A 2MHz Constant-Frequency AOT V2 Buck Converter with Adaptive Dead Time Control for Data Centers

GaN-based Adaptive-On-Time (AOT) V² buck converter is getting more attention for the applications as data center power supply because of its fast transient response and high efficiency. However, in high-frequency and high step-down Buck converters, the frequency deviation and the dead time power loss become serious problems. In this paper, a GaN-based AOT V² buck converter that adopts a high-accuracy on-time generator and successive feedback regulation with capacitive-scaling dead time control is presented. Designed by using CSMC high voltage 0.25 um process, the controller IC can enable a 100 W (5 V/20 A) buck converter to operate at power switch frequency of 2 MHz and adaptively adjust the dead time under various conditions. With the proposed on-time and dead time control, the frequency variation is only 4% and reverse conduction length of GaN devices is less than 2 ns. The input range of this converter is from 12 V to 60 V and the peak efficiency is 90% at 48 V typical input.