the power management integrated circuit has a startup circuit , a switch controller and a standby controller . powered by a power source , the startup circuit provides electric power to an operational power source during a startup period . the switch controller controls a power switch to store or release energy in an energy conversion unit . powered by the power source , the standby controller receives a standby signal . when the standby signal is asserted , the standby controller disables the startup circuit and the switch controller , thereby startup circuit not providing electric power to the operational power source and the switch controller continuously turning off the power switch .