Forward-flyback converter for LED driving with reduced number of components

Flyback type converters are widely used in various applications including small power LED drivers. However, they suffer from the losses from the snubber circuit. To beat this problem, previous studies investigated the lossless snubbers. However, they still have a limitation due to the additional components resulting in a high cost and low power density. In this paper, a new converter topology for two-channel LED driving with the reduced number of components. The proposed converter is based on the isolated forward-flyback converter with the blocking capacitors for two-channel output structure. The proposed converter delivers the energy stored in the leakage inductor to the output side directly, whereas conventional approaches store the energy in the additional components. Therefore, the proposed converter can remove the additional snubber components, and it also can achieve a high efficiency. The effectiveness of the proposed converter has been verified with 3.3V input and 11.55W output prototype.