A Power-compensated and Dimmable AC Direct LED Driver with High Efficiency

作者：Gu, Donglie; Tang, Shengpeng; Sun, Kexu; Xi, Jianxiong; He, Lenian^*

来源：Journal of Semiconductor Technology and Science, 2017, 17(6): 750-764.

DOI：10.5573/JSTS.2017.17.6.750

• AC direct LED driver
• soft self-commutating
• low frequency pulse-width modulation dimming
• power compensation
• high efficiency

A dimmable and power-compensated AC direct LED driver for lighting application is presented. A Source-Coupled Pair (SCP) is adopted to realize the soft self-commutating. To maximize the power efficiency, a multi-dimensional optimization method is applied for finding the optimum number of LEDs in each string. Moreover, error analysis for efficiency is introduced to evaluate the impact of circuit mismatches on efficiency. The driver includes a Power Compensation module which enables the LEDs power approximately constant under various AC line voltages. In addition, a low frequency pulse-width modulation (LFPWM) dimming technique is designed to regulate the LED's brightness. The LED driver IC is designed and implemented in CSMC 700 V 1 um BCD process. The post-layout simulation results show that the system can achieve a high efficiency of 90.2% under typical condition and 220 V vertical bar rms, meanwhile realize dimming with a 90% duty cycle, 10 kHz dimming signal. With the proposed compensation scheme, the output power only changes less than 5% under 20% variation in input voltage.

• 出版日期2017-12
• 单位浙江大学