DC1166A: 500mA @ 55V Max, 4.5 ~ 55V in, Buck

Demonstration circuit 1166 is a 48V Buck-Mode LED Driver featuring the LT3590. The LT3590 is a fixed frequency buck mode converter specifically designed to drive up to 10 LEDs in series from a 48V DC source. Series connection of the LEDs provides identical LED currents of up to 50mA, resulting in uniform brightness and eliminating the need for ballast resistors. A fixed frequency current mode architecture results in stable operation over a wide range of input voltage and load condition. The high switching frequency allows using tiny components for the circuit.

The LT3590 datasheet gives complete descriptions of the part, operation and application information.
The datasheet must be read in conjunction with this quick start guide for working on or modifying the demo circuit 1166.