TPS63030中文资料(14)

元器件交易网SLVS696–

APPLICATIONINFORMATION

DESIGNPROCEDURE

TheTPS6303xdc/dcconvertersareintendedforsystemspoweredbyone-cellLi-IonorLi-Polymerbatterywithatypicalvoltagebetween2.3Vand4.5V.TheycanalsobeusedinsystemspoweredbyadoubleortriplecellAlkaline,NiCd,orNiMHbatterywithatypicalterminalvoltagebetween1.8Vand5.5V.Additionally,anyothervoltagesourcewithatypicaloutputvoltagebetween1.8Vand5.5VcanpowersystemswheretheTPS6303xisused.

PROGRAMMINGTHEOUTPUTVOLTAGE

WithintheTPS6303Xfamilytherearefixedandadjustableoutputvoltageversionsavailable.Toproperlyconfigurethefixedoutputvoltagedevices,theFBpinisusedtosensetheoutputvoltage.ThismeansthatitmustbeconnecteddirectlytoVOUT.Attheadjustableoutputvoltageversions,anexternalresistordividerisusedtoadjusttheoutputvoltage.TheresistordividermustbeconnectedbetweenVOUT,FBandGND.Whentheoutputvoltageisregulatedproperly,thetypicalvalueofthevoltageattheFBpinis500mV.Themaximumrecommendedvaluefortheoutputvoltageis5.5V.Thecurrentthroughtheresistivedividershouldbeabout100timesgreaterthanthecurrentintotheFBpin.ThetypicalcurrentintotheFBpinis0.01µA,andthevoltageacrosstheresistorbetweenFBandGND,R2,istypically500mV.Basedonthosetwovalues,therecommendedvalueforR2shouldbelowerthan500k ,inordertosetthedividercurrentat1µAorhigher.Itisrecommendedtokeepthevalueforthisresistorintherangeof200k .Fromthat,thevalueoftheresistorconnectedbetweenVOUTandFB,R1,dependingontheneededoutputvoltage(VOUT),canbecalculatedusingEquation1R1+R2

ǒ

VOUTVFB

*1

ǔ

(1)

L1

Figure21.TypicalApplicationCircuitforAdjustableOutputVoltageOption

INDUCTORSELECTION

ToproperlyconfiguretheTPS6303Xdevices,aninductormustbeconnectedbetweenpinL1andpinL2.ToestimatetheinductancevalueEquation2andEquation3canbeused.

μs

L1=(VIN1-VOUT)×0.5×

A(2)

μs

L2=VOUT×0.5×

A(3)InEquation2theminimuminductancevalue,L1forstepdownmodeoperationiscalculated.VIN1isthe

voltage.InEquation3theminimuminductance,L2,forboostmodeoperationiscalculated.TherecommendedminimumiseitherL1orL2whicheverishigher.Asanexample,asuitableinductorforgenerating3.3VfromaLi-Ionbatterywithabatteryvoltagerangefrom2.5Vupto4.2Vis2.2µH.Therecommendedinductorvaluerangeisbetween1.5µHand4.7µH.Ingeneral,thismeansthatathighvoltageconversionrates,higherinductorvaluesofferbetterperformance.