Patent ID: 8248048

Claim:
A standby power supply circuit, comprising: a pulse width modulation (PWM) controller comprising a power terminal, a ground terminal, a compensation terminal, a feed back terminal, a booting terminal, a phase terminal, an upper gate terminal, and a lower gate terminal, wherein the power terminal of the PWM controller is connected to a first power source, the feed back terminal is connected to the compensation terminal via a first capacitor, the ground terminal is grounded, the booting terminal is connected to the phase terminal via a second capacitor; a first metal-oxide-semiconductor field effect transistor (MOSFET), wherein a drain of the first MOSFET is connected to the feed back terminal of the PWM controller, a gate of the first MOSFET is connected to a first general purpose terminal of a power management chip, a source of the first MOSFET is grounded via a first resistor; a second MOSFET, wherein a drain of the second MOSFET is connected to the drain of the first MOSFET, a gate of the second MOSFET is connected to a second general purpose terminal of the power management chip, a source of the second MOSFET is grounded via a second resistor; a third MOSFET, wherein a drain of the third MOSFET is connected to a second power source, a gate of the third MOSFET is connected to the upper gate terminal of the PWM controller, a source of the third MOSFET is connected to the phase terminal of the PWM controller; a fourth MOSFET, wherein a drain of the fourth MOSFET is connected to the source of the third MOSFET, a gate of the fourth MOSFET is connected to the lower gate terminal of the PWM controller, a source of the fourth MOSFET is grounded; an inductor, wherein the phase terminal of the PWM controller is connected to a first terminal of a third capacitor via the inductor, a second terminal of the third capacitor is grounded, the drain of the second MOSFET is connected to a node between the inductor and the third capacitor via a third resistor, the node between the inductor and the third capacitor outputs a standby power.