基于MAX17127設(shè)計(jì)的高效白光LED驅(qū)動(dòng)技術(shù)VIP

基于MAX17127設(shè)計(jì)的高效白光LED驅(qū)動(dòng)技術(shù)MAX17127是Maxim公司的高效白光LED(WLED)驅(qū)動(dòng)器,它的內(nèi)部開關(guān)電流模式升壓轉(zhuǎn)換器能驅(qū)動(dòng)LED陣列,多達(dá)并聯(lián)6串LED,每串13個(gè)LED.每串電流匹配達(dá)到±2%,輸入電壓5V-26V,可調(diào)電流從10mA到30mA.可調(diào)開關(guān)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(jì)算機(jī)顯示器.本文介紹了MAX17127主要特性,功能方框圖,以及典型應(yīng)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(yīng)用:

Automotive