A 4-to-42-V Input 3.3-V Output Self-Biased DC–DC Buck Converter Featuring Leakage-Emulated Bootstrap Voltage Refresher and Anti-Deadlock

Abstract

This letter presents a 4-to-42-V input and 3.3-V output dc–dc buck converter for battery-powered automotive uses. Pulse-frequency modulation (PFM) is a common scheme employed to reduce quiescent current (IQ) and mitigate battery drain. However, sustaining the bootstrap voltage (VB) , essential for activating power switches, becomes arduous at elevated temperatures due to significant leakage currents, particularly when the switching frequency is low in no-load scenarios. To address this issue, this letter proposes a leakage-emulating oscillator-based (LEOB) refresher that stabilizes VB , even at temperatures as high as +125 °C. Additionally, an anti-deadlock self-bias supply is presented to further reduce IQ while ensuring fault tolerance. The chip, fabricated in a 180-nm BCD process, exhibits a low IQ of 3.2 μA and a peak efficiency of 95.5% (93.3%) at VIN= 24 V (42 V), with demonstrated stability of VB from −40 °C to +125 °C.