Heat dissipation system, rotation speed control circuit and method thereof

A rotation speed control circuit, comprising:

• a temperature-controlled voltage duty generator, converting a temperature-controlled voltage into a digital temperature-controlled voltage and executing a linear interpolation operation according to a first setting data so as to output a temperature-controlled voltage duty signal, wherein the temperature-controlled voltage varies with a temperature change;
• a pulse-width signal duty generator, converting a pulse-width input signal received to a digital pulse-width input signal and executing the linear interpolation operation according to a second setting data so as to output a pulse-width duty signal;
• a multiplier, connected to the temperature-controlled voltage duty generator and the pulse-width signal duty generator, and the multiplier executing a multiplication on the temperature-controlled voltage duty signal and the pulse-width duty signal received so as to outputs mixing-duty signal;
• and
• a rotation speed signal generator, connected to the multiplier, and the rotation speed signal generator receiving the mixing-duty signal and a third setting data, and accordingly executes a minimum output duty operation so as to outputs a pulse-width output signal.