Patent ID: 8174227
Filing Date: 2012-05-08
Classification: F04D,Y02B

Abstract:
1. A fan control system for controlling a rotation rate of a fan, comprising: a temperature detecting circuit comprising a first amplifier, a second amplifier, and a thermistor, wherein power terminals of the first amplifier and the second amplifier are connected to a first power supply, ground terminals of the first amplifier and the second amplifier are grounded, a non-inverting input of the first amplifier is connected to a second power supply via a first resistor, an inverting input of the first amplifier is grounded via a second resistor, an output of the first amplifier is connected to the non-inverting input of the first amplifier via a third resistor, the output of the first amplifier is also connected to a non-inverting input of the second amplifier via the thermistor, an inverting input of the second amplifier is grounded, an output of the second amplifier is connected to the non-inverting input of the second amplifier via a fourth resistor, the output of the second amplifier outputs a voltage signal; and a rotation rate control circuit comprising a first terminal connected to the first power supply, a second terminal connected to the output of the second amplifier to receive the voltage signal, and a third terminal connected to the fan, to control the rotation rate of the fan according to the voltage signal.