A Dynamic Model of Switched-Capacitor Power Converters

Switched-capacitor (SC) converters are frequently used for low-power applications that require little or no output regulation. Previous work has established static SC converter models, essentially composed of an ideal transformer (with turns ratio determined by the topology) and an output resistance that varies with component choices, switching frequency, and duty ratio. In this paper, the static model is expanded to include the dynamic response to the input voltage and output current changes. The dynamic model is particularly important in systems that experience large output power transients, such as low-power systems that enter and exit sleep modes. For applications that are only concerned with input-output behavior, a reduced-order model that neglects internal dynamics is derived. The dynamic model is validated with both simulations and experimental results.