Buck Configuration High-Power LED Driver

The circuit and firmware described in this application note demonstrates a minimal parts count driver/controller for a high-power (1W or greater) LED. The circuit is based on a buck topology switching power supply using the on-chip comparator peripheral within the PIC12F675 PIC® microcontroller. The switching power supply design ensures efficient power transfer between the system battery and the output LED. The Flash PIC microcontroller is used to implement intensity control, automated intensity compensation for low battery conditions, and the ability to playback preprogrammed Flash sequences. The Flash PIC microcontroller also allows the creation of a custom PC-based graphical user interface, using the PICkit™ 1 Flash Starter Kit for programming the pre-programmed Flash sequences. The combination of the switching power supply design and the microcontroller results in an efficient circuit with advanced automated features while keeping the circuit simple and inexpensive.