Abstract: A three-phase brushless motor drive circuit switches its three-phase outputs by producing drive signals displaced in phase relative to one another. In this drive circuit, a reference clock is formed from the signals obtained by comparing the output voltages appearing across the coils of a three-phase motor individually with a voltage at a terminal common to the three phases. This reference clock is subjected to edge detection by an edge detection circuit. The output voltages include noises generated when the outputs are switched. The noise components produced when the reference clock is subjected to edge detection are reduced by a noise reduction circuit. A resulting edge detection output, which no longer includes noise components, is used to trigger an RS flip-flop to form a pulse-train signal. This pulse-train signal is used to control the charging and discharging of a capacitor.

Abstract: A peak level of a drive signal U having predetermined inclination portions is detected, and a detection signal Q is outputted when the peak level has not reached a predetermined value. Since the detection signal Q indicates the out-of-step condition of the motor, the use of the detection signal Q allows reactivation or the like to be triggered easily in a simple circuit. Therefore, the rotation of the motor can be activated by reactivation or the like without strict adjustment but with only a practically adequate adjustment.

Abstract: A motor control circuit includes a driver which amplifies a drive signal and outputs a drive current to a coil of a motor ; a detection circuit which detects a drive waveform of the drive current and outputs a detection pulse representing a rotating condition of the motor as a detection signal ; and a drive signal generating circuit which generates in response to the detection pulse a trapezoidal wave having a linear inclination at front and rear parts thereof as the drive signal.

Abstract: A motor control circuit which controls the speed of a motor so as to settle at a predetermined reference rotational speed based upon a detection signal dependent upon the rotating speed of the motor, and outputs to external devices a ready signal representing that the rotating speed of the motor has stabilized within a predetermined allowable range with respect to the reference rotational speed, includes a window pulse generating circuit which generates a window pulse having a width dependent upon a range of the generating period of the detection pulse generated in correspondence with the rotating speed within the allowable range; and a detection circuit which compares the window pulse and a detection pulse generated from the detection signal, detects either the window pulse or the detection pulse when the period of the detection pulse falls within a range of the period represented by the window of the window pulse and outputs the ready signal when the detection continues consecutively a plurality of times.

Abstract: A motor control circuit, which includes an input amplifying circuit which receives a detection signal relating to the rotation of a motor from a Hall element and amplifies the same, and a motor drive circuit which generates a drive current upon receipt of an output signal from the input amplifying circuit and drives the motor and in which at least the input amplifying circuit and the motor drive circuit are formed in an IC, a resistor disposed between the power source line and the Hall element outside the circuit formed in an IC and a diode disposed between the Hall element and a reference line in the forward direction, and wherein the diode is formed in an IC together with the input amplifying circuit and the motor drive circuit, and the diode voltage of the diode induced at the connection side with the Hall element is set nearly equal to or higher than the lower limit voltage level of the input signal of the input amplifying circuit.

Abstract: A motor control circuit, in which the motor is driven to rotate by a driving current according to a torque control signal and the motor rotation is stopped by generating a torque on the motor in the reversing direction when a stop signal for stopping the motor is received, further being provided with a level inverting circuit disposed between a torque control signal generating circuit and a drive circuit for inverting the level of the torque control signal with respect to a predetermined reference level, a level inverted torque control signal by the level inverting circuit is outputted to the drive circuit when the stop signal is received, and further provided with a reference signal generating circuit generating a reference signal corresponding to a reference rotational speed of the motor as well as generating another reference signal corresponding to a rotational speed lower than that of the reference rotational speed when the stop signal is received.