HY7700 is a PWM high-efficiency LED driver controller IC. It allows efficient operation of High Brightness （HB） LED(s) from voltage sources ranging from 9VDC up to 450VDC. HY7700 controls an external MOSFET at variable switching frequency up to 300 kHz. The constant off-time can be programmed using a single resistor. The LED string is driven at constant current rather than constant voltage, thus providing constant light output and enhanced reliability. The output current can be programmed between a few milliamps and up to more than 1.0A