The circuit and firmware described in this application note demonstrate a minimal-parts count driver/controller for a LumiLED LED. The circuit is based on a buck topology switching power supply using the on-chip comparator peripheral within the PIC12F675 microcontroller. Using the attached Flash microcontroller as a control for the driver circuit expands the capability of the circuit to include intensity control, automated intensity compensation for low battery conditions, and the ability to playback preprogrammed 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.