Digital PWM controller and current estimator for a low-power switching converter

This paper describes design and implementation of a digital controller for an experimental low-power converter in a battery-powered system with power management. Multiple operating modes are used to maintain high efficiency over wide ranges of input voltages and loads. A current estimation technique to perform load-dependent mode switching is proposed and tested. A digital PID regulator design example is described, with emphasis on practical limitations imposed by the fixed-point arithmetic and the delay due to sampling and processing.