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confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 1 orderinginformation typicalapplication partnumber top marking ambient temperaturerange package rohsstatus MAP3249sirh MAP3249 40 to+85 16leadssoic halogenfree MAP3249terh MAP3249 40 to+85 16leadsetssop halogenfree applications highbrightnesswhiteledbacklightingforlcd tvsandmonitors generalledlightingapplications datasheet MAP3249 4 channelleddriverforh i ghbrightnessleds generaldescription MAP3249 is a 4channel led driver optimized for ledbacklightapplicationtargetingmidandlarges ize lcd module. MAP3249 uses the boost mosfet externallyand4channelcurrentsourcesinternally for drivinghighbrightnesswhiteleds. MAP3249has55vabsolutemax.ratingfbpinsand inputvoltageisrangedfrom8.5v~28vandmaxled currentis200maperchannel. MAP3249 features internal softstart and 2.5% led current accuracy including matching between channels. MAP3249 has various protections like output over voltage, led short/open, open schottky diode, uvlo andthermalshutdown. MAP3249hasanunusedchanneldetectionfunction tonotboosttheoutputvoltagetoovpatstartup. MAP3249 isavailable16 leads soicand etssop withhalogenfree(fullyrohscompliant). features 8.5vto28vinputvoltagerange driveupto4channels 55vfbpinvoltage 0.4vheadroomvoltage 200maoutputcurrentperchannel 2.5%currentaccuracy programmableboostswitchingfrequency (100khz~500khz) ledcurrentsetbyboth pwmandexternaldcvoltage unusedchanneldetection boostovercurrentprotection outputovervoltageprotection ledshort/openprotection schottkydiodeopenprotection uvlo
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 2 pinconfiguration soic/etssop16l functionalblockdiagram
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 3 pindescription 16leads etssop 16leads soic name description 1 1 vldo internal5.2vregulatoroutput.needexternal capacitortostabilize. 2 2 comp internalerroramplifiercompensation(note1) 3 3 adim settingforledcurrentthruexternaldcvolta ge 4 4 iset settingforledcurrentreferenceresistor(no te2) 5 5 en enable.activehigh. 6 6 fsw settingforboosterswitchingfrequency(note3 ) 7 7 fb4 ledcurrentsinkforch4(note4) 8 8 fb3 ledcurrentsinkforch3(note4) 9 9 fb2 ledcurrentsinkforch2(note4) 10 10 fb1 ledcurrentsinkforch1(note4) 11 11 ovp outputovervoltagesense(note5) 12 12 cs externalboostcurrentsense(note6) 13 13 gate gatedriveroutputforexternalboostmosfet 14 14 pwm pwmsignalinputfordimming(note7) 15 15 gnd ground 16 16 vin powersupplyinput.needexternalbypasscapaci tor. exposed pad connecttogndbymultipleviasforheatsinking purpose(note8) note1 :connectexternalcapacitorandresistortocompp in.refertotypicalapplicationdiagram note2 :theresistorvalueonisetpincontrolsthefull scalelevelofsinkcurrentonfbpins.donotlea vethispinopen. note3 :connectexternalresistortosettheoscillatorf requencyfrom100khzto500khz note4 :ifnotused,connecttognd. note5 :.connectcenternodeofresistivevoltagedivider fromoutputtoground.refertoatypicalapplicati ondiagram note6 :connectexternalresistortogndtosensetheext ernalpowermosfetdraincurrent note7 :thisexternalpwmsignalisusedforbrightnessc ontrol note8 :notconnectedinternally.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 4 absolutemaximumratings (note1) symbol parameter min max unit v vin supplyvoltage 0.3 30 v v en ,v cs ,v vldo ,v pwm ,v comp ,v ovp , v gate , v iset, v fsw, v adim en,cs,vldo,pwm,comp,ovp,gate,iset,fsw,adim pins 0.3 6 v v fb1~4 fb1~fb4pins 0.3 55 v i fb1~4 fb1~fb4pins 200 ma t pad solderinglead/padtemperature10sec 300 c t j junctiontemperature 40 +150 c t s storagetemperature 65 +150 c esd hbmonallpins(note2) 2000 +2000 v mmonallpins(note3) 200 +200 note 1 : stresses beyond the above listed maximum ratings may damage the device permanently. operating above the recommended conditions for extended time may stress the device and affect device reliability. also the device may not operate normally above the recommendedoperatingconditions.thesearestress ratingsonly. note2 :esdtestedperjesd22a114. note3 :esdtestedperjesd22a115. recommendedoperatingconditions (note1) parameter min max unit v vin supplyinputvoltage 8.5 28 v i fb1~4 ledcurrentsinkpin 90 200 ma v fb1~4 ledcurrentsinkpin 55 v t a ambienttemperature(note2) 40 +85 c note1 :normaloperationofthedeviceisnotguaranteed ifoperatingthedeviceoveroutsiderangeofrecom mendedconditions. note2 :theambienttemperaturemayhavetobederatedif usedinhighpowerdissipationandpoorthermalre sistanceconditions. packagethermalresistance (note1) parameter ja jc unit MAP3249sirh 16leadssoic 80 49 /w MAP3249terh 16leadsetssop 60 19 /w note1 :multilayerpcbbasedonjedecstandard(jesd517 )
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 5 electricalcharacteristics unlessnoted,v vin =12v,c vin =1.0 f,andtypicalvaluesaretestedatt a =25 c. parameter testcondition min typ max unit generalinputoutput v vin inputvoltagerange 8.5 28 v i q quiescentcurrent drivingfbsatmin.settingwith noload 4 10 ma i sd groundpincurrentin shutdown v vin =12v,v en =0v noloadcurrentonfb 40 a v en logicinputlevelon enpin v en_l :logiclow 0.8 v v en_h :logichigh 2.2 r en pulldownresistoronenpin 250 500 k v uvlo undervoltagelockout thresholdvoltageonvinpin stopthreshold 6.5 7.0 v startthreshold 7.5 8.2 oscillator f sw internaloscillator frequency r fsw =250k 180 200 220 khz r fsw =100k 425 500 575 d max max.dutycycle 85 90 % reference v vldo ldovoltage v vin 8.5v,0mai ldo 10ma 4.95 5.2 5.45 v protection t sd thermalshutdown temperature shutdowntemperature 150 c hysteresis, t sd 25 v ovp overvoltagethreshold onovppin risingovervoltagelimitonovppin 2.35 2.5 2.65 v hysteresis, v ovp 0.1 v led_short ledshortprotection thresholdonfbpins fb1~fb4 8.5 v t scp ledshortprotectiontime f sw =500khz(note1,2) 8.192 ms v cs boostovercurrentprotection thresholdoncspin 0.57 0.6 0.63 v v open ledopenprotection thresholdonfbpins i led =90ma 0.09 v i led =200ma 0.2 v sbdopen sbdopenprotection thresholdonovppin 0.1 v ledcurrentsinkregulator v fb1~4 min.fb1~fb4voltage 0.4 v i fb currentaccuracy i led =120ma 2.5 +2.5 % i fb_max currentsinkmax.current v adim =2.0v 200 ma i fb_leakage currentsinkleakagecurrent v pwm =0v,vfb=30v 5 ua v adim adiminputvoltagerange 0.9 2.0 v pwminterface f pwm pwmdimmingfrequency 0.1 2.0 khz v pwm logicinputlevelon pwmpin v pwm_l :logiclow 0.8 v v pwm_h :logichigh 2.2 t on_min min.ontime(note1) f sw =200khz 7 us r pwm pulldownresistoronpwmpin 250 500 k boostmosfetgatedriver v gate gatedrivevoltage v vin 8.5v 4.95 5.2 5.45 v i source gatesourcecurrent v vin 8.5,v gate =0.9*v vldo 35 ma i sink gatesinkcurrent v vin 8.5v,v gate =0.1*v vldo 30 ma t rise gateoutputrisingtime gateload:10 /1nf 0.1 0.5 us t fall gateoutputfallingtime gateload:10 /1nf 0.1 0.5 us softstart t ss softstarttime f sw =200khz(note1) 8.5 13.0 ms note1 :theseparameters,althoughguaranteedbydesign, arenottestedinmassproduction. note2 : 4096 1 = fsw tscp
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 6 typicaloperatingcharacteristics unlessotherwisenoted,v in =12v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 90 100 110 120 130 140 150 160 170 180 190 200 v adim .vs.i led vadim[v] iled[ma] 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 v adim .vs.v fb (headroom) vadim[v] vhr[v] 50 30 10 10 30 50 70 90 110 130 0 2 4 6 8 10 temp.vsiq i q ,quiescentcurrent(ma) temperature( o c) 50 30 10 10 30 50 70 90 110 130 25 35 45 55 65 temp.vsisd i sd ,shutdowncurrent[a] temperature[ o c] 50 30 10 10 30 50 70 90 110 130 5.8 6.2 6.6 7.0 7.4 7.8 8.2 temp.vsuvlo v uvlo_l v uvlo ,undervoltagelockout[v] temperature[ o c] v uvlo_h 50 30 10 10 30 50 70 90 110 130 180 190 200 210 220 temp.vsfsw f osc_200khz ,frequency(200khz)[khz] temperature[ o c]
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 7 typicaloperatingcharacteristics unlessotherwisenoted,v in =12v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c. 50 30 10 10 30 50 70 90 110 130 5.0 5.0 5.1 5.2 5.3 5.4 temp.vsvldo v ldo ,lowdropoutvoltage[v] temperature[ o c] 50 30 10 10 30 50 70 90 110 130 117 118 119 120 121 122 123 temp.vsiled i fb1 i fb2 i fb3 i fb4 i fbx ,fbcurrent[ma] temperature[ o c] 50 30 10 10 30 50 70 90 110 130 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 temp.vsven v en_l v en ,enablethresholdvoltage[v] temperature[ o c] v en_h 50 30 10 10 30 50 70 90 110 130 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 temp.vsvpwm v pwm_l v pwm ,pwmthresholdvoltage[v] temperature[ o c] v pwm_h 50 30 10 10 30 50 70 90 110 130 2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60 2.65 temp.vsovp v ovp_l v ovp ,overvoltageproction thresholdvoltage[v] temperature[ o c] v ovp_h 60 40 20 0 20 40 60 80 100 120 140 0.57 0.58 0.59 0.60 0.61 0.62 0.63 temp.vsvcs v cs ,boostovercurrentprotection thresholdvoltage[v] temperature[ o c]
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 8 typicaloperatingcharacteristics unlessotherwisenoted,v in =12v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 9 typicaloperatingcharacteristics unlessotherwisenoted,v in =12v,cin=220uf,cout=100uf,riset=10k , rfsw=250k andt a =25 c.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 10 applicationinformation currentmodeboostswitching controlleroperation the MAP3249 employs current mode control boost architecture that has a fast current sense loop and a slowvoltagefeedbackloop.sucharchitectureachie ves a fast transient response that is essential for the led backlightapplication. dynamicheadroomcontrol the MAP3249 features a proprietary dynamic headroom control circuit that detects the lowest voltage from any of the fb1fb4 pins. this lowest channelvoltageisusedasthefeedbacksignalfor the boostcontroller.sinceallledstacksareconnecte din parallel to the same output voltage, the other fb p ins will have a higher voltage, but the regulated curre nt source circuit on each channel will ensure that eac h channelhasthesamecurrent. internal5.2vregulator theMAP3249hasbuiltin5.2vldoregulatortosupp ly internalanalogandlogicblocks.theldoispowere dup whentheenpinislogichigh.a2.2ufbypasscapac itoris requiredonthevldopinforstableoperationofth eldo. dimmingscheme thebrightnesscontroloftheledsisperformedby a pulsewidthmodulationofthechannelcurrent.when a pwm signal is applied to the pwm pin, the current generatorsareturnedonandoffmirroringthepwm pin behavior. when pwm signal stays at low level (<0.8v), the MAP3249 turns off the boost circuitry, but internal circuitisenabledsotheMAP3249increasestheout put voltagepromptly. min.pwmdimmingontimeofMAP3249ismax.10usat 200khz boost switching frequency. thus, following t able shows min. pwm dimming dutycycle at various pwm inputfrequencyat200khzboostswitchingfrequency . fpwm[hz] min.dutycycle 100 0.30% 200 0.40% 300 0.43% 400 0.48% 500 0.50% 1000 0.70% 1500 1.20% 2000 1.70% paralleloperation even the MAP3249 has 4 channels and 200ma led current capability per channel, 2 channels and 400m a applicationcanbesupportedbytying2fbsinto1ch ,so theledcurrentcapabilitycanbeincreasedto400m a. ledcurrentadjustment the MAP3249 sets the led current through the voltage level on the adim pin. adim pin voltage vs. ledcurrentisasfollowingtable. the riset /1% resistor must be connected between theisetpinandground. riset10 k ? adimvoltage[v] ledcurrent[ma] 0.9 90 1.0 100 1.2 120 1.4 140 1.6 160 1.8 180 2.0 200 the relationship between adim pin voltage, riset valueandledcurrentisdefinedbyfollowingequat ion. 1000 ] [ ] [ ] [ = k iset adim led r v v ma i the MAP3249 offers protection functions to limit ex cess led current increase at abnormal iset and adim pin voltage. if the adim or iset pin voltage is at foll owing conditions abnormally, the MAP3249 turns off the ga te outputandinternalledcurrentsinkmosfets. v_iset 0.3v v_adim 2.6v boostswitchingfrequency the switching frequency of the MAP3249 should be programmed between 100khz and 500khz by an external resistor connected between the fsw pin and ground. do not leave this pin open. the approximate operatingboostswitchingfrequencycanbecalculat ed byfollowingequation. ] [ 50 ] [ = k r mhz f fsw sw ifthefswpinvoltageisdecreasedtobeloworequ al to 0.6v abnormally the MAP3249 turns off the gate outputtoprotectexcessswitchingfrequencyincrea se.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 11 startup (1) the MAP3249 has softstart circuitry internally andthesoftstarttime(tss)istypical8.5ms. (2) unused channel detection function therecanbeexistapplicationswhichdonotuse all the fb pins(4 channel). conventional multi channel led drivers boost the output voltage to ovpleveltocheckopenfb(s). the MAP3249 detects unused fb(s) and excludes corresponding fb(s) automatically from headroom control before startup. the unused fb(s) must be connected to gnd. this ensures the output voltage is not boosted to ovp level at startup. if the unused fb(s) are not connected to gnd,theoutputvoltageisboosteduptoovplevel likeconventionalboostleddriver. these features significantly reduce the startup currentandpreventabnormaloperationatstartup. outputovervoltageprotection toprotecttheboostconverterwhentheloadisope n or the output voltage becomes excessive for any reason,theMAP3249featuresadedicatedovervoltag e feedbackinput.theovppinisconnectedtothecen ter tap of a resistive voltagedivider from the high vo ltage output. whentheovppinvoltageexceedstypical2.5v,a comparator turns off the external power mosfet. thi s switchisreenabledaftertheovppinvoltagedrop stypical 100mvhysteresisbelowtheprotectionthreshold.th isover voltageprotectionfeatureensurestheboostconver terfail safe operation when the led channels are disconnect ed fromtheoutput. a 5v zener diode is recommendable to avoid pin damagewhenthervoplresistorisopenabnormally. theovpvoltageofoutputvoltagecanbecalculated by followingequation. ) 1( 5.2 ] [ _ ovpl ovph ovp out r r v v + = undervoltagelockout if the input voltage falls below the uvlo level of typical 6.5v on the vin pin, the device will stop switchingandbereset.operationwillrestartwhen the vin pin voltage rises to 7.5v. this ensures failsa fe operation when the input voltage falls below min. v in voltageofic. sbdopenprotection when ovp pin voltage is less than 0.1v, the MAP3249turnsoffthegateoutput. this protects the driver from damage if the output schottkydiodeisopen(defectiveorpoorsoldercon tact).
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 12 boostovercurrentprotection the MAP3249 features overcurrent protection (ocp)bysensingcspinvoltage.thiscspinisuse d forinductorcurrentsensingforcurrentmodecontr olas well. if the cs pin voltage exceeds typical 0.6v, the MAP3249turnsoffthegateoutput. the internal ocp sensing voltage decreases with increase of gate dutycycle due to internal slope compensationwhichensuresstableccmoperation. followinggraphshowstherelationshipbetweengate dutycycleandinternalocpsensingtypicalvoltage . 56125 .0 21255 .0 ] .[ _ _ + ? = d v typ ocp vcs rcs setting procedure (1) chooseboostinductorvalue once the led current, the input and output voltage and the switching frequency are fixed, the inductan ce value defining the boundary between dcm and ccm operationcanbecalculatedas; sw o b f d d r h l ? = 2 ) 1( ] [ 2 where,ro=vout/iout (2) find peak inductor current at selected boost inductance l f d v i sw ovp in dcm peak l = ) ( _ _ l f d v i i sw ovp in ovp in ccm peak l + = 2 ) ( ) ( _ _ the rcs value should be chosen that the output voltage can be boosted up to ovp level. and the iou t value should be considered with max. 3 channel because the ovp is occurred led open event only. thus, in fb ch led ovp out ovp in v n i v a i ? = )1 ( ] [ / _ ) ( :efficiency n fb :thenumberofusingchannel (3) findtypicalvcs_ocpvalueatgivend(ovp) 56125 .0 21255 .0 ] .[ _ _ ) ( + ? = ovp d v typ ocp vcs (4) findrcsvalue in order to avoid touching the current limit during normal operation, the voltage across the current sensing resistor rcs should be less than 80% of the worstcasecurrentlimitvoltage. peak l typ ocp cs cs i v r _ _ _ 8.0 ] [ = example vin=24v,vout_ovp=55v,=90%, iled/ch=100ma, ledstring=4x16,fsw=200khz (1) chooseboostinductorvalue ] [5. 37 2 ) 1( 2 h f d d r l sw o b = ? = in this case, chosen inductance value is 47uh for ccmoperation. (2) findpeakinductorcurrent ] [ 76 .0 )1 4( / _ ) ( a v i v i in ch led ovp out ovp in = ? = ] [ 48 .1 2 ) ( ) ( _ _ a l f d v i i sw ovp in ovp in ccm peak l = + = (3) findtypicalvcs_ocpvalueatgivend(ovp) ] [ 441 .0 56125 .0 21255 .0 _ _ ) ( v d typ ocp vcs ovp = + ? = (4) findrcsvalue ] [ 24 .0 8.0 _ _ _ = = peak l typ ocp cs cs i v r mx provides design spreadsheet for MAP3249 ver0.0 foreaseexternalcomponentscalculation.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 13 ledopenprotection open threshold ovp led open protection incasethevoltageonanyofledcurrentsinkpins (fb1~4)isbelowledopenprotectionthresholddue toledopen duringnormaloperation,theoutputvoltageisboos tedupto100%ofovplevelandtheMAP3249automat icallyexcludes thecorrespondingchannelandremainingstring(s)w illcontinueoperation. ledshortprotection if the voltage at any of the fb14 pins exceeds led short detection voltage(typ. 8.5v) due to led shor t during normaloperationandpersistsfortscp,theMAP3249 automaticallyturnsoffthecorrespondingchannel andremaining channel(s)willcontinueoperation. theprotectionstatusislatchedinternallyandcan beclearedbyrecyclingtheenpinorapplyingac ompletepower onreset(por). when led(s) is(are) open on any channel, the output voltage is boosted up to ovp level and this can ca use abnormalledshortprotectionduetohighfbvoltag e.toavoidthisabnormaloperation,theMAP3249di sablesthe ledshortprotectionfunctionwithrelatedtomin. fbvoltageconditions. min.vfb 2.60v=>ledshortprotectiondisable min.vfb 2.15v=>ledshortprotectionenable
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 14 operationtimingchart acapacitoronthevldopinbeginscharingafteren isturnedon.oncethevinvoltagereachesabout7 .5v(see uvlo specification), the internal uvlo is released. the MAP3249 checks the initial open fb(s) and excl udes corresponding fb(s) from headroom control before in ternal pg signal is set up. the unused fb(s) must be connected to gnd. internalcontrollerstartsboostingwithfirstpwm inputandperformssoftstart.aftersoftstartis endorduringsoftstartperiod,theoutputvoltage isboosteduptoregulationvoltage(totalforward voltageofled bar+fbvoltage)withouttouchingovplevelandth econtrollerperformsheadroomcontrol. theMAP3249booststheoutputvoltageonlyincondi tionthatvinisappliedanden,pwmandadimistu rnedon.and thereisnolimitationwithregardtoturnonseque nce.butincasethatvin(inputvoltageofbooster) isappliedlastlyafter en,pwmandadimisturnedon,thestartupcurrent isincreasedbecausetheoutputvoltageisboosted from0v. ifthepwmsignalremainslogiclowforoverthan1 6.4ms(1/fsw*8192)at500khzboostswitchingfrequ encyduring normaloperation,thecontrollerregardsitasdim zerocondition.becauseofdischargeofoutputcapa citorthroughthe ovpsensingresistorsduringthedimzerotime,the outputvoltagegettingdeclined.theMAP3249perfo rmssoftstartas soonaspwmsignalrisestoboosttheoutputvoltag erapidly. thecontrollerstopsswitchingrightafterenistu rnedoff.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 15 externalcomponentsselection inductor the inductor value should be decided before system design. because the selection of the inductor affec ts the operating mode of ccm(continuous conduction mode)ordcm(discontinuousconductionmode). the inductance value defining the boundary between dcmandccmoperationcanbecalculatedas; sw o b f d d r h l ? = 2 ) 1( ] [ 2 where,ro=vout/iout in ccm operation, inductor size should be bigger, even though the ripple current and peak current of inductor can be small. in dcm operation, even rippl e current and peak current of inductor should be larg e whiletheinductorsizecanbesmaller. the inductor dc current or input current can be calculatedasfollowingequations. in out out in v i v a i = ] [ ?Cefficiencyoftheboostconverter thenthedutyratiois, d out d in out v v v v v d + + ? = v d C forward voltage drop of the output rectifying diode when the boost converter runs in dcm ( l < l b ), it takes the advantages of small inductance and quick transientresponse.theinductorpeakcurrentis, l f d v i sw in dcm peak l = _ _ theconverterwillworkinccmifl>l b ,generallythe converter has higher efficiency under ccm and the inductorpeakcurrentis, l f d v i i sw in in ccm peak l + = 2 _ _ boost mosfet thecriticalparametersforselectionofamosfet are: 1.maximumdraincurrentrating,i d(max) 2.maximumdraintosourcevoltage,v ds(max) 3.onresistance,r ds(on) 4.gatesourcechargeq gs andgatedrainchargeq gd 5.totalgatecharge,q g the maximum current through the power mosfet happens when the input voltage is minimum and the outputpowerismaximum.themaximumrmscurrent throughthemosfetisgivenby; max max in max rms d i i = ) ( ) ( theoffstatevoltageofthemosfetisapproximatel y equaltotheoutputvoltageplusthediodev f .therefore, v ds(max) ofthemosfetmustberatedhigherthanthe maximumoutputvoltage(ovpvoltage). the power losses in the mosfet can be separated into conduction losses and switching losses. the conduction loss, pcond, is the i2r loss across the mosfet.theconductionlossisgivenby; k i r p rms on ds cond = 2 ) ( wherekisthetemperaturecoefficientofthemosfe t. the switching loss is related to q gd and q gs1 which determine the commutation time. q gs1 is the charge betweenthethresholdvoltageandtheplateauvolta ge when a driver charges the gate, which can be read i n thechartofv gs vs.q g ofthemosfetdatasheet.q gd is the charge during the plateau voltage. these two parametersareneededtoestimatetheturnonandt urn offloss. sw in ds plt dr g gd sw in ds th dr g gs sw f i v v v r q f i v v v r q p ? + ? = 1 wherev th isthethresholdvoltage,v plt istheplateau voltage, r g is the gate resistance, v ds is the drain sourcevoltage,v dr isthedrivevoltage the total gate charge, q g , is used to calculate the gatedriveloss.theexpressionis sw dr g dr f v q p = fast switching mosfets can cause noise spikes whichmayaffectperformance.toreducethesespike s adriveresistorcanbeplacedbetweengatepinand themosfetgate.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 16 output rectifying diode schottky diodes are the ideal choice for MAP3249 due to their low forward voltage drop and fast switching speed. make sure that the diode has a voltage rating greater that the possible maximum outputvoltage.thediodeconductscurrentonlywhe n thepowerswitchisturnedoff. input capacitor in boost converter, input current flows continuousl y into the inductor; ac ripple component is only proportional to the rate of the inductor charging, thus, smallervalueinputcapacitorsmaybeused.ensure the voltage rating of the input capacitor is suitable t o handlethefullsupplyrange. a capacitor with low esr should be chosen to minimizeheatingeffectsandimprovesystemefficie ncy. output capacitor the output capacitor acts to smooth the output voltage and supplies load current directly during t he conduction phase of the power switch. output ripple voltage consists of the discharge of the output capacitor during the fet ton period and the voltage dropduetoloadcurrentflowingthroughtheesrof the output capacitor. the ripple voltage is shown in followingequation. esr i f c d i v out sw out out out + = assume a ceramic capacitor is used. the minimum capacitanceneededforagivenripplecanbeestima ted byfollowingequation. out sw out out out in out v f v i v v c ? = ) ( loop compensation theMAP3249controlsincurrentmode.currentmode easily achieves compensation by consisting simple single pole from double pole that lc filer makes at voltage mode. in general, crossover frequency is selected from 1/3 ~ 1/6 range of the switching frequency.iffcislarge,thereispossibilityof oscillation tooccur,althoughtimeresponsegetsbetter. ontheotherhand,iffcissmall,timeresponsewi llbe bad, while it has improved stability, which may cau se overshootorundershootinabnormalcondition. layout consideration agatedrivesignaloutputfromgatepinbecomes noisesource,whichmaycausemalfunctionoficdue to crosstalkifplacedbythesideofananalogline. itis recommendedtoavoidplacingtheoutputlineespeci ally bythesideofcs,adim,iset,fsw,ovp,comppins asfaraspossible. (1) soic (2) etssop exposedpadshoudbetiedtogndwith multiplevias
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 17 thermal consideration forcontinuousoperation,donotexceedabsolute maximumjunctiontemperature.themaximumpower dissipationdependsonthethermalresistanceofth eic package,pcblayout,rateofsurroundingairflow,a nd differencebetweenjunctionandambienttemperature . themaximumpowerdissipationcanbecalculatedby thefollowingformula: ja a max j max t t pd ? = ) ( ) ( wheret j(max) isthemaximumjunctiontemperature,t a istheambienttemperature,and ja isthejunctionto ambientthermalresistance. themaximumpowerdissipationdependsonthe operatingambienttemperatureforfixedt j(max) and thermalresistance, ja .fortheMAP3249packages, thederatingcurveinfollowinggraphallowsthe designertoseetheeffectofrisingambienttemper ature onthemaximumpowerdissipation. foratypicalapplication,theoperationpoweroft heic canbecalculatedroughlyby; pd = ( v in ? i in ) + ( v fb1 ? i fb1 +???+ v fb4 ? i fb4 ) ? d pwm wherev in representstheinputvoltageatthevinpinof theicandi in representsthecurrentflowintothevin pinoftheic.d pwm isdutycycleofpwminputsignal.
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 18 physicaldimensions 16leadsetssop symbol dimension(mm) min nom max a 1.20 a1 0.00 0.15 a2 0.80 1.05 b 0.19 0.30 c 0.09 0.20 d 4.90 5.10 d1 2.20 ` e 6.40bsc e1 4.30 4.50 e2 2.20 e 0.65bsc l 0.45 0.75 l1 1.00ref l2 0.25ref 1 0 8
confidential datasheetversion1.2 oct8 th 2014 MAP3249C4channelleddriverforhighbrightness leds 19 magnachipsemiconductorltd. doesntnotrecommendtheuseofitsproductsinh ostileenvironments,including,withoutlimitation, aircraft,nuclearpowergeneration,medicalapplian ces,anddevicesorsystemsinwhichmalfunctionof anyproductcanreasonably beexpectedtoresultinapersonalinjury.seller scustomersusingorsellingsellersproductsfor useinsuchapplicationsdosoat theirownriskandagreetofullydefendandindemn ifyseller. magnachip reserves the right to change the specifications an dcircuitry without notice at any time. magnachip does not consider responsibilityforuseofanycircuitryotherthan circuitryentirelyincludedina magnachip product. isaregisteredtrademarkofmagnachipsemiconducto rltd. magnachipsemiconductorltd. 891,daechidong,kangnamgu,seo ul,135738korea tel:82269033451/fax:82269033668~9 www.magnachip.com 16 leads soic

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Price & Availability of MAP3249

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