1、LED Lighting Driver IC IntroductionRobin LiaoJanuary 2011http:/ Lighting Driver IC OverviewAC input to constant current LED driver - IsolatedAC input to constant current LED driver - Non-isolated DC to CC SolutionApplicationsSelection Guide 3LED Lighting Driver IC Overview4LED Lighting Driver IC Ove

2、rviewLED LightingAC/CCDC/CCIsolatedNon-isolatedWith ETWithout ETE26/E27/E17, T5/T8 Par30/Par38, Street lightGU10, E26/E27/E17 T5/T8, Par30/Par38MR16, AR111Street light, car light, desk light, freeze light, projector Emergency light 5AC input to constant current LED driver - Isolated6AC Input Solutio

3、n - Isolated Application E27, GU10 . Bulb, Par 30, Par 38 T5, T8 . Light bar, Freeze light Street light, Desk light Richtek advantage High-precision constant current control to limit current accuracy in +/-5% range on mass production. Small package and high integrated solution with less external com

4、ponents to fit into a small bulb or light bar Very low quiescent current Dimming on secondary side to provide better accuracy7Secondary side CC/CV controllerAC to CC Isolated secondary side CC/CV controller & dimmingRT8456RT8454RT8457Single channel CC/CV controllerSingle channel CC/CV controller

5、 with dimmingMulti-channel CC/CV controller with dimmingl Easily work with any kind of primary side topology.l Provide high precision LED current.lLED current accuracy does not vary with the accuracy of transformer.lOVP support8RT8456 Secondary-side constant Current ControllerSecondary side LED curr

6、ent regulationSupport LED voltage up to 45VHigh accuracy LED current threshold control over wide input voltage and temperature range0.6mA operation currentProgrammable LED current through 60mV sense resisterProgrammable OVPEasily connected to different kinds of primary side solutionsTSOT 23-69RT8457

7、: Dimmable secondary side constant current controllerLED voltage up to 45VSupport Triac dimming, PWM dimming, analog dimmingHigh accuracy LED current threshold control over wide input voltage and temperature range Programmable LED current through 60mV sense resisterProgrammable OVPEasily connected t

8、o different kinds of primary side solutionsSOP-8Dimming Input10RT8454 AC-CC 6-Ch Current RegulatorsVcc up to 50VProgrammable channel current3% current sense amplifier input offsetEasy dimmingProgrammable soft start and OVPAutomatic detecting unconnected AND/OR broken channel to avoid output over vol

9、tageVcc under voltage lockout and Thermal shutdownOne LDO controller embedded11RT8454 AC-CC One-Stage Driving Scheme12Application Tip: RT8454Channel Number ExtensionVauxAC to DC Primary Side CircuitOpto-CouplerAC Power Lines13Applications: Isolated E26/27, T5/T8, PAR30/38.Primary side solution examp

10、le1.Flyback: R7912 (MOS inside) R7732(MOS ext.)Low PF, small output current ripple, good efficiency, good for no-PF requirement condition.2.Valley-fill PFC+FlybackFor small power (0.7 application.3.Active PFC+FlybackHigh PF (0.9), lower efficiency, small output current ripple, good for high power de

11、sign.4.PFC single stageHigh PF (0.9), low cost, need big output cap to reduce current ripple. Good for small power, low cost design.5.LLCHigh efficiency, high cost. Good for high power, high performance design.6.Primary side constant current : R7710Current accuracy is suffered from transformer accur

12、acy. Good for current accuracy 90% possible)lCheap and simple external componentslVery wide input voltage range (16V400V or higher)lStable LED current over wide input voltage rangelWorks with standard series drum choke inductorslSupport OVP & OCPlSmall PCB to to fit GU10, E17.19Three RT8458 appl

13、ications1.Typical applicationlAdvantagelVery good line regulation. LED current variation between 110V/220V AC input is minor. (+/-2%)lSmall input/Output caplSimple external componentslGood for application do not need PFC.lDisadvantagelLow PF (About 0.6)2.Valley-fill PFC+RT8458lAdvantagelPF at 0.70.9

14、 for low power application (0.7 designlDisadvantagelBig cap for high power or high PF application.3.Active PF + RT8458lAdvantagelHigh PF (0.95)lGood for high power, high PF designlDisadvantagelHigher costlLower efficiency20RT8458 typical application circuitOVP optionVout31VEMI improvement21High-effi

15、ciency universal input designVin.ac (V)Pin(W)V-LED (V)I-LED (A)Pout (W)Eff. (%)9010.2536.20 0.2579.303 90.76 11010.2236.29 0.2579.327 91.26 13010.2936.19 0.2579.300 90.38 18010.1936.02 0.2579.257 90.85 22010.2136.02 0.2579.257 90.67 26010.2336.06 0.2579.267 90.59 22RT8458 efficiency vs. LEDs LED cur

16、rent=350mA23RT8459 High PF, floating buck LED driver for non-isolated applicationlUnique self-biasing floating buck driver topologylTrue average LED current sense for high PF applicationlCheap and simple external componentslVery wide input voltage range (16V400V or higher)lStable LED current over wi

17、de input voltage range with high PF supportlWorks with standard series drum choke inductorslSupport OVP & OCPlSmall PCB to to fit GU10, E17.24RT8459 typical application circuit25RT8459 test result with universal input* Good line regulation for universal input with high PF support* NOTED: Higher

18、output current ripple & big output cap. for PFC single stage design8459 Vout=44V/200mA/15LEDsVin.ac (V)Vo (V)Io (mA)Pin (W)Po (W)PFEff. (%)current offset (%)9043.33 1949.38.41 0.980 90.39 -1.02%11043.37 1969.268.50 0.981 91.80 0.00%13043.35 1959.198.45 0.985 91.98 -0.51%18043.31 1919.038.27 0.97

19、2 91.61 -2.55%22043.36 1949.238.41 0.955 91.14 -1.02%26443.41 1969.428.51 0.932 90.32 0.00%26How to choose the driving topology?Need PFC?RT8458 typical applicationNOSmall output current ripple?RT8459 typical applicationValley-fill PFC+RT8458 good for small power, PF in 0.70.9Active PFC + RT8458, goo

20、d for high power design or PF0.9NO27DC to CC Solution28Richteks Product - DC to Constant CurrentConverterControllerRT8480RT8452RT8450BRT8482RT8453BRT8470RT8488 Application MR16, AR111 Street light, Desk light, Freeze light Car light, Projector lamp Solar lighting, Emergency lightRT847129Richteks Pro

21、duct - DC to Constant Current Richtek advantage Cover wide input/output voltage range and support different kinds of topology include buck, boost, buck-boost, SEPIC Accurate output current over wide temperature range Stable output current vs. input/output voltage change Easy Dimming : Analog, PWM or

22、 PWM Converting to Analog with One External Capacitor, Triac dimming Support high-speed PWM dimming up to 50kHz Better reliability with bipolar process Cost competitive30Selection Guide for DC to CC ProductsDC Input to Constant CurrentPart NumberVin(V)Max Vout(V)LED current per string (mA)Max Effici

23、ency(%)LED StringTopologyRT8450A4.540+Zener drop50UP to 1.5A 951Buck,Boost,Buck-BoostRT8450B4.540+Zener drop50UP to 1.5A 951Buck,Boost,Buck-BoostRT84524.536+Zener drop48External MOSFET 951Buck,Boost,Buck-BoostRT84534.54038UP to 1.5A 951BuckRT84804.540+Zener dropLimited by external MOSFETExternal MOS

24、FET 931Boost, SEPICRT84824.536+Zener drop48External MOSFET 951Buck,Boost,Buck-BoostRT847073028UP to 1A951BuckRT8488736+Zener dropLimited by external MOSFETExternal MOSFET926Boost31Applications32Applications: MR16 Major solutionsRT8470 low cost solutionLowest cost solutionAbout 70% Electronic Transfo

25、rmer (ET) compatibilityDifferent brightness with different ET connectedVery popular in ChinaRT8453 high ET compatibility solutionVery high ET compatibilityKeep same brightness with different ET connected Special applicationsRT8453 dimmable solutionDimmable with minor cost added from the previous sol

26、utionSame performance as the previous solution without dimmer connectedET limitedWith selected ET, about 50% dimmer can dim pretty wellRT8453 non electrolytic cap solutionHigh ET compatibility with square wave outputRT8453 three-step dimmingSupport three-step dimming with three-step dimming controll

27、er addedUse ON/OFF break to switch between three steps33Application: MR16 (RT8470 BUCK-a typical low cost design)34MR16RT8470 BuckCH1: VinCH4: IinCH1: LED voltageCH4: LED currentAverage LED current will be different with different ET connected35Application: RT8453 MR16Excellent electronic transforme

28、r compatibilityHigh efficiency, stable output LED currentSupport Triac dimming with selected ET and Dimmer but no extra cost addedNo flicker with most of the ET36Application: RT8453 MR16CH1: VinCH4: IinCH1: LED voltageCH4: LED currentVery stable LED current with different ET connected37Applications:

29、 Street Light (I)AC PowerOther Control SignalsMCUNTCSense LED Temp.Gx6VbaseDimFBx6Vaux6 Current SourcesRT8454CSx6.6 CHs.PFC +AC2DCPrimary SideCircuitOpto38Applications : Street Light (II)PFC AC2DCSolar CellLiFePO3 BatteriesAC PowerOther Control SignalsMCUNTCSense LED Temp.Gx6DC 12V48VGateSenseDimFBx

30、6GbiasVaux6 Current SourcesRT8488CSx6.6 CHs.(Either one or both)39Applications : Street Light (III)PFC AC2DCSolar CellLiFePO3 BatteriesAC PowerOther Control SignalsMCUNTCSense LED Temp.Thermal FeedbackDC 12V48VGateSenseDimPWMOGbiasVauxDimmingRT8480Up to 40 xLEDs (160V)IFBCurrent FB(Either one or both)40