Multi-Mode Operation of Resonant Switched Capacitor Converters for Optimized Efficiency

Resonant switched capacitor (ReSC) converters are a promising alternative to traditional magnetic (buck and boost) and switched capacitor (SC) converters due to favorable tradeoffs between passive component size (power density) and efficiency. Operating ReSC converters with variable frequency in continuous- or discontinuous-current mode (CCM or DCM) has been shown to improve efficiency both at low and high loads. No closed form solution exists that determines the optimal operating mode and frequency based on the load current. This paper derives such a solution for the nominally 2:1 architecture and highlights the reduction in power loss that is achievable with optimized multimode operation compared to operation at a fixed frequency. The proposed approach is verified in a hardware prototype.