Flyback transformer based transient suppression method for digitally controlled buck converters

A current-programmed mode (CPM) digitally controlled buck converter with a flyback transformer is proposed in this work. It achieves fast and smooth dynamic response with a smaller area and volume penalty than most of the other augmented converter solutions. During load transient recovery, current slew-rate of the power inductor is boosted to suppress voltage deviation with the help of the secondary winding of a flyback transformer and three small auxiliary switches. Since the auxiliary switches are not in the main power conduction path and only need to handle occasional current pulses, their size can be minimized without degrading the conversion efficiency. Experimental results with a 6V-to-1V, 3W prototype show a 50% reduction in peak voltage deviation when comparing to a conventional CPM buck converter.