The circuit and firmware described in this application
note demonstrates a minimal parts count driver/control-
ler 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 pre-
programmed Flash sequences. The Flash PIC micro-
controller 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. AN874
Buck Configuration High-Power LED Driver
Voltage and Current
Author: Keith Curtis
Microchip Technology Inc. The 1 watt chosen module requires a typical drive of
3.4V at 350 mA to produce its full output brightness.
The maximum current drive for the unit is 500 mA.
INTRODUCTION Exceeding the maximum current specification for the
module, even by short durati……
