Linear Technology's LT3756 and LT3756-1 are DC / DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7 V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages.

A ground referenced voltage FB pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100 kHz to 1 MHz to optimize efficiency, performance or external component size.

The LT3756/LT3756-1 sense output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability. Both parts are available in the 16-lead QFN (3 mm x 3 mm) and MSOP packages.