Patent ID: 7646163

Claim:
A device for controlling rotation speed of a computer fan comprising: an identifying device configured for identifying the type of a computer fan, comprising a switch having a control terminal and a ground terminal, the control terminal connected to a power supply via a resistor, the ground terminal grounded; and a control circuit configured for controlling rotation speed of the computer fan comprising: an electric switch having a first terminal coupled to a node between the first resistor and the control terminal to receive an identifying signal generated by the identifying device, a second terminal coupled to a super input/output (I/O) chip to receive a pulse-width modulation (PWM) signal, and a third terminal; an integrated circuit having an input terminal connected to the third terminal of the electric switch, and an output terminal configured to output an analog voltage signal; a first output terminal connected to the super I/O chip, configured to output the PWM signal to a PWM control pin of a fan header; and a second output terminal configured to output the analog voltage signal to a power pin of the fan header.