A High Efficiency Step-up WLED Driver with Wide Range PWM Dimming

摘要

A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. An integrated current sensing technique is used to improve system efficiency. Meanwhile, a novel PWM(pulse width modulation) dimming scheme is proposed to achieve wide range dimming frequency, which can be adaptive to dimming frequency from 200Hz to 200 KHz. The proposed driver is designed with CSMC 0.5um 40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized, with a peak value of 94.12% at 5.5V-input and 200mA-load.