TPS61085
SLVS859A–JUNE2008–REVISEDAPRIL2012
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650kHz/1.2MHz,18.5VSTEP-UPDC-DCCONVERTER
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FEATURES
2.3Vto6VInputVoltageRange
18.5VBoostConverterWith2.0ASwitchCurrent
650kHz/1.2MHzSelectableSwitchingFrequency
AdjustableSoft-StartThermalShutdownUndervoltageLockout8-PinMSOPPackage8-PinTSSOPPackage
••••••••
APPLICATIONS
•••••••
HandheldDevicesGPSReceiver
DigitalStillCameraPortableApplicationsDSLModemPCMCIACard
TFTLCDBiasSupply
DESCRIPTION
TheTPS61085isahighfrequency,highefficiencyDCtoDCconverterwithanintegrated2.0A,0.13Ωpowerswitchcapableofprovidinganoutputvoltageupto18.5V.Theselectablefrequencyof650kHzor1.2MHzallowstheuseofsmallexternalinductorsandcapacitorsandprovidesfasttransientresponse.Theexternalcompensationallowsoptimizingtheapplicationforspecificconditions.Acapacitorconnectedtothesoft-startpinminimizesinrushcurrentatstartup.
L3.3mH
VIN2.3 V to 6 VCBY1µF16 V6INSW5DPMEG2010AEHR1158 kΩR218.2 kΩRCOMP51 kΩCCOMP1.1 nFVS12 V/300 mACIN10µF16 V3ENFB2COUT2* 10 µF25 V7FREQCOMP14GNDTPS61085SS8CSS100 nFPleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.ProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.Productionprocessingdoesnotnecessarilyincludetestingofallparameters.
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Thesedeviceshavelimitedbuilt-inESDprotection.TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
ORDERINGINFORMATION(1)
TA–40to85°C–40to85°C(1)(2)
ORDERINGTPS61085DGKTPS61085PW
PACKAGEMSOP-8(DGK)TSSOP-8(PW)
(2)
PACKAGEMARKING
PMKI61085
TheDGKandPWpackagesareavailabletapedandreeled.
Forthemostcurrentpackageandorderinginformation,seethePackageOptionAddendumattheendofthisdocument,orseetheTIwebsiteatwww.ti.com.
ABSOLUTEMAXIMUMRATINGS
overoperatingfree-airtemperaturerange(unlessotherwisenoted)(1)(2)
VALUE
InputvoltagerangeIN
VoltagerangeonpinsEN,FB,SS,FREQ,COMPVoltageonpinSWESDratingHBMESDratingMMESDratingCDM
ContinuouspowerdissipationOperatingjunctiontemperaturerangeStoragetemperaturerange(1)(2)
–0.3to7–0.3to7-0.3to20
2200500
SeeDissipationRatingTable
–40to150–65to150
°C°CUNITVVVkVVV
Stressesbeyondthoselistedunderabsolutemaximumratingsmaycausepermanentdamagetothedevice.Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunderrecommendedoperatingconditionsisnotimplied.Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmayaffectdevicereliabilityAllvoltagevaluesarewithrespecttonetworkgroundterminal.
DISSIPATIONRATINGS(1)
PACKAGEMSOPTSSOP(1)(2)
RθJA181°C/W160°C/W
TA≤25°CPOWERRATING
552mW625mW
(2)
TA=70°CPOWERRATING
303mW343mW
TA=85°CPOWERRATING
221mW250mW
PD=(TJ–TA)/RθJA.
RθJA.givenforHigh-KPCBboard.
RECOMMENDEDOPERATINGCONDITIONS
MIN
VINVSTATJ
InputvoltagerangeBoostoutputvoltagerangeOperatingfree-airtemperatureOperatingjunctiontemperature
2.3VIN+0.5
–40–40
TYP
MAX
618.585125
UNITVV°C°C
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ELECTRICALCHARACTERISTICS
VIN=3.3V,EN=VIN,VS=12V,TA=–40°Cto85°C,typicalvaluesareatTA=25°C(unlessotherwisenoted)
PARAMETER
SUPPLYVINIQISDVINUVLOTSDTSD(HYS)VIHVILIlkgVSVFBgmIFBrDS(on)IlkgILIMISSfS
Inputvoltagerange
OperatingquiescentcurrentintoINShutdowncurrentintoINUndervoltagelockoutthresholdThermalshutdown
ThermalshutdownhysteresisHighlevelinputvoltageLowlevelinputvoltageInputleakagecurrentBoostoutputvoltageFeedbackregulationvoltageTransconductanceerroramplifierFeedbackinputbiascurrentN-channelMOSFETon-resistanceSWleakagecurrent
N-ChannelMOSFETcurrentlimitSoft-startcurrentOscillatorfrequencyLineregulationLoadregulation
VSS=1.238VFREQ=VINFREQ=GND
VIN=2.3Vto6V,IOUT=10mAVIN=3.3V,IOUT=1mAto400mAVFB=1.238V
VIN=VGS=5V,ISW=currentlimitVIN=VGS=3.3V,ISW=currentlimitEN=GND,VSW=6VTBD
2.070.9480
2.6101.26500.00020.110.130.15
VIN=2.3Vto6VVIN=2.3Vto6VEN=FREQ=GND
VIN+0.51.230
1.238107
0.10.200.24103.2131.5820
µAAμAMHzkHz%/V%/A
2
0.50.118.51.246
Devicenotswitching,VFB=1.3VEN=GNDVINfallingVINrising
Temperaturerising
15014
2.3
70
610012.22.3
VμAμAVV°C°CVVμAVVμA/VμAΩ
TESTCONDITIONS
MIN
TYP
MAX
UNIT
LOGICSIGNALSEN,FREQ
BOOSTCONVERTER
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PINASSIGNMENT
DGK,PWPACKAGES
(TOPVIEW)
COMP
FBENPGND
1234
8765
SSFREQINSW
8-PIN4.9mmx3mmx1.1mmMSOP(DGK)8-PIN6.4mmx3mmx1.2mmTSSOP(PW)
PINFUNCTIONS
PINNAMECOMPFBENPGNDSWINFREQSS
NO.12345678
II/OI/OII
CompensationpinFeedbackpin
Shutdowncontrolinput.ConnectthispintologichighleveltoenablethedevicePowergroundSwitchpinInputsupplypin
Frequencyselectpin.Thepowerswitchoperatesat650kHzifFREQisconnectedtoGNDandat1.2MHzifFREQisconnectedtoIN
Soft-startcontrolpin.Connectacapacitortothispinifsoft-startneeded.Open=nosoft-start
DESCRIPTION
spaceTYPICALCHARACTERISTICS
TABLEOFGRAPHS
FIGURE
IOUT(max)η
MaximumloadcurrentEfficiency
PWMswitching-discontinuousconductionPWMswitching-continuousconductionLoadtransientresponseLoadtransientresponseSoft-startSupplycurrentFrequencyFrequency
vsSupplyvoltagevsLoadcurrentvsSupplyvoltage
atHighfrequency(1.2MHz)atLowfrequency(650kHz)
vsInputvoltageathighfrequency(1.2MHz)vsInputvoltageatlowfrequency(650kHz)vsLoadcurrent,VS=12V,VIN=3.3VvsLoadcurrent,VS=9V,VIN=3.3V
Figure1Figure2Figure3Figure4Figure5Figure6Figure7Figure8Figure9Figure10Figure11Figure12
Thetypicalcharacteristicsaremeasuredwiththeinductors74477890033.3µH(highfrequency)orB82464G46.8µH(lowfrequency)fromEpcosandtherectifierdiodeSL22.
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MAXIMUMLOADCURRENT
vs
INPUTVOLTAGE
1.6
fS = 1.2 MHz1.41.2IOUT − Output Current (A)10.80.60.40.2
VOUT = 18.5 V02.53.03.54.04.55.0VIN − Input Voltage (V)
5.56.0G000
MAXIMUMLOADCURRENT
vs
INPUTVOLTAGE
1.6
fS = 1.2 MHz1.41.2
VOUT = 9 VVOUT = 9 VVOUT = 12 VIOUT − Output Current (A)10.80.60.4
VOUT = 12 VVOUT = 15 VVOUT = 15 V0.2
VOUT = 18.5 V02.53.03.54.04.55.0VIN − Input Voltage (V)
5.56.0G000
Figure1.EFFICIENCY
vs
LOADCURRENT
100908070fS= 1.2 MHzL= 3.3µHfS= 650 kHzL= 6.8 µHFigure2.EFFICIENCY
vs
LOADCURRENT
100908070fS= 1.2 MHzL= 3.3µHfS= 650 kHzL= 6.8 µHEfficiency - %Efficiency - %60504030201000
0.050.100.150.200.250.300.350.400.450.50
IOUT- Load current -A
VIN= 3.3 VVS= 12 V60504030201000
0.10
0.20
0.30
0.40
0.50
VIN= 3.3 VVS= 9 V0.60
0.700.80
IOUT- Load current -A
Figure3.Figure4.
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PWMSWITCHING
DISCONTINUOUSCONDUCTIONMODEPWMSWITCHING
CONTINUOUSCONDUCTIONMODE
VSW5 V/div
VSW5 V/div
VS_AC50 mV/div
VS_AC50 mV/div
VIN= 3.3 V
VS= 12 V/1 mAfS= 1.2 MHz
IL1A/div
VIN= 3.3 V
VS= 12 V/300 mAfS= 1.2 MHz
IL
200 mA/div
200 ns/div
200 ns/div
Figure5.
LOADTRANSIENTRESPONSEHIGHFREQUENCY(1.2MHz)
VIN= 3.3 VVS= 12 V
COUT= 20 µFL= 3.3µH
RCOMP= 51 kΩCCOMP= 1.6 nF
Figure6.
LOADTRANSIENTRESPONSELOWFREQUENCY(650kHz)
VIN= 3.3 VVS= 12 V
COUT= 20 µFL= 6.8µH
RCOMP= 24 kΩCCOMP= 3.3 nF
VS_AC200 mV/div
VS_AC200 mV/div
IOUT= 50 mA- 200 mA
IOUT= 50 mA- 200 mA
IOUT
100 mA/div
IOUT
100 mA/div
200µs/div
200µs/div
200µs/div
Figure7.Figure8.
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SOFT-START
21.8
SUPPLYCURRENT
vs
SUPPLYVOLTAGE
EN5V/div
ICC- Supply Current - mA1.61.41.210.80.60.40.2
SwitchingfS= 1.2 MHzL= 3.3µHVIN=3.3V
VS=12V/300mA
VS5V/div
IL1A/div
CSS=100nF
SwitchingfS= 650 kHzL= 6.8µHNot Switching2
2.5
3
3.544.55VCC- Supply Current - V
5.5
6
2ms/div
0
Figure9.FREQUENCY
vs
LOADCURRENT
160014001200FREQ = VINL= 3.3µH14001200
Figure10.FREQUENCY
vs
SUPPLYVOLTAGE
FREQ = VINL= 3.3µHfS- Frequency - kHz100080060040020000.0VIN= 3.3 VVS= 12 VFREQ = GNDL= 6.8µHfS- Frequency - kHz10008006004002000
FREQ = GNDL= 6.8µHVS= 12 V / 200 mA0.10.20.30.40.50.62.53.03.54.04.55.05.56.0
IOUT- Load current - mA
VCC- Supply Voltage - V
Figure11.Figure12.
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DETAILEDDESCRIPTION
VINVSENINFREQSWSSCurrent limitandSoft StarttOFFGeneratorBias Vref=1.238VUVLOThermal ShutdowntONPWMGeneratorGate Driver ofPowerTransistorCOMPGMAmplifierFBVrefPGNDFigure13.BlockDiagram
Theboostconverterisdesignedforoutputvoltagesupto18.5Vwithaswitchpeakcurrentlimitof2.0Aminimum.Thedevice,whichoperatesinacurrentmodeschemewithquasi-constantfrequency,isexternallycompensatedformaximumflexibilityandstability.Theswitchingfrequencyisselectablebetween650kHzand1.2MHzandtheminimuminputvoltageis2.3V.Tocontroltheinrushcurrentatstart-upasoft-startpinisavailable.
TPS61085boostconverter’snoveltopologyusingadaptiveoff-timeprovidessuperiorloadandlinetransientresponsesandoperatesalsooverawiderrangeofapplicationsthanconventionalconverters.
Theselectableswitchingfrequencyoffersthepossibilitytooptimizethedesigneitherfortheuseofsmallsizedcomponents(1.2MHz)orforhighersystemefficiency(650kHz).However,thefrequencychangesslightlybecausethevoltagedropacrosstherDS(on)hassomeinfluenceonthecurrentandvoltagemeasurementandthusontheon-time(theoff-timeremainsconstant).
Theconverteroperatesincontinuousconductionmode(CCM)assoonastheinputcurrentincreasesabovehalftheripplecurrentintheinductor,forlowerloadcurrentsitswitchesintodiscontinuousconductionmode(DCM).Iftheloadisfurtherreduced,thepartstartstoskippulsestomaintaintheoutputvoltage.
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DesignProcedure
Thefirststepinthedesignprocedureistoverifythatthemaximumpossibleoutputcurrentoftheboostconvertersupportsthespecificapplicationrequirements.Asimpleapproachistoestimatetheconverterefficiency,bytakingtheefficiencynumbersfromtheprovidedefficiencycurvesortouseaworstcaseassumptionfortheexpectedefficiency,e.g.90%.1.Dutycycle,D:
D=1-VIN×hVS
(1)
2.Maximumoutputcurrent,IOUT(max):
DIöæ
IOUT(max)=çILIM(min)-L÷×(1-D)
2øè3.Peakswitchcurrentinapplication,ISW(peak):
IDI
ISW(peak)=L+OUT
21-Dwiththeinductorpeak-to-peakripplecurrent,ΔIL
DIL=
VIN×DfS×L
(2)
(3)
(4)
and
VINVSILIM(min)fSLη
MinimuminputvoltageOutputvoltage
Converterswitchcurrentlimit(minimumswitchcurrentlimit=3.2A)Converterswitchingfrequency(typically1.2MHzor650kHz)Selectedinductorvalue
Estimatedconverterefficiency(pleaseusethenumberfromtheefficiencyplotsor90%asanestimation)
Thepeakswitchcurrentisthesteadystatepeakswitchcurrentthattheintegratedswitch,inductorandexternalSchottkydiodehastobeabletohandle.Thecalculationmustbedonefortheminimuminputvoltagewherethepeakswitchcurrentisthehighest.
Soft-start
Theboostconverterhasanadjustablesoft-starttopreventhighinrushcurrentduringstart-up.Tominimizetheinrushcurrentduringstart-upanexternalcapacitorconnectedtothesoft-startpinSSandchargedwithaconstantcurrent,isusedtoslowlyrampuptheinternalcurrentlimitoftheboostconverterwhenchargedwithaconstantcurrent.WhentheENpinispulledhigh,thesoft-startcapacitorCSSisimmediatelychargedto0.3V.Thecapacitoristhenchargedataconstantcurrentof10μAtypicallyuntiltheoutputoftheboostconverterVShasreacheditsPowerGoodthreshold(roughly98%ofVSnominalvalue).Duringthistime,theSSvoltagedirectlycontrolsthepeakinductorcurrent,startingwith0AatVSS=0.3VuptothefullcurrentlimitatVSS=0.8V.Themaximumloadcurrentisavailableafterthesoft-startiscompleted.Thelargerthecapacitortheslowertherampofthecurrentlimitandthelongerthesoft-starttime.A100nFcapacitorisusuallysufficientformostoftheapplications.WhentheENpinispulledlow,thesoft-startcapacitorisdischargedtoground.
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InductorSelection
TheTPS61085isdesignedtoworkwithawiderangeofinductors.ThemainparameterfortheinductorselectionisthesaturationcurrentoftheinductorwhichshouldbehigherthanthepeakswitchcurrentascalculatedintheDesignProceduresectionwithadditionalmargintocoverforheavyloadtransients.Analternative,moreconservative,istochooseaninductorwithasaturationcurrentatleastashighasthemaximumswitchcurrentlimitof3.2A.Theotherimportantparameteristheinductordcresistance.Usually,thelowerthedcresistancethehighertheefficiency.Itisimportanttonotethattheinductordcresistanceisnottheonlyparameterdeterminingtheefficiency.Especiallyforaboostconverterwheretheinductoristheenergystorageelement,thetypeandcorematerialoftheinductorinfluencestheefficiencyaswell.Athighswitchingfrequenciesof1.2MHzinductorcorelosses,proximityeffectsandskineffectsbecomemoreimportant.Usually,aninductorwithalargerformfactorgiveshigherefficiency.Theefficiencydifferencebetweendifferentinductorscanvarybetween2%to10%.FortheTPS61085,inductorvaluesbetween3μHand6μHareagoodchoicewithaswitchingfrequencyof1.2MHz,typically3.3μH.At650kHzinductorsbetween6μHand13μH,typically6.8μHarerecommended.PossibleinductorsareshowninTable1.
Typically,itisrecommendedthattheinductorcurrentrippleisbelow35%oftheaverageinductorcurrent.Therefore,thefollowingequationcanbeusedtocalculatetheinductorvalue,L:
æVöæV-VL=çIN÷×çSIN
èVSøèIOUT×fS
2
öæhö÷×ç÷øè0.35ø
(5)
with
VINVSIoutfSη
MinimuminputvoltageOutputvoltage
Maximumoutputcurrentintheapplication
Converterswitchingfrequency(typically1.2MHzor650kHz)
Estimatedconverterefficiency(pleaseusethenumberfromtheefficiencyplotsor90%asanestimation)
Table1.InductorSelection
L(μH)3.34.73.33.34.756.8106.810106.8
SUPPLIER
COMPONENT
CODE
1.2MHz
SumidaSumidaSumidaSumidaWürthElektronik
CoilcraftSumidaCoilcraftSumidaSumidaWürthElektronik
Sumida
CDH38D09CDPH36D13CDPH4D19FCDRH6D127447785004MSS7341
650kHzCDP14D19LPS4414CDRH6D12/LDCDR6D23744778910CDRH6D26HP
5.2x5.2x24.3×4.3×1.46.7x6.7x1.55×5×2.47.3×7.3×3.27x7x2.8
50380951335152
11.21.251.752.22.9
4x4x15×5×1.55.2x5.2x26.7x6.7x1.55.9×6.2×3.37.3×7.3×4.1
24015533626024
1.251.361.52.22.52.9
SIZE(L×W×Hmm)
DCRTYP(mΩ)
Isat(A)
RectifierDiodeSelection
Toachievehighefficiency,aSchottkytypeshouldbeusedfortherectifierdiode.Thereversevoltageratingshouldbehigherthanthemaximumoutputvoltageoftheconverter.TheaveragedrectifiedforwardcurrentIavg,theSchottkydiodeneedstoberatedfor,isequaltotheoutputcurrentIOUT:
Iavg=IOUT
(6)
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UsuallyaSchottkydiodewith2Amaximumaveragerectifiedforwardcurrentratingissufficientformostapplications.TheSchottkyrectifiercanbeselectedwithlowerforwardcurrentcapabilitydependingontheoutputcurrentIoutbuthastobeabletodissipatethepower.Thedissipatedpower,PD,istheaveragerectifiedforwardcurrenttimesthediodeforwardvoltage,Vforward.
PD=Iavg×Vforward
(7)
Typicallythediodeshouldbeabletodissipatearound500mWdependingontheloadcurrentandforwardvoltage.
Table2.RectifierDiodeSelection
CURRENTRATINGIavg750mA1A1A1A1A
Vr20V20V20V20V20V
Vforward/Iavg0.425V/750mA0.39V/1A0.52V/1A0.5V/1A0.44V/1A
SUPPLIERFairchildSemiconductor
NXP
VishaySemiconductorVishaySemiconductorVishaySemiconductor
COMPONENT
CODEFYV0704SPMEG2010AEH
B120SS12MSS1P2L
PACKAGETYPESOT23SOD123SMASMAμ-SMP(LowProfile)
SettingtheOutputVoltage
Theoutputvoltageissetbyanexternalresistordivider.Typically,aminimumcurrentof50μAflowingthroughthefeedbackdividergivesgoodaccuracyandnoisecovering.Astandardlowsideresistorof18kΩistypicallyselected.Theresistorsarethencalculatedas:
VSR2=
VFB
»18kW70mA
æVö
R1=R2×çS-1÷
èVFBø
VFB
R1VFB=1.238V
R2(8)
Compensation(COMP)
TheregulatorloopcanbecompensatedbyadjustingtheexternalcomponentsconnectedtotheCOMPpin.The
COMPpinistheoutputoftheinternaltransconductanceerroramplifier.
StandardvaluesofRCOMP=13kΩandCCOMP=3.3nFwillworkforthemajorityoftheapplications.
SeeTable3fordedicatedcompensationnetworksgivinganimprovedloadtransientresponse.ThefollowingequationscanbeusedtocalculateRCOMPandCCOMP:
110×VIN×VS×COUTVs×COUT
RCOMP=CCOMP=
L×IOUT7.5×IOUT×RCOMP
(9)with
VINVSCoutLIOUT
MinimuminputvoltageOutputvoltageOutputcapacitance
Inductorvalue,e.g.3.3μHor6.8μHMaximumoutputcurrentintheapplication
MakesurethatRCOMP<120kΩandCCOMP>820pF,independentoftheresultsoftheaboveformulas.
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Table3.RecommendedCompensationNetworkValuesatHigh/LowFrequency
FREQUENCY
L
VS15V
High(1.2MHz)
3.3µH
12V9V15V
Low(650kHz)
6.8µH
12V9V
VIN±20%
5V3.3V5V3.3V5V3.3V5V3.3V5V3.3V5V3.3V
RCOMP82kΩ75kΩ51kΩ47kΩ30kΩ27kΩ43kΩ39kΩ27kΩ24kΩ15kΩ13kΩ
CCOMP1.1nF1.6nF1.1nF1.6nF1.1nF1.6nF2.2nF3.3nF2.2nF3.3nF2.2nF3.3nF
UsedIOUT
0.7A0.5A0.9A0.6A1.2A0.8A0.7A0.5A0.9A0.6A1.2A0.8A
Table3givesconservativeRCOMPandCCOMPvaluesforcertaininductors,inputandoutputvoltagesprovidingaverystablesystem.Forafasterresponsetime,ahigherRCOMPvaluecanbeusedtoenlargethebandwidth,aswellasaslightlylowervalueofCCOMPtokeepenoughphasemargin.TheseadjustmentsshouldbeperformedinparallelwiththeloadtransientresponsemonitoringofTPS61087.
InputCapacitorSelection
ForgoodinputvoltagefilteringlowESRceramiccapacitorsarerecommended.TPS61085hasananaloginputIN.Therefore,a1μFbypassishighlyrecommendedascloseaspossibletotheICfromINtoGND.
One10μFceramicinputcapacitorsaresufficientformostoftheapplications.Forbetterinputvoltagefilteringthisvaluecanbeincreased.RefertoTable4andtypicalapplicationsforinputcapacitorrecommendations.
OutputCapacitorSelection
ForbestoutputvoltagefilteringalowESRoutputcapacitorlikeceramiccapcaitorisrecommended.Two10μFceramicoutputcapacitors(orone22μF)workformostoftheapplications.Highercapacitorvaluescanbeusedtoimprovetheloadtransientresponse.RefertoTable4fortheselectionoftheoutputcapacitor.
Table4.RectifierInputandOutputCapacitorSelection
CAPACITOR
CININbypassCOUT
10μF/12061μF/060310μF/1206
VOLTAGERATING
16V16V25V
SUPPLIERTaiyoYudenTaiyoYudenTaiyoYuden
COMPONENTCODEEMK212BJ106KGEMK107BJ105KATMK316BJ106KL
Tocalculatetheoutputvoltageripple,thefollowingequationcanbeused:
V-VINIOUT
DVC_ESR=IL(peak)×RC_ESRDVC=S×
VS×fSCOUTwith
ΔVCVSVINfSIoutΔVC_ESRISWPEAKRC_ESR
Outputvoltagerippledependentonoutputcapacitance,outputcurrentandswitchingfrequencyOutputvoltage
Minimuminputvoltageofboostconverter
Converterswitchingfrequency(typically1.2MHzor650kHz)Outputcapacitance
OutputvoltagerippleduetooutputcapacitorsESR(equivalentseriesresistance)InductorpeakswitchcurrentintheapplicationOutputcapacitorsequivalentseriesresistance(ESR)
(10)
ΔVC_ESRcanbeneglectedinmanycasessinceceramiccapacitorsprovidelowESR.
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FrequencySelectPin(FREQ)
ThefrequencyselectpinFREQallowstosettheswitchingfrequencyofthedeviceto650kHz(FREQ=low)or1.2MHz(FREQ=high).Higherswitchingfrequencyimprovesloadtransientresponsebutreducesslightlytheefficiency.Theotherbenefitsofhigherswitchingfrequencyarealoweroutputripplevoltage.Theuseofthe1.2MHzswitchingfrequencyisrecommendedunlesslightloadefficiencyisamajorconcern.
UndervoltageLockout(UVLO)
Toavoidmis-operationofthedeviceatlowinputvoltagesanundervoltagelockoutisincludedthatdisablesthedevice,iftheinputvoltagefallsbelow2.2V.
ThermalShutdown
Athermalshutdownisimplementedtopreventdamagesduetoexcessiveheatandpowerdissipation.Typicallythethermalshutdownthresholdhappensatajunctiontemperatureof150°C.Whenthethermalshutdownistriggeredthedevicestopsswitchinguntilthetemperaturefallsbelowtypically136°C.Thenthedevicestartsswitchingagain.
OvervoltagePrevention
IfovervoltageisdetectedontheFBpin(typically3%abovethenominalvalueof1.238V)thepartstopsswitchingimmediatelyuntilthevoltageonthispindropstoitsnominalvalue.Thispreventsovervoltageontheoutputandsecuresthecircuitsconnectedtotheoutputfromexcessiveovervoltage.
APPLICATIONINFORMATION
GeneralBoostApplicationCircuits
L3.3µH
VIN3.3 V ±20%CBY1µF16 V6INSW5DPMEG2010AEHR1158 kΩR218.2 kΩRCOMP47 kΩCSS100nFCCOMP1.6 nFVS12 V/600 mAmax
CIN10µF16 V3ENFB2COUT2* 10 µF25 V7FREQCOMP14GNDTPS61085SS8Figure14.TypicalApplication,3.3Vto12V(fS=1.2MHz)
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TPS61085
SLVS859A–JUNE2008–REVISEDAPRIL2012
www.ti.com
L6.8µH
VIN3.3 V ±20%CBY1µF16 V6INSW5DPMEG2010AEHR1158 kΩR218.2 kΩRCOMP24 kΩCSS100 nFCCOMP3.3 nFVS12 V/600 mAmax
CIN10µF16 V3ENFB2COUT2* 10 µF25 V7FREQCOMP14GNDTPS61085SS8Figure15.TypicalApplication,3.3Vto12V(fS=650kHz)
L3.3µH
VIN3.3 V ±20%CBY1µF16 V6INSW5DPMEG2010AEHR1113 kΩR218 kΩRCOMP27 kΩCSS100 nFCCOMP1.6 nFVS9 V/800 mAmax
CIN10µF16 V3ENFB2COUT2* 10 µF25 V7FREQCOMP14GNDTPS61085SS8Figure16.TypicalApplication,3.3Vto9V(fS=1.2MHz)
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TPS61085
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SLVS859A–JUNE2008–REVISEDAPRIL2012
L6.8µH
VIN3.3 V ±20%CBY1µF16 V6INSW5DPMEG2010AEHR1113 kΩR218 kΩRCOMP13 kΩCSS100 nFCCOMP3.3 nFVS9 V/800 mAmax
CIN10 µF16 V3ENFB2COUT2* 10µF25 V7FREQCOMP14GNDTPS61085SS8Figure17.TypicalApplication,3.3Vto9V(fS=650kHz)
RISO10 kΩ
L6.8µHVIN3.3 V ±20%CIN10µF16 VCBY1µF/16 V6374DPMEG2010AEHBC857CVS12 V/300 mAR1158 kΩR218.2 kΩINENFREQGNDTPS61085SWFBCOMPSS5218CISO1µF/ 25 VCOUT2*10 µF25 VRCOMP24 kΩCSS100nFCCOMP3.3 nFFigure18.TypicalApplicationwithExternalLoadDisconnectSwitch
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TPS61085
SLVS859A–JUNE2008–REVISEDAPRIL2012
www.ti.com
TFTLCDApplicationCircuit
C4100nF/50VC3100nF50VD3BAT54S3*VSD4BAT54SD5BAT54SD6BAT54SC7470nF50VC6470nF50V2*VSD8BZX84C20VT2BC850BVGH
20V/20mA
VGL-7 V/ 20 mAC11µF/35VT1BC857B-VSD2BAT54SR1013kΩC2R87 kΩ470 nF25 VD1BZX84C7V5C81µF35VC5100nF50VD7BAT54SL3.3µHVIN3.3V±20%CBY1µF16V63VINENSWFB52DPMEG2010AEHR1113kΩR218 kΩRCOMP27 kΩCSS100nFCCOMP1.6nFVS9V/500mACIN10µF16VCOUT2*10µF25V7FREQCOMP14GNDTPS61085SS8Figure19.TypicalApplication3.3Vto9V(fS=1.2MHz)forTFTLCDwithExternalChargePumps(VGH,
VGL)
WHITELEDApplicationCircuits
L6.8 µH
CBY1 µF/ 16 V6CIN10 µF/16 V3INENFB74FREQPGNDTPS61085COMPSS218CSS100 nFRLIMIT110ΩRCOMP24 kΩCCOMP3.3 nFRSENSE15ΩSW5optionalDSL22DZBZX84C 18 V3S3PwLEDLW E67CVS500 mAVIN5 V ± 20%COUT2* 10 µF/25 VFigure20.SimpleApplication(3.3Vinput-fsw=650kHz)forwLEDSupply(3S3P)(withOptional
ClampingZenerDiode)
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SLVS859A–JUNE2008–REVISEDAPRIL2012
L6.8 µH
CBY1 µF/ 16 V6CIN10 µF/16 V3INENFB7PWM100 Hz to 500 Hz4FREQPGNDTPS61085COMPSS218CSS100 nFRLIMIT110ΩRCOMP24 kΩCCOMP3.3 nFRSENSE15ΩSW5optionalDSL22DZBZX84C 18 V3S3PwLEDLW E67CVS500 mAVIN5 V ± 20%COUT2* 10 µF/25 VFigure21.SimpleApplication(3.3Vinput-fsw=650kHz)forwLEDSupply(3S3P)withAdjustableBrightnessControlusingaPWMSignalontheEnablePin(withOptionalClampingZenerDiode)
L6.8 µH
CBY1 µF/ 16 V6CIN10 µF/16 V3INENFB74FREQPGNDTPS61085COMPSS218RCOMP24 kΩCCOMP3.3 nFR2127 kΩR1optional5DSL22DZBZX84C 18 V3S3PwLEDLW E67CVS500 mAVIN5 V ± 20%SWRLIMIT110ΩRSENSE15ΩCOUT2* 10 µF/25 V180 kΩCSS100 nFAnalog Brightness Control3.3 V ~ wLED off0 V ~ lLED= 30 mA(each string)PWM SignalCan be used swinging from 0 V to 3.3 VFigure22.SimpleApplication(3.3Vinput-fsw=650kHz)forwLEDSupply(3S3P)withAdjustableBrightnessControlusinganAnalogSignalontheFeedbackPin(withOptionalClampingZenerDiode)
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TPS61085
SLVS859A–JUNE2008–REVISEDAPRIL2012
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REVISIONHISTORY
ChangesfromOriginal(June2008)toRevisionA•••••••••••
Page
ChangedthecircuitillustrationvalueofCCOMPFrom:1.6nFTo:1.1nF..............................................................................1DeletedLeadTemperaturefromtheAbsMaxtable.............................................................................................................2Addedaconditionsstatementandtwonewgraphs(MaxLoadCurrentvsInputVoltage)totheTypical
Characteristicsgraphs..........................................................................................................................................................5AddedthreeparagraphsoftexttotheDetailedDescription-followingtheBlockDiagram(Figure13)..............................8ChangedtheDesignProcuduresstep3detailsfollowingEquation4..................................................................................9ChangedtextintheInductorSelectionsection\"inductorcurrentrippleisbelow20%\"to\"inductorcurrentrippleis
below35%\".........................................................................................................................................................................10ChangedEquation8...........................................................................................................................................................11AddedUsedIOUTtoTable3................................................................................................................................................12AddedEquation10.............................................................................................................................................................12ChangedFigure14toFigure18.........................................................................................................................................13ChangedtheWhiteLEDApplicationsoptionalZenerconnectionforFigure20toFigure22............................................16
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PACKAGE OPTION ADDENDUM
www.ti.com
18-Apr-2012
PACKAGING INFORMATION
Orderable DeviceTPS61085DGKRTPS61085DGKRG4TPS61085DGKTTPS61085DGKTG4TPS61085PWTPS61085PWG4TPS61085PWRTPS61085PWRG4
(1)
Status
(1)
Package TypePackage
Drawing
MSOPMSOPMSOPMSOPTSSOPTSSOPTSSOPTSSOP
DGKDGKDGKDGKPWPWPWPW
Pins88888888
Package Qty
2500250025025015015020002000
Eco Plan
(2)
Lead/Ball Finish
MSL Peak Temp
(3)
Samples(Requires Login)
ACTIVEACTIVEACTIVEACTIVEACTIVEACTIVEACTIVEACTIVE
Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)Green (RoHS& no Sb/Br)
CU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIMCU NIPDAULevel-1-260C-UNLIM
The marketing status values are defined as follows:ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.PREVIEW: Device has been announced but is not in production. Samples may or may not be available.OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availabilityinformation and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms \"Lead-Free\" or \"Pb-Free\" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement thatlead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used betweenthe die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines \"Green\" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weightin homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
18-Apr-2012
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on informationprovided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken andcontinues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF TPS61085 :
•Automotive: TPS61085-Q1
NOTE: Qualified Version Definitions:
•Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects
Addendum-Page 2
PACKAGEMATERIALSINFORMATION
www.ti.com
17-Apr-2012
TAPEANDREELINFORMATION
*Alldimensionsarenominal
Device
PackagePackagePinsTypeDrawingMSOPMSOPTSSOP
DGKDGKPW
888
SPQ
ReelReelA0DiameterWidth(mm)(mm)W1(mm)330.0180.0330.0
12.412.412.4
5.35.37.0
B0(mm)3.43.43.6
K0(mm)1.41.41.6
P1(mm)8.08.08.0
WPin1(mm)Quadrant12.012.012.0
Q1Q1Q1
TPS61085DGKRTPS61085DGKTTPS61085PWR
25002502000
PackMaterials-Page1
PACKAGEMATERIALSINFORMATION
www.ti.com
17-Apr-2012
*Alldimensionsarenominal
DeviceTPS61085DGKRTPS61085DGKTTPS61085PWR
PackageType
MSOPMSOPTSSOP
PackageDrawing
DGKDGKPW
Pins888
SPQ25002502000
Length(mm)
346.0210.0346.0
Width(mm)346.0185.0346.0
Height(mm)
29.035.029.0
PackMaterials-Page2
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