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TPS54628www.
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com.
cnZHCSB00–APRIL2013具具有有Eco-mode的的4.
5V至至18V输输入入,,6A同同步步降降压压转转换换器器查查询询样样品品:TPS546281特特性性说说明明23D-CAP2模模式式支支持持快快速速瞬瞬态态响响应应TPS54628是一款自适应接通时间D-CAP2模式同步降压转换器.
TPS54628可帮助系统设计人员通过低低输输出出纹纹波波,,支支持持陶陶瓷瓷输输出出电电容容器器一个成本有效、低组件数量、低待机电流解决方案来完宽宽泛泛的的VIN输输入入电电压压范范围围::4.
5V至至18V成各种终端设备的电源总线调节器集.
TPS54628的输输出出电电压压范范围围::0.
76V至至5.
5V主控制环路使用D-CAP2模式控制,此控制方式在高高效效率率集集成成型型场场效效应应晶晶体体管管(FET)针针对对较较低低占占空空比比应应用用进进行行了了优优化化无需外部补偿组件的情况下提供快速瞬态响应.
自适-36m((高高侧侧))与与28m((低低侧侧))应接通时间控制支持较高负载状态下的脉宽调制关关断断时时的的高高效效率率,,流流耗耗不不足足10μA(PWM)模式与轻负载下的Eco-mode工作模式之间初初始始带带隙隙参参考考的的高高精精度度的无缝转换.
Eco-mode使TPS54628能够在较轻可可调调软软启启动动负载条件下保持高效率.
TPS54628的私有电路还使预预偏偏置置软软启启动动该器件可采用诸如高分子有机半导体固体电容器650kHz开开关关频频率率(fSW)(POSCAP)或SP-CAP等低等效串联电阻(ESR)输出逐逐周周期期过过流流限限制制电容器以及超低ESR陶瓷电容器.
该器件的工作输入电压介于4.
5V至18VVIN之间.
输出电压可在自自动动跳跳跃跃Eco-mode为为了了在在轻轻负负载载下下实实现现高高效效率率0.
76V与5.
5V之间进行设定.
该器件还特有一个可调应应用用范范围围软启动时间.
TPS54628采用8引脚DDA封装,并低低电电压压系系统统的的广广泛泛应应用用针对-40°C到85°C的工作温度范围内的运行而设–数数字字电电视视电电源源计.
–高高清清Blu-rayDisc播播放放器器–网网络络家家庭庭终终端端设设备备–数数字字机机顶顶盒盒(STB)1Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
2D-CAP2,Eco-modearetrademarksofTexasInstruments.
3Blu-rayDiscisatrademarkofBlu-rayDiscAssociation.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.
Copyright2013,TexasInstrumentsIncorporatedProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.
ProductionprocessingdoesnotEnglishDataSheet:SLVSBW5necessarilyincludetestingofallparameters.
TPS54628ZHCSB00–APRIL2013www.
ti.
com.
cnThesedeviceshavelimitedbuilt-inESDprotection.
TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
ORDERINGINFORMATION(1)TRANSPORTTAPACKAGE(2)(3)ORDERABLEPARTNUMBERPINMEDIATPS54628DDATube–40°Cto85°CDDA8TPS54628DDARTapeandReel(1)Forthemostcurrentpackageandorderinginformation,seethePackageOptionAddendumattheendofthisdocument,orseetheTIwebsiteatwww.
ti.
com.
(2)Packagedrawings,thermaldata,andsymbolizationareavailableatwww.
ti.
com/packaging.
(3)AllpackageoptionshaveCuNIPDAUlead/ballfinish.
ABSOLUTEMAXIMUMRATINGSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)(1)VALUEUNITMINMAXVIN,EN–0.
320VBST–0.
326VBST(10nstransient)–0.
328InputvoltagerangeVBST(vsSW)–0.
36.
5VVFB,SS–0.
36.
5SW–220SW(10nstransient)–322VREG5–0.
36.
5OutputvoltagerangeVGND–0.
30.
3VoltagefromGNDtothermalpad,Vdiff–0.
20.
2VHumanBodyModel(HBM)2kVElectrostaticdischargeChargedDeviceModel(CDM)500VOperatingjunctiontemperature,TJ–40150°CStoragetemperature,Tstg–55150(1)Stressesbeyondthoselistedunderabsolutemaximumratingsmaycausepermanentdamagetothedevice.
Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunderrecommendedoperatingconditionsisnotimplied.
Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmayaffectdevicereliability.
THERMALINFORMATIONTPS54628THERMALMETRIC(1)UNITSDDA(8PINS)θJAJunction-to-ambientthermalresistance43.
5θJCtopJunction-to-case(top)thermalresistance49.
4θJBJunction-to-boardthermalresistance25.
6°C/WψJTJunction-to-topcharacterizationparameter7.
4ψJBJunction-to-boardcharacterizationparameter25.
5θJCbotJunction-to-case(bottom)thermalresistance5.
2(1)Formoreinformationabouttraditionalandnewthermalmetrics,seetheICPackageThermalMetricsapplicationreport,SPRA953.
2Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013RECOMMENDEDOPERATINGCONDITIONSoveroperatingfree-airtemperaturerange,(unlessotherwisenoted)MINMAXUNITVINSupplyinputvoltagerange4.
518VVBST–0.
124VBST(10nstransient)–0.
127VBST(vsSW)–0.
16.
0SS–0.
15.
7VIInputvoltagerangeEN–0.
118VVFB–0.
15.
5SW–1.
818SW(10nstransient)–321GND–0.
10.
1VOOutputvoltagerangeVREG5–0.
15.
7VIOOutputCurrentrangeIVREG505mATAOperatingfree-airtemperature–4085°CTJOperatingjunctiontemperature–40150°CELECTRICALCHARACTERISTICSoveroperatingfree-airtemperaturerange,VIN=12V(unlessotherwisenoted)PARAMETERTESTCONDITIONSMINTYPMAXUNITSUPPLYCURRENTVINcurrent,TA=25°C,EN=5V,IVINOperating-non-switchingsupplycurrent9501400μAVFB=0.
8VIVINSDNShutdownsupplycurrentVINcurrent,TA=25°C,EN=0V310μALOGICTHRESHOLDENhigh-levelinputvoltageEN1.
6VVENENlow-levelinputvoltageEN0.
6VRENENpinresistancetoGNDVEN=12V200400800kΩVFBVOLTAGEANDDISCHARGERESISTANCETA=25°C,VO=1.
05V,IO=10mA,Eco-772mVmodeoperationTA=25°C,VO=1.
05V,continuousmodeVFBTHVFBthresholdvoltage757765773mVoperationTA=-40to85°C,VO=1.
05V,continuous751765779mVmodeoperation(1)IVFBVFBinputcurrentVFB=0.
8V,TA=25°C0±0.
15μAVREG5OUTPUTTA=25°C,6V.
com.
cnELECTRICALCHARACTERISTICS(continued)overoperatingfree-airtemperaturerange,VIN=12V(unlessotherwisenoted)PARAMETERTESTCONDITIONSMINTYPMAXUNITTHERMALSHUTDOWNShutdowntemperature(2)165TSDNThermalshutdownthreshold°CHysteresis(2)35ON-TIMETIMERCONTROLtONOntimeVIN=12V,VO=1.
05V150nstOFF(MIN)MinimumofftimeTA=25°C,VFB=0.
7V260310nsSOFTSTARTSSchargecurrentVSS=1V4.
267.
8μAISSSSdischargecurrentVSS=0.
5V1.
53.
3mAHICCUPANDOVER-VOLTAGEPROTECTIONVOVPOutputOVPthresholdOVPDetect(L>H)125%VHICCUPOutputHiccupthresholdHiccupdetect(H>L)65%THICCUPDELAYOutputHiccupdelayTohiccupstate250secTHICCUPENDELAYOutputHiccupEnabledelayRelativetosoft-starttimex1.
7UVLOWakeupVREG5voltage3.
453.
754.
05UVLOUVLOthresholdVHysteresisVREG5voltage0.
130.
320.
48(2)Notproductiontested.
4Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013DEVICEINFORMATIONDDAPACKAGE(TOPVIEW)PINFUNCTIONSPINDESCRIPTIONNAMENO.
EN1Enableinputcontrol.
ENisactivehighandmustbepulleduptoenablethedevice.
VFB2Converterfeedbackinput.
Connecttooutputvoltagewithfeedbackresistordivider.
5.
5Vpowersupplyoutput.
Acapacitor(typical1F)shouldbeconnectedtoGND.
VREG5isnotactiveVREG53whenENislow.
SS4Soft-startcontrol.
AnexternalcapacitorshouldbeconnectedtoGND.
Groundpin.
Powergroundreturnforswitchingcircuit.
ConnectsensitiveSSandVFBreturnstoGNDatGND5asinglepoint.
SW6Switchnodeconnectionbetweenhigh-sideNFETandlow-sideNFET.
Supplyinputforthehigh-sideFETgatedrivecircuit.
Connect0.
1FcapacitorbetweenVBSTandSWVBST7pins.
AninternaldiodeisconnectedbetweenVREG5andVBST.
VIN8Inputvoltagesupplypin.
ExposedThermalThermalpadofthepackage.
Mustbesolderedtoachieveappropriatedissipation.
MustbeconnectedtoBacksidePadGND.
Copyright2013,TexasInstrumentsIncorporated5TPS54628ZHCSB00–APRIL2013www.
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cnFUNCTIONALBLOCKDIAGRAM6Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013OVERVIEWTheTPS54628isa6-AEco-modesynchronousstep-down(buck)converterwithtwointegratedN-channelMOSFETs.
ItoperatesusingD-CAP2modecontrol.
ThefasttransientresponseofD-CAP2controlreducestheoutputcapacitancerequiredtomeetaspecificlevelofperformance.
ProprietaryinternalcircuitryallowstheuseoflowESRoutputcapacitorsincludingceramicandspecialpolymertypes.
DETAILEDDESCRIPTIONPWMOperationThemaincontrolloopoftheTPS54628isanadaptiveon-timepulsewidthmodulation(PWM)controllerthatsupportsaproprietaryD-CAP2modecontrol.
D-CAP2modecontrolcombinesconstanton-timecontrolwithaninternalcompensationcircuitforpseudo-fixedfrequencyandlowexternalcomponentcountconfigurationwithbothlowESRandceramicoutputcapacitors.
Itisstableevenwithvirtuallynorippleattheoutput.
Atthebeginningofeachcycle,thehigh-sideMOSFETisturnedon.
ThisMOSFETisturnedoffafterinternaloneshottimerexpires.
Thisoneshotissetbytheconverterinputvoltage,VIN,andtheoutputvoltage,VO,tomaintainapseudo-fixedfrequencyovertheinputvoltagerange,henceitiscalledadaptiveon-timecontrol.
Theone-shottimerisresetandthehigh-sideMOSFETisturnedonagainwhenthefeedbackvoltagefallsbelowthereferencevoltage.
Aninternalrampisaddedtoreferencevoltagetosimulateoutputripple,eliminatingtheneedforESRinducedoutputripplefromD-CAP2modecontrol.
PWMFrequencyandAdaptiveOn-TimeControlTPS54628usesanadaptiveon-timecontrolschemeanddoesnothaveadedicatedonboardoscillator.
TheTPS54628runswithapseudo-constantfrequencyof650kHzbyusingtheinputvoltageandoutputvoltagetosettheon-timeone-shottimer.
Theon-timeisinverselyproportionaltotheinputvoltageandproportionaltotheoutputvoltage;therefore,whenthedutyratioisVOUT/VIN,thefrequencyisconstant.
Auto-SkipEco-ModeControlTheTPS54628isdesignedwithAuto-SkipEco-modetoincreaselightloadefficiency.
Astheoutputcurrentdecreasesfromheavyloadcondition,theinductorcurrentisalsoreducedandeventuallycomestopointthatitsrippledvalleytoucheszerolevel,whichistheboundarybetweencontinuousconductionanddiscontinuousconductionmodes.
TherectifyingMOSFETisturnedoffwhenitszeroinductorcurrentisdetected.
Astheloadcurrentfurtherdecreasestheconverterrunintodiscontinuousconductionmode.
Theon-timeiskeptalmostthesameasiswasinthecontinuousconductionmodesothatittakeslongertimetodischargetheoutputcapacitorwithsmallerloadcurrenttothelevelofthereferencevoltage.
ThetransitionpointtothelightloadoperationIOUT(LL)currentcanbecalculatedinEquation1(1)SoftStartandPre-BiasedSoftStartThesoftstartfunctionisadjustable.
WhentheENpinbecomeshigh,6μAcurrentbeginschargingthecapacitorwhichisconnectedfromtheSSpintoGND.
Smoothcontroloftheoutputvoltageismaintainedduringstartup.
TheequationfortheslowstarttimeisshowninEquation2.
VFBvoltageis0.
765VandSSpinsourcecurrentis6μA.
(2)TheTPS54628containsauniquecircuittopreventcurrentfrombeingpulledfromtheoutputduringstartupiftheoutputispre-biased.
Whenthesoft-startcommandsavoltagehigherthanthepre-biaslevel(internalsoftstartbecomesgreaterthanfeedbackvoltageVFB),thecontrollerslowlyactivatessynchronousrectificationbystartingthefirstlowsideFETgatedriverpulseswithanarrowon-time.
Itthenincrementsthaton-timeonacycle-by-cyclebasisuntilitcoincideswiththetimedictatedby(1-D),whereDisthedutycycleoftheconverter.
Thisschemepreventstheinitialsinkingofthepre-biasoutput,andensurethattheoutvoltage(VO)startsandrampsupsmoothlyintoregulationandthecontrolloopisgiventimetotransitionfrompre-biasedstart-uptonormalmodeoperation.
Copyright2013,TexasInstrumentsIncorporated7TPS54628ZHCSB00–APRIL2013www.
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cnOutputDischargeControlTPS54628dischargestheoutputwhenENislow,orthecontrolleristurnedoffbytheUVLOprotection.
Theinternallow-sideMOSFETisnotturnedonfortheoutputdischargeoperationtoavoidthepossibilityofcausingnegativevoltageattheoutput.
CurrentProtectionTheoutputovercurrentprotection(OCP)isimplementedusingacycle-by-cyclevalleydetectcontrolcircuit.
Theswitchcurrentismonitoredbymeasuringthelow-sideFETswitchvoltagebetweentheSWpinandGND.
Thisvoltageisproportionaltotheswitchcurrent.
Toimproveaccuracy,thevoltagesensingistemperaturecompensated.
Duringtheontimeofthehigh-sideFETswitch,theswitchcurrentincreasesatalinearratedeterminedbyVIN,VOUT,theon-timeandtheoutputinductorvalue.
Duringtheontimeofthelow-sideFETswitch,thiscurrentdecreaseslinearly.
TheaveragevalueoftheswitchcurrentistheloadcurrentIOUT.
TheTPS54628constantlymonitorsthelow-sideFETswitchvoltage,whichisproportionaltotheswitchcurrent,duringthelow-sideon-time.
Ifthemeasuredvoltageisabovethevoltageproportionaltothecurrentlimit,aninternalcounterisincrementedpereachSWcycleandtheconvertermaintainsthelow-sideswitchonuntilthemeasuredvoltageisbelowthevoltagecorrespondingtothecurrentlimitatwhichtimetheswitchingcycleisterminatedandanewswitchingcyclebegins.
Insubsequentswitchingcycles,theon-timeissettoafixedvalueandthecurrentismonitoredinthesamemanner.
Iftheovercurrentconditionexistsfor7consecutiveswitchingcycles,theinternalOCLthresholdissettoalowerlevel,reducingtheavailableoutputcurrent.
WhenaswitchingcycleoccurswheretheswitchcurrentisnotabovethelowerOCLthreshold,thecounterisresetandtheOCLlimitisreturnedtothehighervalue.
Therearesomeimportantconsiderationsforthistypeofover-currentprotection.
Thepeakcurrentistheaverageloadcurrentplusonehalfofthepeak-to-peakinductorcurrent.
Thevalleycurrentistheaverageloadcurrentminusonehalfofthepeak-to-peakinductorcurrent.
Sincethevalleycurrentisusedtodetecttheover-currentthreshold,theloadcurrentishigherthantheover-currentthreshold.
Also,whenthecurrentisbeinglimited,theoutputvoltagetendstofall.
WhentheVFBvoltagebecomeslowerthan65%ofthetargetvoltage,theUVPcomparatordetectsit.
Iftheunder-voltageconditionpersistsfor250s,thedevicewillshutdownandre-startinhiccupmodeafter7timestheSSperiod.
Whentheovercurrentconditionisremoved,theoutputvoltagewillreturntotheregulatedvalue.
Thisprotectionisnon-latching.
OverVoltageProtectionTPS54628detectsoverandundervoltageconditionsbymonitoringthefeedbackvoltage(VFB).
Thisfunctionisenabledafterapproximately1.
7xtimesthesoftstarttime.
Whenthefeedbackvoltagebecomeshigherthan125%ofthetargetvoltage,theOVPcomparatoroutputgoeshighandboththehigh-sideMOSFETdriverandthelow-sideMOSFETdriverturnoff.
Thisfunctionisnon-latchoperation.
UVLOProtectionUndervoltagelockoutprotection(UVLO)monitorsthevoltageoftheVREG5pin.
WhentheVREG5voltageislowerthanUVLOthresholdvoltage,theTPS54628isshutoff.
Thisprotectionisnon-latching.
ThermalShutdownTPS54628monitorsthetemperatureofitself.
Ifthetemperatureexceedsthethresholdvalue(typically165°C),thedeviceisshutoff.
Thisisnon-latchprotection.
8Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013TYPICALCHARACTERISTICSVIN=12V,TA=25°C(unlessotherwisenoted).
Figure1.
SUPPLYCURRENTvsJUNCTIONTEMPERATUREFigure2.
VINSHUTDOWNCURRENTvsJUNCTIONTEMPERATUREFigure3.
ENCURRENTvsENVOLTAGEFigure4.
1.
05-VOUTPUTVOLTAGEvsOUTPUTCURRENTFigure5.
1.
05-VOUTPUTVOLTAGEvsINPUTVOLTAGEFigure6.
1.
05-V,LOADTRANSIENTRESPONSECopyright2013,TexasInstrumentsIncorporated9TPS54628ZHCSB00–APRIL2013www.
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cnTYPICALCHARACTERISTICS(continued)VIN=12V,TA=25°C(unlessotherwisenoted).
Figure7.
START-UPWAVEFORMFigure8.
EFFICIENCYvsOUTPUTCURRENTFigure9.
LIGHTLOADEFFICIENCYvsOUTPUTCURRENTFigure10.
SWITCHINGFREQUENCYvsINPUTVOLTAGEFigure11.
SWITCHINGFREQUENCYvsOUTPUTCURRENTFigure12.
VFBVOLTAGEvsJUNCTIONTEMPERATURE10Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013TYPICALCHARACTERISTICS(continued)VIN=12V,TA=25°C(unlessotherwisenoted).
Figure13.
VOLTAGERIPPLEATOUTPUT(IO=6A)Figure14.
DCMVOLTAGERIPPLEATOUTPUT(IO=30mA)Figure15.
VOLTAGERIPPLEATINPUT(IO=6A)Figure16.
OUTPUTCURRENTvsAMBIENTTEMPERATURECopyright2013,TexasInstrumentsIncorporated11TPS54628ZHCSB00–APRIL2013www.
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cnDESIGNGUIDEStep-By-StepDesignProcedureTobeginthedesignprocess,theusermustknowafewapplicationparameters:InputvoltagerangeOutputvoltageOutputcurrentOutputvoltagerippleInputvoltagerippleFigure17.
Showstheschematicdiagramforthisdesignexample.
OutputVoltageResistorsSelectionTheoutputvoltageissetwitharesistordividerfromtheoutputnodetotheVFBpin.
Itisrecommendedtouse1%toleranceorbetterdividerresistors.
StartbyusingEquation3tocalculateVOUT.
Toimproveefficiencyatlightloadsconsiderusinglargervalueresistors,highresistanceismoresusceptibletonoise,andthevoltageerrorsfromtheVFBinputcurrentaremorenoticeable.
(3)OutputFilterSelectionTheoutputfilterusedwiththeTPS54628isanLCcircuit.
ThisLCfilterhasdoublepoleat:(4)Atlowfrequencies,theoverallloopgainissetbytheoutputset-pointresistordividernetworkandtheinternalgainoftheTPS54628.
Thelowfrequencyphaseis180degrees.
Attheoutputfilterpolefrequency,thegainrollsoffata–40dBperdecaderateandthephasedropsrapidly.
D-CAP2introducesahighfrequencyzerothatreducesthegainrolloffto–20dBperdecadeandincreasesthephaseto90degreesonedecadeabovethezerofrequency.
TheinductorandcapacitorselectedfortheoutputfiltermustbeselectedsothatthedoublepoleofEquation4islocatedbelowthehighfrequencyzerobutcloseenoughthatthephaseboostprovidedbethehighfrequencyzeroprovidesadequatephasemarginforastablecircuit.
TomeetthisrequirementusethevaluesrecommendedinTable112Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013Table1.
RecommendedComponentValuesOutputC4(pF)(1)L1(H)C8+C9(F)VoltageR1(kΩ)R2(kΩ)MINTYPMAXMINTYPMAXMINMAX(V)16.
8122.
151502201.
01.
54.
722681.
058.
2522.
151502201.
01.
54.
722681.
212.
722.
151001.
01.
54.
722681.
521.
522.
15681.
01.
54.
722681.
830.
122.
15221.
21.
54.
722682.
549.
922.
15221.
52.
24.
722683.
373.
222.
12221.
82.
24.
72268512422.
12222.
23.
34.
72268(1)OptionalSincetheDCgainisdependentontheoutputvoltage,therequiredinductorvalueincreasesastheoutputvoltageincreases.
Additionalphaseboostcanbeachievedbyaddingafeedforwardcapacitor(C4)inparallelwithR1.
Thefeedforwardcapacitorismosteffectiveforoutputvoltagesatorabove1.
8V.
Theinductorpeak-to-peakripplecurrent,peakcurrentandRMScurrentarecalculatedusingEquation5,Equation6andEquation7.
TheinductorsaturationcurrentratingmustbegreaterthanthecalculatedpeakcurrentandtheRMSorheatingcurrentratingmustbegreaterthanthecalculatedRMScurrent.
Use700kHzforfSW.
Use650kHzforfSW.
MakesurethechoseninductorisratedforthepeakcurrentofEquation6andtheRMScurrentofEquation7.
(5)(6)(7)Forthisdesignexample,thecalculatedpeakcurrentis6.
51AandthecalculatedRMScurrentis6.
01A.
TheinductorusedisaTDKSPM6530-1R5M100withapeakcurrentratingof11.
6AandanRMScurrentratingof11A.
ThecapacitorvalueandESRdeterminestheamountofoutputvoltageripple.
TheTPS54628isintendedforusewithceramicorotherlowESRcapacitors.
Recommendedvaluesrangefrom22Fto68F.
UseEquation8todeterminetherequiredRMScurrentratingfortheoutputcapacitor.
(8)ForthisdesigntwoTDKC3216X5R0J226M22Foutputcapacitorsareused.
ThetypicalESRis2mΩeach.
ThecalculatedRMScurrentis0.
284Aandeachoutputcapacitorisratedfor4A.
InputCapacitorSelectionTheTPS54628requiresaninputdecouplingcapacitorandabulkcapacitorisneededdependingontheapplication.
Aceramiccapacitorover10μFisrecommendedforthedecouplingcapacitor.
Anadditional0.
1Fcapacitor(C3)frompin8togroundisoptionaltoprovideadditionalhighfrequencyfiltering.
Thecapacitorvoltageratingneedstobegreaterthanthemaximuminputvoltage.
BootstrapCapacitorSelectionA0.
1F.
ceramiccapacitormustbeconnectedbetweentheVBSTtoSWpinforproperoperation.
Itisrecommendedtouseaceramiccapacitor.
Copyright2013,TexasInstrumentsIncorporated13TPS54628ZHCSB00–APRIL2013www.
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cnVREG5CapacitorSelectionA1-F.
ceramiccapacitormustbeconnectedbetweentheVREG5toGNDpinforproperoperation.
Itisrecommendedtouseaceramiccapacitor.
THERMALINFORMATIONThis8-pinDDApackageincorporatesanexposedthermalpadthatisdesignedtobedirectlytoanexternalheartsick.
Thethermalpadmustbesoldereddirectlytotheprintedboard(PCB).
Aftersoldering,thePCBcanbeusedasaheartsick.
Inaddition,throughtheuseofthermalvias,thethermalpadcanbeattacheddirectlytotheappropriatecopperplaneshownintheelectricalschematicforthedevice,oralternatively,canbeattachedtoaspecialheartsickstructuredesignedintothePCB.
Thisdesignoptimizestheheattransferfromtheintegratedcircuit(IC).
Foradditionalinformationontheexposedthermalpadandhowtousetheadvantageofitsheatdissipatingabilities,seetheTechnicalBrief,PowerPADThermallyEnhancedPackage,TexasInstrumentsLiteratureNo.
SLMA002andApplicationBrief,PowerPADMadeEasy,TexasInstrumentsLiteratureNo.
SLMA004.
Theexposedthermalpaddimensionsforthispackageareshowninthefollowingillustration.
Figure18.
ThermalPadDimensions14Copyright2013,TexasInstrumentsIncorporatedTPS54628www.
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cnZHCSB00–APRIL2013LAYOUTCONSIDERATIONS1.
TheTPS54628cansupplylargeloadcurrentsupto6A,soheatdissipationmaybeaconcern.
ThetopsideareaadjacenttotheTPS54628shouldbefilledwithgroundasmuchaspossibletodissipateheat.
2.
ThebottomsideareadirectlybelowtheICshouldadedicatedgroundarea.
Itshouldbedirectlyconnectedtothethermalpadofthedeviceusingviasasshown.
Thegroundareashouldbeaslargeaspractical.
Additionalinternallayerscanbededicatedasgroundplanesandconnectedtotheviasaswell.
3.
Keeptheinputswitchingcurrentloopassmallaspossible.
4.
KeeptheSWnodeasphysicallysmallandshortaspossibletominimizeparasiticcapacitanceandinductanceandtominimizeradiatedemissions.
Kelvinconnectionsshouldbebroughtfromtheoutputtothefeedbackpinofthedevice.
5.
Keepanalogandnon-switchingcomponentsawayfromswitchingcomponents.
6.
Makeasinglepointconnectionfromthesignalgroundtopowerground.
7.
Donotallowswitchingcurrenttoflowunderthedevice.
8.
KeepthepatternlinesforVINandPGNDbroad.
9.
ExposedpadofdevicemustbeconnectedtoPGNDwithsolder.
10.
VREG5capacitorshouldbeplacednearthedevice,andconnectedPGND.
11.
OutputcapacitorshouldbeconnectedtoabroadpatternofthePGND.
12.
Voltagefeedbackloopshouldbeasshortaspossible,andpreferablywithgroundshield.
13.
LowerresistorofthevoltagedividerwhichisconnectedtotheVFBpinshouldbetiedtoSGND.
14.
ProvidingsufficientviaispreferableforVIN,SWandPGNDconnection.
15.
PCBpatternforVIN,SW,andPGNDshouldbeasbroadaspossible.
16.
VINCapacitorshouldbeplacedasnearaspossibletothedevice.
Figure19.
PCBLayoutCopyright2013,TexasInstrumentsIncorporated15PACKAGEOPTIONADDENDUMwww.
ti.
com10-Dec-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Leadfinish/Ballmaterial(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesTPS54628DDAACTIVESOPowerPADDDA875RoHS&GreenNIPDAU|SNLevel-2-260C-1YEAR-40to15054628TPS54628DDARACTIVESOPowerPADDDA82500RoHS&GreenNIPDAU|SNLevel-2-260C-1YEAR-40to15054628(1)Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.
Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.
Samplesmayormaynotbeavailable.
OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)RoHS:TIdefines"RoHS"tomeansemiconductorproductsthatarecompliantwiththecurrentEURoHSrequirementsforall10RoHSsubstances,includingtherequirementthatRoHSsubstancedonotexceed0.
1%byweightinhomogeneousmaterials.
Wheredesignedtobesolderedathightemperatures,"RoHS"productsaresuitableforuseinspecifiedlead-freeprocesses.
TImayreferencethesetypesofproductsas"Pb-Free".
RoHSExempt:TIdefines"RoHSExempt"tomeanproductsthatcontainleadbutarecompliantwithEURoHSpursuanttoaspecificEURoHSexemption.
Green:TIdefines"Green"tomeanthecontentofChlorine(Cl)andBromine(Br)basedflameretardantsmeetJS709Blowhalogenrequirementsof.
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