStart Thedevicehasaninternalpull-upcurrentsourceof5μAthatchargesanexternalslowstartcapacitortoimplementaslowstarttime.Equation2showshowtoselectaslowstartcapacitorbasedonanexpectedslowstarttime.Thevoltagereference(VREF)is0.8Vandtheslowstartchargecurrent(Iss)is T(ms)V(V) IAdjustingtheOutput

TheoutputvoltageissetwitharesistordividerfromtheoutputnodetotheFBpin.Itis mendedtouse1%toleranceorbetterdividerresistors.Inordertoimproveefficiencyatlightload,startwith40.2k?fortheR1resistorandusetheEquation3tocalculateR2.VR2R10.8VV +Figure15.VoltageDividerInputUse10-μFX7R/X5Rceramiccapacitorsattheinputoftheconverterinputs.Thesecapacitorsshouldbeconnectedascloseasphysicallypossibletotheinputpinsoftheconverters.BootstrapThedevicehastwointegratedbootregulatorsandrequiresasmallceramiccapacitorbetweentheBSTandLXpintoprovidethegatedrivevoltageforthehighsideMOSFET.Thevalueoftheceramiccapacitorismendedtobe0.047μF.AceramiccapacitorwithanX7RorX5RgradedielectricisdesiredbecauseofthestablecharacteristicsovertemperatureandErrorThedevicehasatransconductanceerroramplifier.Thetransconductanceoftheerroramplifieris130μA/Vduringnormaloperation.ThefrequencycompensationnetworkisconnectedbetweentheCOMPpinandground.LoopTPS65270isacurrentmodecontroldc/dcconverter.Theerroramplifierhas130-μA/VI/VGainFigure16.LoopAtypicalcompensationcircuitcouldbetypeII(RcandCc)tohaveaphasemarginbetween60and90degrees,ortypeIII(Rc,CcandCff)toimprovetheconvertertransientresponse.CRolladdsahighfrequencypoletoattenuatehigh-frequencynoisewhenneeded.Itmayalsopreventnoisecouplingfromotherrailsifthereispossibilityofcrosscouplinginbetweenrailswhenlayoutisverycompact.TocalculatetheexternalcompensationcomponentsfollowthefollowingTYPEIITYPEIIISelectswitchingfrequencythatisappropriateforapplicationdependingonL,Csizes,outputripple,EMIconcernsandetc.Switchingfrequenciesbetween500kHzand1MHzgivebesttradeoffbetweenperformanceandcost.WhenusingsmallerLandCs,switchingfrequencycanbeincreased.Tooptimizeefficiency,switchingfrequencycanbelowered.UsetypeIIIcircuitforswitchingfrequencieshigherthan500kHz.Selectcrossoverfrequency(fc)tobelessthan1/5to1/10ofswitchingfrequency.fc=fs/10fc=fs/10Setandcalculate2fcVogMVref2fcgMCalculateCcbycingacompensationzeroatorbeforetheconverterdominantpole c cAddCRollifneededtoremovelargesignalcouplingtohighimpedanceCOMPnode.Makesurethat 2R isatleasttwicethecrossover C CCalculateCffcompensationzeroatlowfrequencytoboostthephasemarginatthecrossoverfrequency.Makesurethatthezerofrequency(fzffissmallerthansoftstartequivalentfrequency(1/Tss). 2fz SlopeThedevicehasabuilt-inslopecompensationramp.Theslopecompensationcanpreventsubharmonicoscillationsinpeakcurrentmodecontrolwhendutycycle estoolarge.OverCurrentThecurrentthroughtheinternalhighsideMOSFETissampledandscaledthroughaninternalpilotdeviceduringthehigtime.Thesampledcurrentiscomparedtoovercurrentlimit.Ifthepeakinductorcurrentexceedstheovercurrentlimitreferencelevel,aninternalovercurrentfaultcounterissetto1andaninternalflagisset.TheinternalpowerMOSFETisimmediayturnedoffandwillnotbeturnedonagainuntilthenextswitchingcycle.TheprotectioncircuitrycontinuestomonitorthecurrentandturnsofftheinternalMOSFETasdescribed.Iftheovercurrentconditionpersistsforfoursequentialclockcycles,theover-currentfaultcounteroverflowsindicatinganovercurrentfaultconditionexists.Theregulatorisshutdownandpowergoodgoeslow.Iftheovercurrentconditionclearspriortothecounterreachingfourconsecutivecycles,theinternalflagandcounterarereset.Theprotectioncircuitryattemptstorecoverfromtheovercurrentconditionafterwaitingfoursoft-startcycles.Theinternalovercurrentflagandcounterarereset.Anormalsoft-startcycleisattemptedandnormaloperationcontinuesifthefaultconditionhascleared.Iftheovercurrentfaultcounteroverflowsduringsoft-start,theconvertershutsdownandthishiccupmodeoperationrepeats.ThermalThedeviceimplementsaninternalthermalshutdowntoprotectitselfifthejunctiontemperatureexceeds160°C.Thethermalshutdownsthedevicetostopswitchingwhenthejunctiontemperatureexceedsthermaltripthreshold.Oncethedietemperaturedecreasesbelow140°C,thedevicereinitiatesthepowerupsequence.Thethermalshutdownhysteresisis20°C.PowerThetotalpowerdissipationinsideTPS65270shouldnottoexceedthe umallowablejunctiontemperatureof125°Ctomaintainreliableoperation. umallowablepowerdissipationisafunctionoftheofthepackage(RJA)andambientTocalculatethetemperatureinsidethedeviceundercontinuousloadingusethefollowingDefinethesetvoltageforeachDefinethecontinuousloadingoneachconverter.MakesuredonotexceedtheconverterumDeterminefromthegraphsbelowtheexpectedlossesinwattsperconverterinsidethedevice.Thelossesdependontheinputsupply,theselectedswitchingfrequency,theoutputvoltageandtheconverterchosen.TocalculatetheumtemperatureinsidetheICusethefollowing T+ HOT TAistheambientPDISisthesumoflossesinallθJAisthejunctiontoambientthermalimpedanceofthedeviceanditisheavilydependantonboard

I

2.4 IFigure17.Buck Figure18.BuckVIN=12V,fSW=500 VIN=12V,fSW=1.1VO(fromtoptobottom)=5V,3.3 VO(fromtoptobottom)=5V,3.32.5V,1.8V,1.2 2.5V,1.8V,1.2

1.82.833.2IFigure19.Buck2VIN=12V,fSW=500kHz

1.82.833.2IFigure20.Buck2VIN=12V,fSW=1.1MHz

VO(fromtoptobottom)=5V,3.3 VO(fromtoptobottom)=5V,3.32.5V,1.8V,1.2 2.5V,1.8V,1.2LowPowerModeBypullingtheLow_Ppinhighallconverterswilloperateinpulse-skipmode,greatlyreducingtheoverallpowerconsumptionatlightandnoloadconditions.WhenLOW_Pistiedtolow,allconvertersrunindThermalThedeviceimplementsaninternalthermalshutdowntoprotectitselfifthejunctiontemperatureexceeds160°C.Thethermalshutdownsthedevicetostopswitchingwhenthejunctiontemperatureexceedsthermaltripthreshold.Oncethedietemperaturedecreasesbelow140°C,thedevicereinitiatesthepowerupsequence.Thethermalshutdownhysteresisis20°C. LayoutisacriticalportionofPMICceVOUT,andLXonthetoplayerandaninnerpowerneforFitalsoonthetoplayerconnectionsfortheremainingpinsofthePMICandalargetopsideareafilledwithThetoplayergroundareasouldbeconnectedtothebottomgroundlayer(s)usingviasattheinputbypasscapacitor,theoutputfiltercpacitoranddirectlyundertheTPS65270devicetoprovideathermalpathfromthePowerpadlandtoground.TheAGNDpinshouldbetieddirectlytothepowerpadundertheICandthepowerForoperationatfullratedload,thetopsidegroundareatogetherwiththebottomgroundne,mustprovideadequateheatdissipatingarea.Thereareseveralsignalspathsthatconductfastchangingcurrentsorvoltagesthatcaninctwithstrayinductanceorparasiticcapacitancetogeneratenoiseordegradethepowersperformance.Tohelpeliminatetheseproblems,theVINpinshouldbebypassedtogroundwithalowESRceramicbypasscapacitorwithX5RorX7Rdielectric.Careshouldbetakentominimizetheloopareaformedbythebypasscapacitorconnections,theVINpins,andthegroundconnections.SincetheLXconnectionistheswitchingnode,theoutputinductorshouldbelocatedclosetotheLXpins,andtheareaofthePCBconductorminimizedtopreventexcessivecapacitivecoupling.TheoutputfiltercapacitorgroundshouldusethesamepowergroundtraceastheVINinputbypasscapacitor.Trytominimizethisconductorlengthwhilemaintainingadequatewidth.ThecompensationshouldbeascloseaspossibletotheCOMPpins.TheCOMPandOSCpinsaresensitivetonoisesothecomponentsassociatedtothesepinsshouldbelocatedascloseaspossibletotheICandroutedwithminimallengthsoftrace.PACKAGEOPTIONPACKAGINGOrderableStatusPackagePackageEcon MSLPeakTempBall&noSb/Br)Call &noSb/Br)CUNIPDAUAGLevel-2-260C-1&noSb/Br)CUNIPDAUAGLevel-2-260C-1(1)ThemarketingstatusvaluesaredefinedasACTIVE:Product mendedfornewLIFEBUY:TIhasannouncedthatthedevicewillbedis,andalifetime-buyperiodisin 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)asdef