This paper presents a high-efficiency GaN-based 65 W Quasi-Resonant (QR) Flyback converter. The converter is characterized by a wide input voltage range and a variable output voltage, and it is designed as a Switch Mode Power Supply (SMPS) for high power density USP-Power Delivery (USB-PD) applications. To increase the efficiency and power density, a regenerative snubber clamp solution has been used to limit the excursion of the drain voltage during the power switch turn-off. The activity involved the modeling of the converter, the sizing of the regenerative snubber, and the design of the flyback transformer. Furthermore, a dedicated test application board was used to verify the effectiveness of the solution. The results were compared with those obtained using a flyback converter with an RCD snubber.

This paper presents a novel technique for controlling the Power Factor Correction (PFC) of a two-stage converter. The proposed solution operates the PFC in a special intermittent mode at a medium or light load. As a result, the flyback converter stage can be optimized to operate within a tight input voltage range, thus obtaining better efficiency and more compactness compared to a traditionally controlled two-stage converter. Circuit models of the converter have been developed to test the goodness of the proposed solution.