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Technical Dialogue

External AC-DC Adapters

D01.4 - High Efficiency AC-Adapter Realized by Voltage-Clamper with Mid-Voltage AHB Converter using Synchronous Rectification

Thursday, March 20, 2025
11:30 AM – 1:30 PM ET
Location: Level One, Hall A3
The advent of GaN devices has intensified the competition for miniaturizing AC adapters. Utilizing the high performance of GaN-FET to reduce the size, power supply topologies are transitioning from the traditional flyback circuit to the resonant circuit-based topologies such AHB (Asymmetric Half-bridge Flyback) configurations. Previously a new concept of two converters combining a voltage-clamper circuit with Mid-voltage (Mid-V) AHB converter was proposed, successfully reducing the converter size by half. But faced the issue the efficiency is still same level to the conventional AC-adapters. In this paper, incorporation of a (SR) synchronous rectification circuit in (Mid-V) AHB converter with some optimization of the soft-switching condition is introduced to achieve higher efficiency. The test board was implemented with an input of 150Vdc for (Mid-V) AHB converter, and output of 20Vout/3.25A(65W) at 500kHz. As a result, AHB converter improved the efficiency dramatically from the previous 91% up to 96.4%.