Multi-Channel Led Driver With Self-Optimized Active Current Regulator

A novel multi-channel LED driver is presented, consisting of an active current regulator and a switch-mode voltage regulator for each channel. This driver is implemented using a 0.35 mu m 40V high voltage process. The active current regulator directly controls an LED-current without any current-sensing resistor and its operating voltage is self-optimized by the switch-mode voltage regulator. This self-optimization is successfully achieved and the active current regulators have channel-current deviations of a maximum of +/-2%. Its power-conversion efficiency is up to 91% at the load power of 7 W.