A regulator circuit, embedded in a device, which is adapted to draw power from a power source internal to the device and a power source external to the device. The regulator circuit includes a first circuit segment for regulating power supplied by the internal power source, a second circuit segment for regulating power supplied by the external power source, an output circuit segment that monitors the output of the regulator circuit and supplies regulated power to the device. Additionally, responsive to the monitoring the regulator circuit preferentially draws power from the second circuit segment and complements the drawn power with power from the first circuit segment to maintain a regulated power supply at the output.