Digital Zero-Current Switching Lock-In Controller IC for Optimized Operation of Resonant SCC

This article introduces a lock-in integrated controller for resonant switched-capacitor converter (SCC). The controller identifies the resonant period of each subcircuit on-the-fly and locks-in to the correct switching time to fully utilize the charge transfer rate for each flying capacitor. The various modules of the controller are detailed, including the autotuner and sequencer, which accommodate any mismatch, variations or drifts of component values or circuit configuration. The integrated circuit (IC) has been designed and fabricated on a 0.18 μm 5 V process resulting in effective silicon area of 0.64 mm2. Experimental results of the controller IC operating in closed-loop are provided, demonstrating accurate lock-in for two resonators with individual independent resonant characteristics. A full-scale hardware prototype of 650 W 4:1 switched-tank-converter is used to validate the controller's operation, demonstrating excellent lock-in capabilities resulting in high efficiency of up to 98.6%.