Article ID: 11.20141011
A novel auxiliary-free zero crossing detection (ZCD) circuit is presented in this paper, which is especially suitable for step down non-isolated LED drivers operating in boundary conduction mode (BCM). Without extra auxiliary winding, the proposed method can fast and correctly detect zero inductor current information, which only requires an integrated NMOS power switch. The step down non-isolated LED driver with the proposed ZCD scheme has been implemented in CZ6H 0.35um standard CMOS process, results show that the proposed ZCD scheme can always work properly regardless of the variation of line voltage and load condition.