A power supply includes a power conversion circuit configured to selectively operate in one of an active mode in which output power is supplied to a load and a standby mode in which output power is not supplied to the load, a plurality of auxiliary circuits including a first auxiliary circuit and a second auxiliary circuit, a bias node configured to supply power to the plurality of auxiliary circuits, and a switch that is coupled between the bias node and the first auxiliary circuit and that is configured to disconnect the first auxiliary circuit from the bias node in response to a control signal.