Design of multiple-output step-up/down switching DC-DC converter with vestigial current control

Abstract

A single-chip multiple-output DC-DC converter that uses vestigial-current-control method is implemented in 0.5um BiCMOS occupying $3.6mm^2$. Compared with the prior multiple-output DC-DC converters, this proposed converter can generate multiple-output higher or lower than the input voltage. It consists of 3 step-up/down outputs, 2 step-up outputs, and 1 auxiliary output, and operates stably under wide load variation with simple control loop compensation. The implemented converter operates at 1MHz switching frequency with 4.7uH inductor and 10uF capacitor. In implementing the proposed control method, fast and accurate peak and zero current sensing circuitries are used and verified by experiment. Also, new fast comparators are adopted. The measured efficiency is higher than 83\% while delivering load power of 1.5W