Power supply equipment includes an adapter to convert power from a power source to a DC power for powering an electronic device. The adapter includes circuitry for producing an analog data signal for use by the electronic device to control an amount of power drawn by the device. A cable has an output connector with a plurality of conductors to transfer the DC power and the analog data signal to the electronic device. The connector further includes circuitry to receive a data request from the electronic device and in response transmit a data output which identifies the power supply equipment to the electronic device.