Patent ID: 7665319

Claim:
A fan control device, which receives a target revolution signal to control a rotation speed of a fan, comprising: a temperature measuring module measuring an ambient temperature of the fan to generate a temperature value; a revolution modulating module electrically connected with the temperature measuring module, receiving the temperature value and generating a control signal according to the temperature value and the target revolution signal; and a driving module electrically connected with the revolution modulating module and generating a driving signal according to the control signal to drive the fan, wherein the revolution modulating module comprises: a temperature modulating unit for receiving the temperature value and generating a temperature revolution signal according to the temperature value and the target revolution signal; a first constant speed modulating unit for generating a first speed limit signal according to the target revolution signal; an integrated control unit for generating the control signal according to at least one of the temperature revolution signal and the first speed limit signal; and a second constant speed modulating unit for generating a second speed limit signal according to the target revolution signal and a temperature speed limit signal, wherein the temperature speed limit signal is generated by the temperature modulating unit according to the temperature value.