CIRCUIT FOR WHICH POLYGONAL LINE-SHAPED CHARACTERISTIC CURVE OF FAN ROTATION SPEED IS DESIGNED

PROBLEM TO BE SOLVED: To provide a circuit by which the design of a fan rotation speed characteristic curve is facilitated. SOLUTION: This circuit comprises; a voltage dividing unit 10 which divides the voltage on receipt of electric power, outputs reference signals the level of which is changed based on the electric power level, and has a voltage division setting part 15 of the highest rotation speed, a voltage division setting part 16 of the lowest rotation speed, a voltage division setting part 14 of a high rotation speed characteristic curve conversion point, and a voltage division setting part 17 of a low rotation speed characteristic curve conversion point; a signal generation unit 20 which outputs control signals 21; a comparison unit 30 which is connected to the voltage dividing unit 10 and the signal generation unit 20, and by which pulse signals are generated based on the result of the comparison between the reference signals and the control signals 21; and a control unit 40 which is connected to the comparison unit 30, and by which the rotation speed of the connected fan motor is controlled based on the pulse signals output by the comparison unit. Based on four voltage division settings of the voltage dividing unit 10, a polygonal line-shaped characteristic curve of the fan rotation speed is designed. COPYRIGHT: (C)2009,JPO&INPIT