A method comprises determining an operating mode based upon an input voltage and an output voltage of a resonant converter, wherein the resonant converter comprises a switch network coupled to an input dc power source, a resonant tank coupled to the switch network and a transformer coupled between the resonant tank and a secondary rectifier, wherein the secondary rectifier is a full-bridge rectifier, configuring the switch network to operate at a buck converter mode in response to a first input voltage and configuring the secondary rectifier to operate at a boost converter mode in response to a second input voltage, wherein the first voltage is higher than the output voltage and the second voltage is lower than the output voltage.