Patent ID: 8604646

Claim:
A power management Integrated Chip (IC), comprising: a startup circuit, powered by a power source, for supplying an operational power source within a startup period, wherein the startup circuit comprises: a controllable current source, coupled between the power source and the operational power source, having a control terminal; and a voltage detector, coupled to the control terminal and the operational power source, for turning off the controllable current source when voltage of the operational power source is higher than a predetermined value; a switch controller for controlling a power switch to increase or release energy in an energy conversion unit, wherein the switch controller comprises: a driving circuit for driving the power switch; and a Pulse Width Modulation (PWM) controller for controlling on time of the power switch; and a standby controller, powered by the power source, for receiving a standby signal, wherein when the standby signal is asserted, the standby controller fixes an output of the PWM controller, making the driving circuit turn off the power switch; wherein when the standby signal is asserted, the standby controller disables the startup circuit and the switch controller, making the startup circuit substantially supply no power to the operational power source and the switch controller turn off the power switch.