A 3-to-40-V Automotive-Use GaN Driver With Active Bootstrap Balancing and VSW Dual-Edge Dead-Time

Abstract

This article presents a GaN driver operating at a switching frequency variable from 10 to 30 MHz to achieve reliable and efficient power conversion for automotive electron- ics applications. An active bootstrap (BST) balancing (ABB) technique is presented to stabilize the BST rail voltage by sensing V SW and controlling BST rail charging. Meanwhile, a VSW dual-edge dead-time ( tdead) modulation senses instant VIN and IO and generates optimal tdead for VSW trailing and leading edges, achieving zero-voltage switching (ZVS) turn-on for GaN power switches. To operate at high frequency and retain high efficiency, pulse-based dynamic up- and down-level shifters are developed to achieve sub-nanosecond propagation delay with a quiescent current of 0.5 µA. To validate this work, a switching power converter prototype is implemented using a 0.35- µmh i g h - voltage (HV) BCD process. It maintains a constant 5.1-V BST rail voltage to prevent GaN FET from destructive breakdown and accomplishes 0.9-to-3.7-ns t dead and 3.7-to-10.4-ns tdead for VSW trailing and leading edge, respectively, in response to load current IO change from 0.01 to 1.2 A. The proposed techniques jointly improve the efficiency by 8.3%, which peaks at 90.7% for 12-to-5-V conversion and 88% for 40-to-5-V conversion.