A power supply includes a first amplifier, a first current stage, and a second current stage. The first amplifier is configured to set an output voltage equal to a fixed input voltage for supplying to a device. The first current stage is configured to source and sink a first range of first output currents and provide a first measurement current representing a first output current. The second current stage is configured to source and sink a second range of second output currents and provide a second measurement current representing a second output current in response to the first range being exceeded. The first output current and the second output current are summed for supplying to the device. The first measurement current and the second measurement current are summed at a node.