Discontinuous conduction mode of multi-level flying capacitor DC-DC converters and light-load digital controller

A comprehensive analysis of step-down multi-level flying capacitor converters in discontinuous conduction mode of operation is presented, with the main goal of improving light-load power processing efficiency. In addition to that, a novel controller architecture is introduced for the operation of the converter under light-load conditions. In particular, controller artificially creates inductor current ripple around zero-current ripple operating regions enabling discontinuous conduction mode over full range of the conversion ratios. Experimental results obtained with wide input 6-12 V, wide output voltage 1 V-5.5 V, 10 mA <; I_OUT <; 3 A, 20 KHz <; fs <; 500 KHz discrete prototype are presented, showing up to a 50% improvement of efficiency under light-load of operation.