Fan system and control device thereof

A fan system comprising:

• a control device comprising a temperature sensing module, a comparing module and a driving module, wherein the temperature sensing module senses an external temperature so as to generate a sensing signal, the comparing module receives the sensing signal and outputs a comparing signal according to the sensing signal and a reference voltage signal, and the driving module is electrically connected with the temperature sensing module and the comparing module, supplies a working voltage to the temperature sensing module and the comparing module, and outputs a rotating speed control signal according to the sensing signal or the comparing signal when the fan system is in a normal state;
• and
• a motor receiving the rotating speed control signal and controlled to rotate according to the rotating speed control signals,
• wherein when the fan system is in an abnormal state, the rotating speed control signal makes the motor rotate at the full speed, wherein the abnormal state represents that a sensing member of the temperature sensing module is detached or broken.