Cross-Coupled Series-Capacitor Quadruple Step-Down Buck Converter

Abstract

This paper introduces a novel two-phase dc-dc multi-level flying capacitor converter topology. This topology is well-suited for emerging high step-down applications. It features both natural balancing of the inductor phase currents as well as inherent flying capacitor voltage stabilisation. The switching node voltage swing reduction of $\frac{{{V_g}}}{4}$ is achieved with the same number of switches required by the 5-level multi-level flying capacitor buck, which does not have inherent balancing features, and the 4-phase series capacitor buck which requires components with higher voltage ratings. The functionality of the topology is demonstrated with a prototype with peak operating efficiencies of 94.5% for 48V-to-1V operation and 95.9% for 24V-to-1V operation.