SC4538 Datasheet | SEMTECH

High Efficiency Boost Converter for up to 10 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 - Analog and filtered-PWM dimming at ISET - Over-voltage protection - 38V (min.) .. - 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 SC4538 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 SC4538 drives a string of up to 10 white LEDs with a forward voltage of 3.8V or less. 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 SC4538 if the LED pin is floating or shorted to ground. The SC4538 is available in an MLPD-8 pin 2mmx 2xmm 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 2.8 to 5.5V LX...