High efficiency LED driver featuring auto output-voltage tuning
This paper presents a high efficiency LED driver that employs a current-mode buck regulator to energize four linear constant-current regulators. An auto-tuning procedure is introduced in to adjust the output voltage of buck regulator, which keeps the dropout voltage of the passive devices in linear regulators at a possible minimum level while maintaining high performance. Thus, the conversion efficiency of the linear regulator is maximized and so is the overall efficiency. A prototype of the high efficiency LED driver was designed with a standard 0.35µm CMOS process. The simulation results show that the expectant functions are well achieved.