Patent ID: 8497650

Claim:
A fan delay control circuit, comprising: a fan connector electrically connected to a fan of an electronic device comprising a housing enclosure; a power supplying module electrically connected to the fan connector, wherein the power supplying module comprises a first terminal electrically connected to a fan power source, a second terminal electrically connected to a first stand-by power source, and a third terminal electrically connected to the fan connector, the power supplying module supplies power from the fan power source to the fan via the fan connector when the electronic device is powered on, and boosts the first stand-by power source and supplies the boosted power source to the fan via the fan connector when the electronic device is powered off; and a rotational controlling module comprising a first voltage buffer and a square wave generation circuit that is electrically connected to the fan connector via the first voltage buffer, wherein when the electronic device is powered off, the square wave generation circuit generates a square-wave signal to control rotational speed of the fan.