LT3755

The LT^®3755 and LT3755-1 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 7V supply. The fi xed 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 100kHz to 1MHz to optimize effi ciency, performance or external component size.

The LT3755/LT3755-1 sense output current at the high side of the LED string. High side current sensing is the most fl exible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode confi guration. 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 (3mm × 3mm) QFN and MSOP packages.