CMOS与双极型LDO的直流性能比较时，在“差”（VIN=额定VOUT）的操作模式
Moreandmore,batteryoperatedsystemsarerequiringlower
terminalvoltagestopowerinternalcircuits.Multi-celldesignsare
rapidlymigratingtosingle-cellarchitecturestoreducesystemcost.
Aprimeexampleofthissystemtypeisdigitalcameras,whichoften
useasingle-cell3.6VLi-Ionbatteryfortheirpowersource.Digital
camerascontainhigh-speedmemoryICs,whichrequiretight
voltageregulationatmoderateloadstomeettherequiredtiming
parametersofthesystem.Precisionlowdropout(LDO)regulator
devicescanbeusedtomeettheserequirementsbutindoingso,
theLDOregulatorsmustbeabletosuccessfullyoperateinthe
‘dropout’modeasthebatterydischarges.Dropoutmodeisentered
whentheinputvoltage(fromthebatterysource)isequaltothe
“nominaloutputvoltage”oftheLDO;forexamplea3.3VLDO
entersdropoutmodewhenitsinputvoltageattheV
IN
pinisequal
to3.3V.MinimaloutputvoltagedroopandminimalLDOpower
dissipationarecriticaltomeetingvarioussystemperformance
parametersandextendingthelifeofthebattery.AN776DCPerformanceComparisonsofCMOSvs.BipolarLDOswhenOperatingin"Dropout"(VIN=NominalVOUT)ModeAuthor:PatrickMaresca,BACKGROUNDINFORMATION:MicrochipTechnology,Inc.CMOSvs.BIPOLARARCHITECTUREFigures1Aand1BcomparetheblockdiagramforacommonbipolarregulatorwiththatofanequivalentregulatorfabricatedinINTRODUCTION
