SC4539 Datasheet | SEMTECH

High Efficiency Boost Converter for up to 6 LEDS POWER MANAGEMENT Features Input voltage range - 2.8V to 5.5V Current-mode PWM control - 800k Hz - Programmable LED current up to 30m A - Soft-start to reduce in-rush current - PWM dimming - 100Hz to 50k Hz - PWM dimming at ISET - Analog and filtered - Over-voltage protection - 25V (max.) .. - Under-voltage lockout (UVLO) - Thermal shutdown - Shutdown current - <1μA - Ultra-thin package - 2mm x 2mm x 0.6mm - Lead-free package, WEEE and Ro HS pliant - - Description The SC4539 is designed to regulate current for a series chain of white LEDs in LCD backlighting applications where small size and high efficiency are priorities. This device integrates an 800k Hz current-mode PWM boost converter and a 30m A programmable low dropout current sink regulator. An external resistor sets the LED current up to 30m A. PWM dimming (100Hz to 50k Hz) may be applied directly to the enable (EN) pin, or dimming can be controlled by applying an analog signal to the ISET circuit. The boost circuit can output up to 22V (guaranteed) to drive up to 6 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 high leakage. Under-voltage lockout and thermal shutdown provide additional protection. A small external capacitor and series resistor control soft-start and loop pensation. Over-voltage detection protects the SC4539 if the LED pin is floating or shorted to ground. The SC4539 is available in an MLPD-8 pin 2mm x 2mm x 0.6mm package, with a rated temperature range of -40°C to +85°C. Applications - - - - - White LED Display Backlight Driver Smartphones and PDAs Cellular Handsets MP3 and Portable Media Players DSC, GPS, Satellite Radio, Game Players Typical Application Circuit D L1 LX IN CIN OUT COUT 2.8 to...