Implementation of multi-channel LED driver with low inter-channel current deviation using 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. The active current regulator directly controls an LED current without any current sensing resistor and the switch-mode voltage regulator minimizes a voltage drop at the current regulator, independently for each channel. This is named self-optimization. This LED driver is designed and fabricated through a 0.35μm 2-poly 4-metal 40V high voltage process. The self-optimization is successfully achieved and the active current regulators have current deviations within about ± 2% between the individual channels. It is also confirmed that a power-conversion efficiency of the proposed LED driver is about 87% at the supply voltage of 30V and the channel current of 80mA.