Quasi-Parallel Voltage Regulator Topology for Powering Laptop Processors

Abstract

This paper presents a quasi-parallel voltage regulator topology that is suitable as a laptop processor power supply where the input voltage varies over a wide range. It consists of a phase shift full bridge converter and a buck converter, whose inputs are connected in series to divide the total input voltage and the outputs are connected in parallel to share the load current. The output voltage is regulated with fast dynamics against load change and input voltage variation while the input voltage to the buck converter is also regulated at a relatively low value to improve the overall system efficiency. Different methods to improve the converter efficiency further at both light and high loads are also proposed. The efficiency of the converter at different load currents and input voltages are obtained from a laboratory prototype demonstrating a maximum efficiency of 90.8% at an output voltage of 1.2 V. A small signal model of the converter is then presented and a design methodology for a decoupled controller is discussed. Transient performance of the converter using this controller against 50 A load current change is found to comply with the specifications for a laptop processor power supply.