SC4539ULTRT Semtech

SC4539 High Effi ciency Boost Converter for up to 6 LEDS POWER MANAGEMENT Features Description Input voltage range 2.8V to 5.5V The SC4539 is designed to regulate current for a series Programmable LED current up to 30mA string of white LEDs in LCD backlighting applications Current-mode PWM control 800kHz where small size and high effi ciency are priorities. This Soft-start to reduce in-rush current device integrates an 800kHz current-mode PWM boost PWM dimming 100Hz to 50kHz converter and a 30mA programmable low dropout current PWM dimming at ISET Analog and fi ltered sink regulator. Over-voltage protection 22V (minimum) An external resistor sets the LED current up to 30mA. Under-voltage lockout (UVLO) PWM dimming (100Hz to 50kHz) may be applied directly Thermal shutdown to the enable (EN) pin, or dimming can be controlled by Shutdown current <0.1A (typical) applying an analog signal to the ISET circuit. The boost Ultra-thin package 2mm x 2mm x 0.6mm circuit can output up to 22V (guaranteed) to drive up to 6 Lead-free package, WEEE and RoHS compliant LEDs in series. The current regulator protects against shorts between the BL and OUT pins and also eliminates backlight glow during shutdown when using LEDs with Applications high leakage. Under-voltage lockout and thermal shut- DSLR, DSC, and Video Cameras down provide additional protection. A small external Cellular handsets capacitor and series resistor control soft-start and loop Portable media players compensation. Over-voltage detection protects the Personal navigation systems SC4539 if the BL pin is fl oating or shorted to ground. Satellite radio The SC4539 is available in an MLPD-8 pin 2mm x 2mm x Handheld video games 0.6mm package, with a rated temperature range of -40C to +85C. Typical Application Circuit D L1 LX C OUT 2.8 to 5.5V IN OUT C IN SC4539 Enable and EN PWM dimming R ISET ISET C COMP R COMP COMP BL GND June 20, 2008 2008 Semtech Corporation 1SC4539 Pin Confi guration Ordering Information Device Package (1) (2) SC4539ULTRT MLPD-UT-8 2x2 SC4539EVB Evaluation Board Note: LX 1 8 IN (1) Available in tape and reel only. A reel contains 3,000 devices. TOP (2) Lead-free package only. Device is WEEE and RoHS compliant. VIEW 2 7 EN GND ISET 3 6 BL 4 5 OUT COMP T MLPD: 2mm x 2mm 8 Lead = 74C/W JA Marking Information FF0 yw FF0 = Marking code for SC4539 yw = Date Code 2