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Power Management for LEDs

Power Management for LEDs
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LEDs Key Advantages of LEDs and Their Operation Versus Alternative Lighting Sources A light-emitting diode (LED) is a semiconductor device that emits narrow-spectrum incoherent light when forward-biased. The color of the emitted light depends on the chemical composition of the semiconductor material used, and can be near-ultraviolet, visible or infrared. LEDs are more prevalent today than ever before, replacing traditional incandescent and fluorescent bulbs in many lighting applications. Incandescents use a heated filament, are subject to breakage and burn- out and operate at a luminous...

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Inductorless charge pump-based Buck, Boost, Buck-Boost designs (these generally drive a single LED or LED strings in parallel): > LED currents range from a few milliamps to 1A > Average efficiencies over the Li-Ion battery range in excess of 80% > Drivers act as constant current sources > Very small solution footprints ideal for handheld devicesDeciding which IC and topology to use depends on the following factors: > The relation of LED(s) forward voltage to the input voltage range: Buck, Boost, Buck-Boost, SEPIC or Flyback > Efficiency ֖ crucial for driving high brightness (HB) LEDs while...

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03 07MEDIUM TO HIGH CURRENT (100mA TO 2A) LED DRIVERS FOR PHOTOFLASH/TORCH LIGHTING V > IN SW1SW2V > OUT LED EN2 EN1 I > LED LEDV 0 0 0 (SHUTDOWN) 0 1 150mA 1 0 850mA 1 1 1A LTC3454 EN2 (FLASH)EN1 (TORCH) V > C I > SET1 0.1յFR I > ISET1 GND (EXPOSED PAD) > SET2 20.5k1%R > ISET2 3.65k1% > * Output voltage and current depend on the choice of external components 04109 CS3_LIN_LED_FA_10Ֆ708.r2.indd 10 04109 CS3_LIN_LED_FA_10֖708.r2.indd 10 10/24/08 3:43:57 PM 10/24/08 3:43:57 PM size="-2">

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02 08 HIGH CURRENT LED DRIVERS FOR CAMERA FLASH/TORCH INDUCTORLESS 2.2F2.2յF 2.9V TO 4.5V V > IN CPOGNDENF 4.7FLEDAOT2015 LTC3218 > EFFICIENCY (%) I ENABLEDDISABLED > LED ENABLEDDISABLED ENTCPCM I > SETF I > SETT 40507080 90100 6050mA150mA 300mA 2.94.53.33.74.13.13.53.94.3 ENF0 0 1 10 (SHUTDOWN)100mA (TORCH) 290mA 390mA (FLASH)I ENT0 1 0 1 > LED V > IN (V) 10.2k 1% > * Flash Mode** Dependent on V IN , V LED , I LED 04109 CS3_LIN_LED_FA_107֖08.r2.indd 11 04109 CS3_LIN_LED_FA_107֖08.r2.indd 11 10/24/08 3:43:57 PM 10/24/08 3:43:57 PM size="-1">

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03 09MEDIUM CURRENT (100mA TO 350mA) LED DRIVERS BUCK LED 10095 90 607570 658085 5550201224 50/500mA Two Series Red LED Driver V > IN 7V TO 32V V > IN BOOSTSWDACAPOUTV F 0.1 յ F 10 H 51k LT3592 > EFFICIENCY (%) +200/20mVՖ ONBRAKE140k900kHz SHDNBRIGHT R 0.4 7 4.7 F1 > T 28168 BRIGHT 500mA GND > FB INPUT VOLTAGE (V)4 10k >

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03 11MEDIUM CURRENT (100mA TO 350mA) LED DRIVERS BUCK-BOOST EFFICIENCY (%) D1L14.3H > IN 8V TO 16VV C50.22յF PWM DUTY CYCLE (%)0 708090 80 6050204060100403020 SHDN V > IN SW PWM LT3518 R > SENSE REF 330m 7 C1 2.2F CTRLSYNC300mAV C2 4.7յF R13.92MR2124kM1 > C T SSR GNDR > T 6.04k2MHzC30.1F C40.1յF PWMISPFBISNTGTGENV > * I OUT ~ 0.65 I SW x (V IN / V OUT ). Estimate: may vary depending on external component selection. 04109 CS3_LIN_LED_FA_10֖708.r2.indd 14 04109 CS3_LIN_LED_FA_10֖708.r2.indd 14 10/24/08 3:43:59 PM 10/24/08 3:43:59 PM size="-2">

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02 12 LOW TO MEDIUM CURRENT (20-200mA/LED) MULTIDISPLAY LED DRIVERS INDUCTOR BASED EFFICIENCYLED CURRENTV 12V (TYP)9V TO 15V C > IN 10F > LED CURRENT (mA) C C > EFFICIENCY (%) OUT1 OUT2 2.2 յ F C1 1FL110յHL210H V 2.2 յ F > 657075808590 020 406080100120 20406080 IN = 12V8/8 LEDs SW1SW2 V > 100 IN LUXEONLEDsLXCL-PWF1LUXEONLEDs LXCL-PWF1C > PWM DUTY CYCLE (%)060 OVP2CTRL2REFPWM2FB2OVP1CTRL1SHDNPWM1FB1 > IN V > IN LT3486 100mAOFF ON D1 Q1100k100k3.65k3.65k21.5kQ2 5VD2 > REF 100mAPWMFREQ 1kHzR 0.1F V > C1 GNDV R > T C2 DIMMINGINPUT 1 DIMMING INPUT 2 PWMFREQ 1kHz 2.2nF22pF2.2nF > * Dependent on...

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03 13LOW CURRENT (20mA TO 50mA) LED DRIVERS BUCK 1F 50mA VREGSWLEDGND 4 > 7 V > IN 48V 708090 3050605040 > IN EFFICIENCY (%) CONTROL CTRLV 470յH LT3590 0.1F1յF 102040 100 LED CURRENT (mA)0 >

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02 14 LOW CURRENT (20mA TO 50mA) LED DRIVERS BOOST IN 3V TO 5VSHUTDOWN ANDCURRENT CONTROLSWCAPLEDGND 1 յ F 1 F > IN LT3593 > EFFI CIENCY (%) CTRLV 20155 V LED CURRENT (mA)0 > * I OUT ~ 0.65 I SW x (V IN / V OUT ). Estimate: may vary depending on external component selection. 04109 CS3_LIN_LED_FA_107֖08.r2.indd 17 04109 CS3_LIN_LED_FA_107֖08.r2.indd 17 10/24/08 3:44:01 PM 10/24/08 3:44:01 PM size="-2">

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03 15MULTICHANNEL LED DRIVERS FOR LARGE LCD PANELS (30mA TO 50mA) LED Driver for 60 White LEDs V > IN IN SWV V > OUT V > O_SW 2M FBOPENLEDPWMSHDNRTSYNCCTRLV PWMSHDNSYNC 61.9k LT3598 > REF LED1LED2 LED3 LED4 LED5 LED6 10k10k 100k 43k > SET I > SET SSGNDT V > C 3.01k 2.2ֵF10H4.7յF 10nF20mA 80k 10k10nF > 04109 CS3_LIN_LED_FA_107֖08.r2.indd 18 04109 CS3_LIN_LED_FA_107֖08.r2.indd 18 10/24/08 3:44:01 PM 10/24/08 3:44:01 PM size="-2">

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03 17LOW CURRENT MULTIDISPLAY LED DRIVERS INDUCTORLESS * Serial Peripheral Interface** High Current Camera LED >=200-425mA *** Dependent on V Different I 2 C address ++ Red, Green, Blue LEDs IN , V LED , I LED+ 04109 CS3_LIN_LED_FA_107֖08.r2.indd 20 04109 CS3_LIN_LED_FA_107֖08.r2.indd 20 10/24/08 3:44:03 PM 10/24/08 3:44:03 PM size="-1">

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02 18 LOW CURRENT GENERAL PURPOSE LED DRIVERS INDUCTORLESS OUTPUT RIPPLE (mVp-p) 510152030 255075100 125150 LOAD CURRENT (mA)00 > C > Ֆ C > + DRIVE UP TO 5 LEDS 3V TO 4.2VLi-IonBATTERY V > IN V > OUT 2.2 F+ LTC3204-5/LTC3204B-5 2.2 յ F 7 100 7 100 7 100 7 100 7 ONOFFV SHDN 2.2 GND (APPLY PWM WAVEFORM FORADJUSTABLE BRIGHTNESS CONTROL)t100 > SHDN * Burst Mode Operation** Dependent on V IN , V LED , I LED 04109 CS3_LIN_LED_FA_10Ζ708.r2.indd 21 04109 CS3_LIN_LED_FA_10֖708.r2.indd 21 10/24/08 3:44:03 PM 10/24/08 3:44:03 PM size="-2">

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03 19ORGANIC LED (OLED) BIAS LOW TO HIGH CURRENT (50mA TO 2A) DRIVERS IN IN = 3.6V LOAD FROMCAPACITORLOAD FROMV > IN H 3VTO 4.2VV 7080 90 11010050403020 160200240 280 12080400 V > POWER LOSS (mW) OUT յ F 0.22 > FV SWCAPV > OUT CC OUT 16V16mA LT3494 2.21M4.7 > EFFICIENCY (%) SHDNCTRLV FBGND 2.2 > յ F15 LOAD CURRENT (mA)0.1 60 > * I OUT ~ 0.65 I SW x (V IN / V OUT ). Estimate: may vary depending on external component selection. 04109 CS3_LIN_LED_FA_10і708.r2.indd 22 04109 CS3_LIN_LED_FA_10֖708.r2.indd 22 10/24/08 3:44:04 PM 10/24/08 3:44:04 PM size="-1">

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