Power supply devices are provided that can include power regulating circuitry for regulating (e.g., transforming or converting) electric power to be passed to an electronic device. A power supply device can also include control circuitry coupled with the regulating circuitry. The control circuitry can determine when the power supply device is coupled with an electronic device. The control circuitry can control the operation of the regulating circuitry based on whether or not the power supply device is coupled with the electronic device.