Importance

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Abstract

A motor controller controlling a rotational speed of a motor and including a thermal detector, a capacitor, an operational amplifier (OP), a charging/discharging circuit, a flip-flop and a logic circuit. The thermal detector detects environmental temperature of the motor to set a first reference voltage. The capacitor has one terminal coupled to a second reference voltage while another terminal thereof is charged/discharged by the charging/discharging circuit, controlled by a pulse width modulation (PWM) signal, to provide a third reference voltage. The OP compares the first and third reference voltages and outputs the comparison result to a ‘set’ terminal of the flip-flop. The flip-flop further uses a ‘reset’ terminal to receive a clock signal and the output signal thereof is utilized in generating the PWM signal. The PWM signal is further provided to the logic circuit for setting a duty cycle of a driving current of the motor.

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First Claim