Abstract: A motor-drive circuit includes: an output transistor configured to supply a drive current to a motor for a cooling fan; a switching-control circuit configured to control switching of the output transistor so that the motor rotates in a first direction, or rotates in a second direction opposite to the first direction; and a switching circuit configured to, when a first time has elapsed since start of rotation of the motor in the first direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the first direction and thereafter rotates in the second direction, and configured to, when a second time has elapsed since start of rotation of the motor in the second direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the second direction and thereafter rotates in the first direction.

Abstract: A motor-drive circuit includes: an output transistor configured to supply a drive current to a motor for a cooling fan; a switching-control circuit configured to control switching of the output transistor so that the motor rotates in a first direction, or rotates in a second direction opposite to the first direction; and a switching circuit configured to, when a first time has elapsed since start of rotation of the motor in the first direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the first direction and thereafter rotates in the second direction, and configured to, when a second time has elapsed since start of rotation of the motor in the second direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the second direction and thereafter rotates in the first direction.

Abstract: A motor-drive circuit includes: an output transistor configured to supply a drive current to a motor for a cooling fan; a switching-control circuit configured to control switching of the output transistor so that the motor rotates in a first direction, or rotates in a second direction opposite to the first direction; and a switching circuit configured to, when a first time has elapsed since start of rotation of the motor in the first direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the first direction and thereafter rotates in the second direction, and configured to, when a second time has elapsed since start of rotation of the motor in the second direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the second direction and thereafter rotates in the first direction.

Abstract: A motor-drive circuit includes: an output transistor configured to supply a drive current to a motor for a cooling fan; a switching-control circuit configured to control switching of the output transistor so that the motor rotates in a first direction, or rotates in a second direction opposite to the first direction; and a switching circuit configured to, when a first time has elapsed since start of rotation of the motor in the first direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the first direction and thereafter rotates in the second direction, and configured to, when a second time has elapsed since start of rotation of the motor in the second direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the second direction and thereafter rotates in the first direction.

Abstract: The invention provides a motor with a low speed start function and a soft start function. The motor includes a first pulse generation circuit generating a first pulse signal of which a first duty ratio of one of logic levels is increased as a drive voltage corresponding the target rotation speed of the motor is increased, a second pulse generation circuit generating a second pulse signal of which a second duty ratio of one of logic levels is different from the first duty ratio, and a drive control circuit supplying a drive current to a motor coil at the second duty ratio in order to start the rotation of the motor that is stopping and supplying a drive current to the motor coil at the first duty ratio after a predetermined time passes from the start of the rotation of the motor in response to a rotation signal corresponding to the rotation of the motor.

Abstract: A motor-drive circuit includes: an output transistor configured to supply a drive current to a motor for a cooling fan; a switching-control circuit configured to control switching of the output transistor so that the motor rotates in a first direction, or rotates in a second direction opposite to the first direction; and a switching circuit configured to, when a first time has elapsed since start of rotation of the motor in the first direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the first direction and thereafter rotates in the second direction, and configured to, when a second time has elapsed since start of rotation of the motor in the second direction, cause the switching-control circuit to start switching control so that the motor stops rotating in the second direction and thereafter rotates in the first direction.

Abstract: A fan motor speed control circuit includes: a driving circuit configured to drive a fan motor so as to run at a rotation speed corresponding to a drive signal; a comparison circuit configured to output a comparison signal for matching a rotation speed of the fan motor with a target rotation speed, based on a reference signal corresponding to the target rotation speed of the fan motor and a speed signal corresponding to the rotation speed of the fan motor; and a selection circuit configured to output to the driving circuit the drive signal corresponding to one signal out of the reference signal and the comparison signal, the one signal being a signal by which the fan motor is driven at a higher rotation speed.

Abstract: A motor drive circuit includes: a pulse generation circuit configured to generate a pulse signal whose duty ratio of one logic level is increased as a drive voltage is increased in accordance with a target rotation speed of a motor; and a drive control circuit that configured to drive the motor with the drive voltage using a duty ratio higher than the duty ratio of the pulse signal when the motor starts rotating from the stopped state, and configured to drive the motor with the drive voltage during a period when the pulse signal is at the one logic level after the motor starts rotating, based on a rotation signal corresponding to the rotation of the motor.

Abstract: The invention provides a motor with a low speed start function and a soft start function. The motor includes a first pulse generation circuit generating a first pulse signal of which a first duty ratio of one of logic levels is increased as a drive voltage corresponding the target rotation speed of the motor is increased, a second pulse generation circuit generating a second pulse signal of which a second duty ratio of one of logic levels is different from the first duty ratio, and a drive control circuit supplying a drive current to a motor coil at the second duty ratio in order to start the rotation of the motor that is stopping and supplying a drive current to the motor coil at the first duty ratio after a predetermined time passes from the start of the rotation of the motor in response to a rotation signal corresponding to the rotation of the motor.

Abstract: A motor driving integrated circuit includes a data receiving circuit, a control circuit, and a pulse generating circuit. The data signal receiving circuit receives data signals inputted via a data signal input terminal. The control circuit controls the motor driving integrated circuit based on a first data signal received through the data signal receiving circuit. The pulse generating circuit generates a pulse signal for PWM (Pulse Width Modulation)—controlling a motor coil based on a second data signal received through the data signal receiving circuit. The pulse generating circuit includes a rectangular signal generating circuit configured to generate a plurality of rectangular signals different in pulse width, and a synthesizing circuit configured to synthesize the plurality of rectangular signals outputted from the rectangular signal generating circuit to generate the pulse signal with a duty ratio corresponding to the second data signal.

Abstract: According to some preferred embodiments of the present invention, a motor driving circuit includes a phase detection circuit configured to detect a rotation phase of a motor and output a phase detection signal, a first amplifier configured to amplify the phase detection signal and output an amplified detection signal, and a second amplifier configured to amplify the amplified detection signal in accordance with a power supply voltage and output a driving signal to the motor. The motor driving circuit is further provided with a controlling circuit configured to detect the power supply voltage and increase/decrease amplitude of the amplified detection signal outputted from the first amplifier in response to an increase/decrease of the detected power supply voltage, whereby heat generation and noise generation can be restrained, irrespective of the increase/decrease of the power supply voltage.

Abstract: A motor control circuit comprising: a rotation control circuit configured to control rotation of a motor based on a rotation control signal for controlling rotation of the motor and a rotational position detection signal from a Hall element for detecting a rotational position of the motor; a determining circuit configured to determine whether the rotation control signal has been generated for a predetermined time period; and a Hall element control circuit configured to apply a Hall element source voltage to the Hall element when the determining circuit determines that the rotation control signal has been generated for the predetermined time period, and to stop applying the Hall element source voltage to the Hall element when the determining circuit determines that the rotation control signal has not necessarily been generated for the predetermined time period.

Abstract: A motor drive circuit includes: a pulse generation circuit configured to generate a pulse signal whose duty ratio of one logic level is increased as a drive voltage is increased in accordance with a target rotation speed of a motor; and a drive control circuit that configured to drive the motor with the drive voltage using a duty ratio higher than the duty ratio of the pulse signal when the motor starts rotating from the stopped state, and configured to drive the motor with the drive voltage during a period when the pulse signal is at the one logic level after the motor starts rotating, based on a rotation signal corresponding to the rotation of the motor.

Abstract: A motor control circuit comprising: a rotation control circuit configured to control rotation of a motor based on a rotation control signal for controlling rotation of the motor and a rotational position detection signal from a Hall element for detecting a rotational position of the motor; a determining circuit configured to determine whether the rotation control signal has been generated for a predetermined time period; and a Hall element control circuit configured to apply a Hall element source voltage to the Hall element when the determining circuit determines that the rotation control signal has been generated for the predetermined time period, and to stop applying the Hall element source voltage to the Hall element when the determining circuit determines that the rotation control signal has not necessarily been generated for the predetermined time period.

Abstract: A fan motor speed control circuit includes: a driving circuit configured to drive a fan motor so as to run at a rotation speed corresponding to a drive signal; a comparison circuit configured to output a comparison signal for matching a rotation speed of the fan motor with a target rotation speed, based on a reference signal corresponding to the target rotation speed of the fan motor and a speed signal corresponding to the rotation speed of the fan motor; and a selection circuit configured to output to the driving circuit the drive signal corresponding to one signal out of the reference signal and the comparison signal, the one signal being a signal by which the fan motor is driven at a higher rotation speed.

Abstract: A motor driving integrated circuit for controlling motor driving, comprising: a data signal input terminal; a data signal receiving circuit configured to receive a data signal inputted from the data signal input terminal; a control circuit configured to control the motor driving integrated circuit based on a first data received through the data signal receiving circuit; and a pulse generating circuit configured to generate a pulse signal for PWM (Pulse Width Modulation)—controlling a motor coil based on a second data signal received through the data signal receiving circuit, the pulse generating circuit including: a rectangular signal generating circuit configured to generate a plurality of rectangular signals different in pulse width; and a synthesizing circuit configured to synthesize the plurality of rectangular signals outputted from the rectangular signal generating circuit to generate the pulse signal with a duty ratio corresponding to the second data signal.

Abstract: According to some preferred embodiments of the present invention, a motor driving circuit includes a phase detection circuit configured to detect a rotation phase of a motor and output a phase detection signal, a first amplifier configured to amplify the phase detection signal and output an amplified detection signal, and a second amplifier configured to amplify the amplified detection signal in accordance with a power supply voltage and output a driving signal to the motor. The motor driving circuit is further provided with a controlling circuit configured to detect the power supply voltage and increase/decrease amplitude of the amplified detection signal outputted from the first amplifier in response to an increase/decrease of the detected power supply voltage, whereby heat generation and noise generation can be restrained, irrespective of the increase/decrease of the power supply voltage.

Abstract: Two standard waves from a standard waveform generation circuit are output via an output gate while being interchanged by a direction selector. The switching operation of the direction selector is controlled by a direction control signal M/I. 200 cycles of the standard waveforms are counted up by a 200-cycle counter. A drive counter is downcounted every 200 cycles, while the drive counter is upcounted in accordance with the number of drive pulses DRIVE. When the count value of the drive counter becomes zero, output from the output gate is thereby stopped. At the time of startup, outputs from the 200-cycle counter are counted so as to output a drive wave in a predetermined number in a predetermined direction.

Abstract: Two standard waves from a standard waveform generation circuit are output via an output gate while being interchanged by a direction selector. The switching operation of the direction selector is controlled by a direction control signal M/I. 200 cycles of the standard waveforms are counted by a 200-cycle counter. A drive counter is downcounted every 200 cycles, while the drive counter is upcounted in accordance with the number of drive pulses DRIVE. When the count value of the drive counter becomes zero, output from the output gate is thereby stopped.

Abstract: A single-phase motor driving circuit includes a controller for outputting a control signal to drive a single-phase motor in a period in which a saw-tooth voltage of a predetermined cycle is larger than a duty setting voltage based on a result of comparing a detected temperature voltage changed based on a temperature detected by a temperature detecting device with a starting duty setting voltage increased with time while a voltage smaller than the detected temperature voltage at the time of starting the single-phase motor is set as an initial value. The controller sets the duty setting voltage as the starting duty setting voltage when the result of the comparison shows that the starting duty setting voltage is smaller than the detected temperature voltage, and the duty setting voltage as the detected temperature voltage when the starting duty setting voltage is larger than the detected temperature voltage.