LM2704MF-ADJ资料
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LM2704
MicropowerStep-upDC/DCConverterwith550mAPeak
CurrentLimit
GeneralDescription
TheLM2704isamicropowerstep-upDC/DCinasmall
5-leadSOT-23package.Acurrentlimited,fixedoff-time
controlschemeconservesoperatingcurrentresultinginhigh
efficiencyoverawiderangeofloadconditions.The21V
switchallowsforoutputvoltagesashighas20V.Thelow
400nsoff-timepermitstheuseoftiny,lowprofileinductors
andcapacitorstominimizefootprintandcostinspace-
consciousportableapplications.TheLM2704isidealfor
LCDpanelsrequiringlowcurrentandhighefficiencyaswell
aswhiteLEDapplicationsforcellularphoneback-lighting.
TheLM2704candriveupto8whiteLEDsfromasingle
Li-Ionbattery.Features
n550mA,0.7Ω,internalswitch
nUsessmallsurfacemountcomponents
nAdjustableoutputvoltageupto20V
n2.2Vto7Vinputrange
nInputundervoltagelockout
n0.01µAshutdowncurrent
nSmall5-LeadSOT-23package
Applications
nLCDBiasSupplies
nWhiteLEDBack-Lighting
nHandheldDevices
nDigitalCameras
nPortableApplications
TypicalApplicationCircuit
20031501
FIGURE1.Typical20VApplicationApril2003LM2704
Micropower
Step-up
DC/DC
Converter
with
550mA
Peak
Current
Limit
©2003NationalSemiconductorCorporationDS200315www.national.com元器件交易网www.cecb2b.comConnectionDiagram
TopView
20031502SOT23-5
TJmax=125˚C,θJA=220˚C/W(Note2)
OrderingInformation
OrderNumberPackageTypeNSCPackageDrawingTopMarkSuppliedAs
LM2704MF-ADJSOT23-5MA05BS28B1000Units,TapeandReel
LM2704MFX-ADJSOT23-5MA05BS28B3000Units,TapeandReel
PinDescription/Functions
PinNameFunction
1SWPowerSwitchinput.
2GNDGround.
3FBOutputvoltagefeedbackinput.
4SHDNShutdowncontrolinput,activelow.
5VINAnalogandPowerinput.
SW(Pin1):SwitchPin.Thisisthedrainoftheinternal
NMOSpowerswitch.Minimizethemetaltraceareacon-
nectedtothispintominimizeEMI.
GND(Pin2):GroundPin.Tiedirectlytogroundplane.
FB(Pin3):FeedbackPin.Settheoutputvoltagebyselecting
valuesforR1andR2using:ConnectthegroundofthefeedbacknetworktoanAGND
planewhichshouldbetieddirectlytotheGNDpin.
SHDN(Pin4):ShutdownPin.Theshutdownpinisanactive
lowcontrol.Tiethispinabove1.1Vtoenablethedevice.Tie
thispinbelow0.3Vtoturnoffthedevice.
VIN(Pin5):InputSupplyPin.Bypassthispinwithacapacitor
asclosetothedeviceaspossible.LM2704
www.national.com2元器件交易网www.cecb2b.comAbsoluteMaximumRatings(Note1)
IfMilitary/Aerospacespecifieddevicesarerequired,
pleasecontacttheNationalSemiconductorSalesOffice/
Distributorsforavailabilityandspecifications.
VIN7.5V
SWVoltage21V
FBVoltage2V
SHDNVoltage7.5V
MaximumJunctionTemp.TJ(Note2)150˚C
LeadTemperature
(Soldering10sec.)300˚C
VaporPhase
(60sec.)215˚CInfrared
(15sec.)220˚C
ESDRatings(Note3)
HumanBodyModel
MachineModel(Note4)2kV
200V
OperatingConditions
JunctionTemperature
(Note5)−40˚Cto+125˚C
SupplyVoltage2.2Vto7V
SWVoltageMax.20.5V
ElectricalCharacteristics(Note5)
SpecificationsinstandardtypefaceareforTJ=25˚CandthoseinboldfacetypeapplyoverthefullOperatingTemperature
Range(TJ=−40˚Cto+125˚C).Unlessotherwisespecified.VIN=2.2V.
SymbolParameterConditionsMin
(Note5)Typ
(Note6)Max
(Note5)Units
IQDeviceDisabledFB=1.3V4070
µADeviceEnabledFB=1.2V235300
ShutdownSHDN=0V0.012.5
VFBFeedbackTripPoint1.1891.2371.269V
ICLSwitchCurrentLimit490
420550610
620mA
IBFBPinBiasCurrentFB=1.23V(Note7)30120nA
VINInputVoltageRange2.27.0V
RDSONSwitchRDSON0.71.6Ω
TOFFSwitchOffTime400ns
ISDSHDNPinCurrentSHDN=VIN,TJ=25˚C080
nASHDN=VIN,TJ=125˚C15
SHDN=GND0
ILSwitchLeakageCurrentVSW=20V0.055µA
UVPInputUndervoltageLockoutON/OFFThreshold1.8V
VFBHysteresisFeedbackHysteresis8mV
SHDN
ThresholdSHDNlow0.70.3VSHDNHigh1.10.7
θJAThermalResistance220˚C/W
Note1:Absolutemaximumratingsarelimitsbeyondwhichdamagetothedevicemayoccur.OperatingRatingsareconditionsforwhichthedeviceisintendedtobefunctional,butdeviceparameterspecificationsmaynotbeguaranteed.Forguaranteedspecificationsandtestconditions,seetheElectricalCharacteristics.
Note2:Themaximumallowablepowerdissipationisafunctionofthemaximumjunctiontemperature,TJ(MAX),thejunction-to-ambientthermalresistance,θJA,andtheambienttemperature,TA.SeetheElectricalCharacteristicstableforthethermalresistance.Themaximumallowablepowerdissipationatanyambienttemperatureiscalculatedusing:PD(MAX)=(TJ(MAX)−TA)/θJA.Exceedingthemaximumallowablepowerdissipationwillcauseexcessivedietemperature.
Note3:Thehumanbodymodelisa100pFcapacitordischargedthrougha1.5kΩresistorintoeachpin.Themachinemodelisa200pFcapacitordischargeddirectlyintoeachpin.
Note4:ESDsusceptibilityusingthemachinemodelis150VforSWpin.
Note5:Alllimitsguaranteedatroomtemperature(standardtypeface)andattemperatureextremes(boldtypeface).Allroomtemperaturelimitsare100%productiontestedorguaranteedthroughstatisticalanalysis.AlllimitsattemperatureextremesareguaranteedviacorrelationusingstandardStatisticalQualityControl(SQC)methods.AlllimitsareusedtocalculateAverageOutgoingQualityLevel(AOQL).
Note6:Typicalnumbersareat25˚Candrepresentthemostlikelynorm.
