Texas Instruments LM27952 Handleiding

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LM27952

V

IN

C

2

+

C

2

-

D1

3.3 µF

1 µF

V

OUT

3.3 µF

D4

PWM

C

1

+

C

1

-

1 µF

Capacitors: 1 µF - TDK C1608X7R1A105K

3.3 µF - TDK C2012X7R1A335K

or equivalent

V

IN

= 3.0V - 5.5V

I

DX

= 30 mA max

I

SET

GND

EN

D2

D3

R

SET

D

4

D

3

D

2

D

1

C

OUT

C

IN

C

1

C

2

LM27952

www.ti.com

SNVS364B–MAY2005–REVISEDMAY2013

LM27952WhiteLEDAdaptive1.5X/1XSwitchedCapacitorCurrentDriver

CheckforSamples:LM27952

1

FEATURES

APPLICATIONS

2

•Drivesupto4LEDswithupto30mAeach

•WhiteLEDDisplayBacklights

•Regulatedcurrentsourceswith0.2%(typ.)•WhiteLEDKeypadBacklights

matching

•GeneralPurposeLEDLighting

•3/2x,1xGaintransitionbasedonLEDV

F

DESCRIPTION

•PeakEfficiencyOver85%

TheLM27952isaswitchedcapacitorwhite-LED

•InputVoltageRange:3.0Vto5.5V

drivercapableofdrivingupto4LEDswith30mA

•PWMBrightnessControl

througheachLED.Its4tightlyregulatedcurrentsinks

•VerySmallSolutionSize-NOINDUCTOR

ensureexcellentLEDcurrentandbrightness

matching.LEDdrivecurrentisprogrammedbyan

•Fixed750kHzSwitchingFrequency

externalsenseresistor.TheLM27952operatesover

•<1µAShutdownCurrent

aninputvoltagerangefrom3.0Vto5.5Vandrequires

•14-pinWSONPackage:4.0mmX3.0mmX

onlyfourlow-costceramiccapacitors.

0.8mm

TheLM27952providesexcellentefficiencywithout

theuseofaninductorbyoperatingthechargepump

inagainof3/2,orinagainof1.Maximumefficiency

isachievedovertheinputvoltagerangebyactively

selectingthepropergainbasedontheLEDforward

voltagerequirements.

TypicalApplicationCircuit

1

Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsof

TexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.

2Alltrademarksarethepropertyoftheirrespectiveowners.

PRODUCTIONDATAinformationiscurrentasofpublicationdate.

Copyright©2005–2013,TexasInstrumentsIncorporated

ProductsconformtospecificationsperthetermsoftheTexas

Instrumentsstandardwarranty.Productionprocessingdoesnot

necessarilyincludetestingofallparameters.

Product specificaties