A Single-Stage Primary-Side-Controlled Off-line Flyback LED Driver with Ripple Cancellation

Ripple cancellation LED driver can achieve flicker-free LED driving while maintaining high power factor, high efficiency, and low component cost. It is a very competitive solution compared to a conventional single-stage or two-stage LED driver design. In this paper, a primary-side-controlled ripple cancellation LED driver has been proposed. The voltages of the proposed LED driver are sensed at the primary side by transformer sensing windings. The LED current is also obtained by sensing the primary-side switching current. The entire control circuit is built on the primary side. All the advantages from the existing ripple cancellation LED drivers are maintained while achieving the primary-side control. Based on the proposed circuit, a potential integrated primary-side controller can be designed, which can significantly reduce the component cost and design complexity. A 30-W, 50-V, 0.6-A experimental prototype with a universal input voltage range has been built to verify the proposed LED driver.