Low Cost, High Power Factor, Dimmable, Monolithic AC-Direct LED Driver with on-Chip Step-Dimmer for Outdoor Lighting Applications

Abstract—In this paper, we develop a monolithic AC LED driver IC which can drive and dim high voltage LED strings directly from the 220V/60Hz commercial AC power. The proposed AC LED driver delivers a best-in-class dimming performance via a simple concept with a step-dimmer, while maintaining a very PF by using a self-adapive power processing circuit. In order to verify the performance of the proposed scheme, a 4.4W, 8-string AC-directly-power LED driver was designed and simulated using 0.35um BCD Magnachip process technology. The simulated results show a PF > 0.99 with a THD < 7% under different dimming modes. The high level of integration and low component count result in a cost-effective solution which is especially suitable for use in outdoor lighting applications.