Flash Driver Fires One Or Two LEDs

The LM3553 emerges as the industry’s first high-current LED driver that enables dual LED operation for camera flash functions in mobile phones, PDAs, smart phones, portable scanners, and medical strobe lights. It is a fixed-frequency, step-up dc/dc converter with two regulated current sinks, driving loads up to 1.2A from a single-cell li-ion battery. The device also provides adjustable over-voltage protection circuitry, which allows it to drive two high-current LEDs in a series configuration, maximizing illumination-to-power ratios. To configure the driver for a specific design, there are 128 adjustable flash-current levels and 16 flash-timer durations, accessible via an I2C compatible interface. Other features include time-out protection, an adjustable switch current limit for the use of small inductors with lower saturation currents, a voltage mode offering a 5V rail for backlights and audio amplifiers, GPIO pin, and soft start. Available in a 12-pin LLP, price is $1.20 each/1,000. NATIONAL SEMICONDUCTOR CORP., Santa Clara, CA. (800) 272-9959.