Peak offsetting based CPM controller for multi-level flying capacitor converters

This paper introduces a practical mixed-signal peak current programmed mode (CPM) controller suitable for emerging low-power dc-dc multi-level flying capacitor (ML-FC) converters. The controller eliminates the inherent instability problem of ML-FC converters associated with flying capacitor voltage runaway. The method is based on separate asymmetrical thresholds defining multiple inductor current peaks within one switching period. The effectiveness of the controller is verified through simulations and with a low-power 12 V to 1.8 V/1A, 3-level ML-FC experimental prototype.