Patent ID: 8049450
Filing Date: 2011-11-01
Classification: H05K

Abstract:
1. A fan control circuit for controlling a fan to dissipate heat from an electrical device, comprising: a comparator comprising an input terminal connected to a power source via a first resistor, and connected to an input of the electrical device for receiving a working current draw of the electrical device, a reference terminal for receiving a reference voltage, and an output terminal for outputting a comparison result according to a voltage received by the input terminal and the reference voltage, wherein the voltage at the input terminal is inversely proportional to the working current draw of the electrical device multiplied by the resistance of the first resistor; and an electrical switch comprising a control terminal connected to the output terminal of the comparator for receiving the comparison result, a first terminal connected the power source via a second resistor, and a second terminal grounded, the fan being connected to the first terminal; wherein the fan is turned on or turned off according to the working current draw of the electrical device.