A novel over-current protection circuit for LED constant current driver

This paper presents a novel over-current protection circuit applied in constant current driver for LED. The circuit uses SENSEFET current sensing technique to sample inductor current, which has a high accuracy. It is different with the traditional over-current protection circuit, which uses voltage comparator. Current comparator, applied in this circuit, has simple structure and quick response. This over-current protection circuit has been successfully applied to a step-down constant current LED driver chip, and has been implemented with TSMC 0.25μm 40V BCD process. Simulation results show that the sampled current accuracy is 98.68%, meeting the accuracy requirements.