A 92.4% Efficient, 5.5V:0.4-1.2V, FCML Converter with Modified Ripple Injection Control for Fast Transient Response and Capacitor Balancing

Abstract

This paper presents a highly-integrated, 5-level flying capacitor multilevel (FCML) dc-dc converter that uses augmented ripple-injection control to achieve self-startup, fast transient response, and flying capacitor voltage balance. The converter provides 5.5 V:0.4 V-1.2 V step down with robust load- and line-rejection, peak efficiency of 92.4 % and >80 % efficiency at a 13.8:1 conversion ratio with peak current up to 1.4 A. All power devices, bootstrap capacitors, and control functions are integrated on chip; flying and bypass capacitors are die-attached using a custom assembly process.