基于MAX17127設計的高效白光LED驅動技術

基于MAX17127設計的高效白光LED驅動技術MAX17127是Maxim公司的高效白光LED(WLED)驅動器,它的內部開關電流模式升壓轉換器能驅動LED陣列,多達并聯(lián)6串LED,每串13個LED.每串電流匹配達到±2%,輸入電壓5V-26V,可調電流從10mA到30mA.可調開關頻率從250kHz到1MHz.主要用在汽車電子系統(tǒng),手持終端以及筆桿子電腦和便攜式計算機顯示器.本文介紹了MAX17127主要特性,功能方框圖,以及典型應用電路.

TheMAX17127isahigh-efficiencydriverforwhitelight-emittingdiodes(LEDs).Itisdesignedforlargeliquid-crystaldisplays(LCDs)thatemployanarrayofLEDsasthelightsource.Aninternalswitchcurrent-modestep-upconverterdrivestheLEDarray,whichcanbeconfiguredforuptosixstringsinparalleland13LEDsperstring.Eachstringisterminatedwithballastthatachieves±2%current-regulationaccuracy,ensuringevenLEDbrightness.TheMAX17127hasawideinput-voltagerangefrom5Vto26V,andprovidesanadjustable10mAto30mAfull-scaleLEDcurrent.

TheMAX17127canimplementbrightnesscontrolthroughthePWMsignalinput,andLEDcurrentisdirectlycontrolledbytheexternaldimmingsignal’sfrequencyanddutycycle.

TheMAX17127hasmultiplefeaturestoprotectthecontrollerfromfaultconditions.Onceanopen/shortstringisdetected,thefaultstringisdisabledwhileotherstringscanstilloperatenormally.Thecontrollerfeaturescycle-by-cyclecurrentlimittoprovideconstantoperationandsoft-startcapability.IftheMAX17127isincurrent-limitcondition,thestep-upconverterislatchedoffafteraninternaltimerexpires.Athermal-shutdowncircuitprovidesanotherlevelofprotection.Whenthermalshutdownhappens,theMAX17127islatchedoff.

TheMAX17127’sstep-upcontrollerfeaturesaninternal0.12Ω(typ),48V(max)powerMOSFETwithlocalcurrent-senseamplifierforaccuratecycle-by-cyclecurrentlimit.ThisarchitecturegreatlysimplifiestheexternalcircuitryandsavesPCBspace.Low-feedbackvoltageateachLEDstringhelpsreducepowerlossandimproveefficiency.TheMAX17127featuresresistor-adjustableswitchingfrequencyfrom250kHzto1MHz,whichenablesawidevarietyofapplicationsthatcantradeoffcomponentsizeforoperatingfrequency.

TheMAX17127isavailableinathermallyenhanced,lead-free,20-pin,4mmx4mmthinQFNpackage.

MAX17127主要特性:

5Vto26VInputSupplyVoltage

UptoSixParallelStringsMultipleSeries-ConnectedLEDs

250kHzto1MHzAdjustableSwitchingFrequency

0.12ΩInternalHVPowerMOSFET(48Vmax)

LowStringFeedbackVoltage:480mVat20mALEDCurrent

Full-ScaleLEDCurrentAdjustablefrom10mAto30mA

±2%Current-RegulationAccuracyBetweenStrings

400nsMinimumStringOn-Time

100Hzto25kHzPWMInputRange

OpenandShortLEDProtection

OutputOvervoltageProtection

ThermalShutdown

Small20-Pin,4mmx4mmThinQFNPackage

MAX17127應用:

Automotive