The LT3474 is a 36-V, 2-MHz stepdown dc/dc converter that operates as a constant-current LED driver.
An internal sense resistor with dimming control drives LED currents up to 1 A with accuracy maintained over a range of 0.035 to 1 A. PWM produces a dimming range of 400:1 without the color shift normally associated with LED current dimming. Input voltage range is from 4 to 36 V. The unit accepts power from a number of sources including four-cell alkaline, NiCd, and NiMH batteries, 5-V logic rails, automotive power systems, and unregulated wall transformers. Switching frequency is settable from 200 kHz to 2 MHz for use with low-value inductors and ceramic capacitors. The chip comes in a thermally enhanced TSSOP-16 package with high side current sensing for grounded-LED cathode connections. An integrated boost diode reduces installation footprint size.
Linear Technology Corp., 1630 McCarthy Blvd., Milpitas, CA 95035, (408) 432-1900, linear.com