Transient current regulation using a single DC-DC converter for high-efficiency RGB LEDs

This paper presents a dual-current regulating solution for a 3W light-emitting diode (LED) driver. This is useful for systems that use a single DC-DC converter driving multiple LEDs (e.g., interleaving red, green, and blue LEDs) to generate the full color range. When switching from blue to red, variations in LED forward voltage will cause a transient current spike of 1.5A for a desired steady state current of 300mA. Utilization of our work´s dual current regulation reduces the transient current spike to as little as 10% overshoot of the desired steady state current, which has not been accomplished in previous works to the authors´ knowledge. This regulation technique requires no extra control circuitry with minimal added design complexity, and only draws additional power when it is in use at LED transitions, allowing the system to operate at above 90% efficiency as suggested by SPICE simulations.