Reduction of output capacitance in dc-dc converters using anticipated load transients

Abstract

This paper presents a control strategy for low-voltage high-current microprocessor applications. The proposed idea supposes that computer-based loads could possibly provide an indicator to the power supply that a transient is soon to occur. It is shown that if such information is available, then it is possible to reduce the size of the bulk filter capacitance. The proposed anticipatory control tightly maintains output voltage of the converter within the required output voltage ripple band during transients. The proposed technique uses a temporary ballast load to precharge the inductor. Therefore, the dynamic response of the converter to the load changes is fast. A 12/1.5-V, 25-A dc-dc converter is used to validate this concept.Index Terms-Anticipatory control, dc-dc converter, microprocessor, load transient analysis, voltage regulator module (VRM).