Comparison between Quasi-Resonant and Active Clamp Flyback topologies for GaN-based 65W Wall Charger Application

Abstract

With the growing demand for compact, lighter weight, and low-cost consumer electronics, efficient power conversion with higher switching frequency is being pursued rigorously. This paper demonstrates and compares two high efficiency and high-power density designs of 65W USB Type-C wall charger adopting the quasi-resonant flyback (QRF) and the active clamp flyback (ACF) topologies, respectively. The 650 V 360 mΩ GaN power IC TP44400NM is used as the primary switch in both the designs due to its low output capacitance, low gate charge, and reduced parasitic. In this work, two prototypes of the 65 W USB-PD adapter using the QRF and ACF topologies were designed, fabricated, tested, and experimentally compared to investigate the merits of the topologies for charger application. The comparative power loss distribution for both the converters at full load is analyzed as well. Both of the developed QRF and ACF converters have an uncased power density of ~35 W/in3, peak efficiency of 93.4% and 94% respectively. The designs met European CoC Tier 2 and US DoE Level VI efficiency requirements. The EMI performance of both the chargers passed the EN55022 Class B conducted EMI standard.