A power converter capable of providing a range of DC voltages to an external device and a method of providing a range of DC power are provided. The power converter comprises a supply circuit for receiving a request for DC power and for providing the requested DC power. The supply circuit comprises a detection circuit for sensing a connection to an external device, a source controller circuit for determining a DC output power required by the external device, and a converter circuit for generating the required DC output power. The external device comprises a device controller circuit for communicating the request for DC power. A first conductor provides a path for the device to communicate the required DC power to the power converter and for the power converter to supply the required DC power. A second conductor provides a common reference for conducting return current to the power converter.