DESCRIPTION
The LT®3475/LT3475-1 are dual step-down DC/DC converters 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. The high side current sense allows grounded cathode LED operation. High output current accuracy is maintained over a wide current range, from 50mA to 1.5A, allowing a wide dimming range. Unique PWM circuitry allows a dimming range of 3000:1, avoiding the color shift normally associated with LED current dimming.

FEATURES
■ True Color PWMTM Delivers Constant Color with 3000:1 Dimming Range
■ Wide Input Range: 4V to 36V Operating, 40V Maximum
■ Accurate and Adjustable Control of LED Current from 50mA to 1.5A
■ High Side Current Sense Allows Grounded Cathode LED Operation
■ Open LED (LT3475) and Short Circuit Protection
■ LT3475-1 Drives LED Strings Up to 25V
■ Accurate and Adjustable 200kHz to 2MHz Switching Frequency
■ Anti-Phase Switching Reduces Ripple
■ Uses Small Inductors and Ceramic Capacitors
■ Available in the Compact 20-Lead TSSOP Thermally Enhanced Surface Mount Package

APPLICATIONS
■ Automotive and Avionic Lighting
■ Architectural Detail Lighting
■ Display Backlighting
■ Constant-Current Sources