An apparatus includes a current source rectifier circuit having an input configured to be coupled to an AC power source and an output configured to be coupled to a load, a coupling circuit configured to couple a DC power source to the current source rectifier, and a control circuit configured to selectively operate the current source rectifier circuit and the coupling circuit to generate a DC output from the AC power source and the DC power source. In some embodiments, the control circuit may be configured to operate the coupling circuit to provide a DC/DC converter circuit that uses an energy storage inductor of the current source rectifier circuit. The apparatus may further include a freewheeling diode shared by the current source rectifier circuit and the DC/DC converter circuit. Such apparatus may be used, for example, in DC UPS applications.