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MCU

LP8550

SW

FB

V

LDO

GNDs

EN

ISET

V

DDIO

PWM

SCLK

SDA

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

L1D1

10V ± 40V

5.5V ± 22V

FILTER

5V

FSET

15 éH

VSYNC

210 mA ± 400 mA

C

OUT

C

IN

10 éF

4.7 éF

C

VLDO

1 éF

V

DDIO

reference voltage

VSYNC signal

120 k5

100 nF

1 éF

FAULT

Can be left floating

if not used

39 pF

VIN

R

ISET

R

FSET

V

BATT

0102030405060708090100

60

65

70

75

80

85

90

95

100

EFFICIENCY (%)

DUTY CYCLE (%)

VIN = 9V

VIN = 12V

Product

Folder

Sample &

Buy

Technical

Documents

Tools &

Software

Support &

Community

LP8550

SNVS657E–SEPTEMBER2010–REVISEDSEPTEMBER2014

LP8550High-EfficiencyLEDBacklightDriverforNotebooks

1Features3Description

TheLP8550isawhite-LEDdriverwithintegrated

1

•High-VoltageDC/DCBoostConverterwith

boostconverter.Ithassixadjustablecurrentsinks

IntegratedFETwithFourSwitchingFrequency

whichcanbecontrolledbyPWMinputorwithI

2

C-

Options:156/312/625/1250kHz

compatibleserialinterface.Theboostconverterhas

•2.7-Vto22-VInputVoltageRangetoSupport1x

adaptiveoutputvoltagecontrolbasedontheLED

to5xCellLi-IonBatteries

drivervoltages.Thisfeatureminimizesthepower

consumptionbyadjustingthevoltagetolowest

•ProgrammablePWMResolution

sufficientlevelinallconditions.

–8to13TrueBits(SteadyState)

LEDoutputshave8-bitcurrentresolutionandupto

–Additional1to3BitsUsingDitheringDuring

13-bitPWMresolutionwithadditional1-to3-bit

BrightnessChanges

ditheringtoachievesmoothandprecisebrightness

•I

2

CandPWMBrightnessControl

control.ProprietaryPhaseShiftPWMcontrolisused

•AutomaticPWM&CurrentDimmingforImproved

forLEDoutputstoreducepeakcurrentfromthe

Efficiency

boostconverter,thusmakingtheboostcapacitors

smaller.ThePhaseShiftingschemealsoeliminates

•PWMoutputfrequencyandLEDCurrentset

audiblenoise.

throughResistors

AutomaticPWMdimmingatlowerbrightnessvalues

•OptionalSynchronizationtoDisplayVSYNC

andcurrentdimmingathigherbrightnessvaluescan

Signal

beusedtoimprovetheopticalefficiency.Internal

•SixLEDOutputswithLEDFault(Short/Open)

EEPROMisusedforstoringtheconfigurationdata.

Detection

Thismakesitpossibletohaveminimumexternal

•LowInputVoltage,Overtemperature,Overcurrent

componentcountandmakethesolutionverysmall.

Detection,andShutdown

TheLP8550hassafetyfeatureswhichmakeit

•MinimumNumberofExternalComponents

possibletodetectLEDoutputswithopenorshort

fault—lowinputvoltageandboostovercurrent

2Applications

conditionsaremonitored,andchipisturnedoffin

caseoftheseevents.Thermalde-ratingfunction

•NotebookandNetbookLCDDisplayLED

preventsoverheatingofthedevicebyreducing

Backlight

backlightbrightnesswhensettemperaturehasbeen

•LEDLighting

reached.

DeviceInformation

(1)

PARTNUMBERPACKAGEBODYSIZE(MAX)

LP8550DSBGA(25)2.49x2.49mm

(1)Forallavailablepackages,seetheorderableaddendumat

theendofthedatasheet.

SimplifiedSchematicLEDEfficiency

1

AnIMPORTANTNOTICEattheendofthisdatasheetaddressesavailability,warranty,changes,useinsafety-criticalapplications,

intellectualpropertymattersandotherimportantdisclaimers.PRODUCTIONDATA.

Produktspecifikationer