One-comparator counter-based controller for synchronous DC/DC converters

A low complexity, low component-count digital controller consisting of a single comparator and a digital counter is proposed for the purpose of providing control and voltage regulation for synchronous buck DC/DC converters used in voltage ripple insensitive applications. The system is modelled and analysed based on an averaged-circuit representation of the buck converter including the parasitic resistances of its passive and active components. The existence of limit cycles is investigated by using a describing function to represent the comparator and the pulse-width modulated generator. The simulation results are presented and are verified with experimental results for a 36 W prototype. The validity of the predicted performance of the proposed controller for higher loading conditions is thus confirmed.