LT3474

The LT^®3474 is a fixed frequency step-down DC/DC converter designed to operate as a constant-current source. An internal sense resistor monitors the output current allowing accurate current regulation, ideal for driving high  current LEDs. High output current accuracy is maintained over a wide current range, from 35mA to 1A, allowing a wide dimming range.

Unique PWM circuitry allows a dimming range of 400:1, avoiding the color shift normally associated with LED current dimming.

The high switching frequency offers several advantages, permitting the use of small inductors and ceramic capacitors. Small inductors combined with the LT3474's 16 lead TSSOP surface mount package save space and cost versus alternative solutions. The constant switching frequency combined with low-impedance ceramic capacitors result in low, predictable output ripple.

With its wide input range of 4V to 36V, the LT3474 regulates a broad array of power sources, from 4-cell batteries and 5V logic rails to unregulated wall transformers, lead acid batteries and distributed power supplies. A current mode PWM architecture provides fast transient response and cycle-by-cycle current limiting. Frequency foldback and thermal shutdown provide additional protection.