Allegro MicroSystems, Inc. products

The APM80900 and APM80904 are complete synchronous buck switching regulator ClearPower modules that provide constant current for driving high-power LEDs. They integrate both high-side and low-side switches along with the inductor, the input capacitor, and the boot capacitor. Current regulation is achieved on a cycle-by-cycle methodology that utilizes varying the on-time. The maximum output current is easily adapted to the application with the use of an external current sense resistor. The output voltage automatically adjusts to the match the total Vf of the LED string. This ensures the optimal system efficiency. LED dimming is accomplished by a direct logic input pulse width modulation (PWM) signal.