300mA的超低噪声小封装超高速CMOS LDO稳压器LP3984.docx

300mA的超低噪声小封装超高速CMOS LDO稳压器LP3984.docx

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300mA的超低噪声小封装超高速CMOSLDO稳压器LP3984

300mA,Ultra-lownoise,SmallPackage

Ultra-FastCMOSLDORegulator

GeneralDescription

TheLP3984isdesignedforportableRFandwirelessapplicationswithdemandingperformanceandspacerequirements.TheLP3984performanceisoptimizedforbattery-poweredsystemstodeliverultralownoiseandlowquiescentcurrent.Anoisebypasspinisavailableforfurtherreductionofoutputnoise.Regulatorgroundcurrentincreasesonlyslightlyindropout,furtherprolongingthebatterylife.TheLP3984alsoworkswithlow-ESRceramiccapacitors,reducingtheamountofboardspacenecessaryforpowerapplications,criticalinhand-heldwirelessdevices.TheLP3984consumeslessthan0.01µAinshutdownmodeandhasfastturn-ontimelessthan50µs.Theotherfeaturesincludeultralowdropoutvoltage,highoutputaccuracy,currentlimitingprotection,andhighripplerejectionratio.Itisavailableinthe5-leadofSOT23-5packages.

OrderingInformation

LP3984□□□□□

F:

Pb-Free

PackageType

B5:

SOT23-5

OutputVoltageType

12:

1.2V

13:

1.3V

15:

1.5V

18:

1.8V

25:

2.5V

28:

2.8V

2H:

2.85V

30:

3.0V

33:

3.3V

Features

◆Ultra-Low-NoiseforRFApplication

◆2V-6.5VInputVoltageRange

◆LowDropout:

200mV@300mA

◆1.2V,1.3V,1.5V,1.8V,2.5V,2.8V3.0Vand3.3VFixed

◆300mAOutputCurrent,550mAPeakCurrent

◆HighPSSR:

-73dBat1KHz

◆<0.01uAStandbyCurrentWhenShutdown

◆AvailableinSOT23-5Package

◆TTL-Logic-ControlledShutdownInput

◆Ultra-FastResponseinLine/Loadtransient

◆CurrentLimitingandThermalShutdownProtection

◆Quickstart-up（typically50uS）

TypicalApplicationCircuit

Applications

✧PortableMediaPlayers/MP3players

✧CellularandSmartmobilephone

✧LCD

✧DSCSensor

✧WirelessCard

PinConfigurations

SOT23-5

MarkingInformation

Device

Marking

Package

Shipping

LP3984

XXXX

SOT23-5

3K/REEL

FunctionalPinDescription

Pinnumber

PinName

PinFunction

1

VIN

PowerInputVoltage.

2

GND

Ground.

3

EN

ChipEnable（ActiveHigh）.Notethatthispinishighimpedance.Thereshouldbeapulllow100kΩresistorconnectedtoGNDwhenthecontrolsignalisfloating.

4

BP

ReferenceNoiseBypass.

5

VOUT

OutputVoltage.

FunctionBlockDiagram

AbsoluteMaximumRatings

SupplyInputVoltage----------------------------------------------------------------------------------------------------------6.5V

PowerDissipation,PD@TA=25°C

SOT23-5-------------------------------------------------------------------------------------------------------------------400mW

PackageThermalResistance

SOT23-5,θJA----------------------------------------------------------------------------------------------------------250°C/W

LeadTemperature（Soldering,10sec.）-----------------------------------------------------------------------------260°C

StorageTemperatureRange-----------------------------------------------------------------------------−65°Cto150°C

ESDSusceptibility

HBM（HumanBodyMode）------------------------------------------------------------------------------------------------2kVMM（Machine-Mode）--------------------------------------------------------------------------------------------------------200V

RecommendedOperatingConditions

SupplyInputVoltage----------------------------------------------------------------------------------------------2.5Vto5.5V

ENInputVoltage-----------------------------------------------------------------------------------------------------0Vto5.5V

OperationJunctionTemperatureRange----------------------------------------------------------------−40°Cto125°C

OperationAmbientTemperatureRange-------------------------------------------------------------------−40°Cto85°C

ElectricalCharacteristics

（VIN=VOUT+1V,CIN=COUT=1µF,CBP=22nF,TA=25°C,unlessotherwisespecified）

Parameter

Symbol

TestConditions

Min

Typ.

Max

Units

OutputVoltageAccuracy

ΔVOUT

IOUT=1mA

−2

--

+2

%

OutputLoadingCurrent

ILOAD

VEN=VIN,VIN>2.5V

300

mA

CurrentLimit

ILIM

RLOAD=1Ω

360

400

mA

QuiescentCurrent

IQ

VEN≥1.2V,IOUT=0mA

75

130

μA

DropoutVoltage

VDROP

IOUT=200mA,VOUT>2.8V

120

150

mV

IOUT=300mA,VOUT>2.8V

200

260

LineRegulation

ΔVLINE

VIN=（VOUT+1V）to5.5V,IOUT=1mA

0.3

%

LoadRegulation

ΔLOAD

1mA

0.6

%

StandbyCurrent

ISTBY

VEN=GND,Shutdown

0.01

1

μA

ENInputBiasCurrent

IIBSD

VEN=GNDorVIN

0.1

100

nA

ENThreshold

Logic-LowVoltage

VIL

VIN=3Vto5.5V,Shutdown

0.4

V

Logic-HighVoltage

VIH

VIN=3Vto5.5V,Start-Up

1.4

OutputNoiseVoltage

10Hzto100kHz,IOUT=200mACOUT=1µF

100

uVRMS

PowerSupply

f=100Hz

PSRR

−76

dB

RejectionRate

f=10kHz

COUT=1µF,

IOUT=10mA

−68

ThermalShutdownTemperature

TSD

165

°C

TypicalOperatingCharacteristics

ILoad=200mA

ApplicationsInformation

Likeanylow-dropoutregulator,theexternalcapacitorsusedwiththeLP3984mustbecarefullyselectedforregulatorstabilityandperformance.Usingacapacitorwhosevalueis>1µFontheLP3984inputandtheamountofcapacitancecanbeincreasedwithoutlimit.Theinputcapacitormustbelocatedadistanceofnotmorethan0.5inchfromtheinputpinoftheICandreturnedtoacleananalogground.Anygoodqualityceramicortantalumcanbeusedforthiscapacitor.ThecapacitorwithlargervalueandlowerESR（equivalentseriesresistance）providesbetterPSRRandline-transientresponse.TheoutputcapacitormustmeetbothrequirementsforminimumamountofcapacitanceandESRinallLDOsapplication.TheLP3984isdesignedspecificallytoworkwithlowESRceramicoutputcapacitorinspace-savingandperformanceconsideration.Usingaceramiccapacitorwhosevalueisatleast1µFwithESRis>25mΩontheLP3984outputensuresstability.TheLP3984stillworkswellwithoutputcapacitorofothertypesduetothewidestableESRrange.Figure1showsthecurvesofallowableESRrangeasafunctionofloadcurrentforvariousoutputcapacitorvalues.Outputcapacitoroflargercapacitancecanreducenoiseandimproveloadtransientresponse,stability,andPSRR.Theoutputcapacitorshouldbelocatednotmorethan0.5inchfromtheVOUTpinoftheLP3984andreturnedtoacleananalogground.

Start-upFunctionEnableFunction

TheLP3984featuresanLDOregulatorenable/disablefunction.ToassuretheLDOregulatorwillswitchon,theENturnoncontrollevelmustbegreaterthan1.4volts.TheLDOregulatorwillgointotheshutdownmodewhenthevoltageontheENpinfallsbelow0.4volts.Fortoprotectingthesystem,theLP3984haveaquick-dischargefunction.Iftheenablefunctionisnotneededinaspecificapplication,itmaybetiedtoVINtokeeptheLDOregulatorinacontinuouslyonstate.

BypassCapacitorandLowNoise

Connectinga22nFbetweentheBPpinandGNDpinsignificantlyreducesnoiseontheregulatoroutput,itiscriticalthatthecapacitorconnectionbetweentheBPpinandGNDpinbedirectandPCBtracesshouldbeasshortaspossible.ThereisarelationshipbetweenthebypasscapacitorvalueandtheLDOregulatorturnontime.DCleakageonthispincanaffecttheLDOregulatoroutputnoiseandvoltageregulationperformance.

ThermalConsiderations

ThermalprotectionlimitspowerdissipationinLP3984.Whentheoperationjunctiontemperatureexceeds165°C,theOTPcircuitstartsthethermalshutdownfunctionturnthepasselementoff.Thepasselementturnsonagainafterthejunctiontemperaturecoolsby30°C.Forcontinueoperation,donotexceedabsolutemaximumoperationjunctiontemperature125°C.

Thepowerdissipationdefinitionindeviceis:

PD=（VIN−VOUT）xIOUT+VINxIQ

ThemaximumpowerdissipationdependsonthethermalresistanceofICpackage,PCBlayout,therateofsurroundingsairflowandtemperaturedifferencebetweenjunctiontoambient.

Themaximumpowerdissipationcanbecalculatedbyfollowingformula:

PD（MAX）=（TJ（MAX）−TA）/θJA

Where

TJ（MAX）isthemaximumoperationjunctiontemperature125°C,TAistheambienttemperatureandtheθJAisthejunctiontoambientthermalresistance.ForrecommendedoperatingconditionsspecificationofLP3984,where

TJ（MAX）isthemaximumjunctiontemperatureofthedie（125°C）andTAisthemaximumambienttemperature.Thejunctiontoambientthermalresistance（θJAislayoutdependent）forSOT23-5packageis250°C/W.

PD（MAX）=（125°C−25°C）/250=400mW（SOT23-5）PD（MAX）=（125°C−25°C）/165=606mW（withPCBPAD）

ThemaximumpowerdissipationdependsonoperatingambienttemperatureforfixedTJ（MAX）andthermalresistanceθJA.

PackagingInformation