Architecture and IC implementation of a digital VRM controller

This paper develops the architecture of a digital PWM controller for application in multi-phase voltage regulation modules (VRMs) with passive current sharing. In this context, passive current sharing and VRM transient response are analyzed. A scheme for sensing a combination of the VRM output voltage and output current with a single low-resolution windowed analog-to-digital converter (ADC) is proposed. The architecture and IC implementation of a digital PWM (DPWM) generation module, using a ring-oscillator-MUX scheme, is discussed. Experimental results from a prototype VRM and a partial controller IC implementation are presented.