Abstract: A motor speed control circuit includes: a voltage generating circuit configured to change either a reference voltage corresponding to a target rotation speed of a motor or a speed voltage corresponding to a rotation speed of the motor, according to a temperature, and output the reference voltage and the speed voltage, either one of which is changed; a comparison circuit configured to compare the speed voltage output from the voltage generating circuit with the reference voltage output from the voltage generating circuit; and a driving circuit configured to drive the motor so as to match a level of the speed voltage to a level of the reference voltage, based on a comparison result from the comparison circuit.

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 speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a speed voltage circuit that generates a speed voltage corresponding to an actual rotational speed of the motor; a clamp circuit that limits the level of the speed voltage generated by the speed voltage circuit; a comparator that has the reference voltage generated by the reference voltage circuit and the speed voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control circuit includes: a voltage generating circuit configured to output a reference voltage corresponding to a target rotation speed of a motor and a speed voltage corresponding to a rotation speed of the motor, and change either the reference voltage or the speed voltage according to a temperature; a comparison circuit configured to compare the speed voltage with the reference voltage; and a driving circuit configured to drive the motor so as to match a level of the speed voltage to a level of the reference voltage, based on a comparison result from the comparison circuit.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a clamp circuit that limits a level of the reference voltage generated by the reference voltage circuit; a comparator that has a speed voltage corresponding to an actual rotational speed of the motor and the reference voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

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 speed control integrated circuit which controls a rotational speed of a motor by controlling the amount of current flowing through a drive coil of the motor. The integrated circuit comprises a first input terminal to have an analog speed-specifying signal in analog amount specifying the rotational speed of the motor input thereto; a second input terminal to have a digital speed-specifying signal in digital amount specifying the rotational speed of the motor input thereto; a reference voltage circuit that generates a reference voltage corresponding to the analog speed-specifying signal and/or the digital speed-specifying signal; a comparator that compares a speed voltage corresponding to the actual rotational speed of the motor and the reference voltage; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a clamp circuit that limits a level of the reference voltage generated by the reference voltage circuit; a comparator that has a speed voltage corresponding to an actual rotational speed of the motor and the reference voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a speed voltage circuit that generates a speed voltage corresponding to an actual rotational speed of the motor; a clamp circuit that limits the level of the speed voltage generated by the speed voltage circuit; a comparator that has the reference voltage generated by the reference voltage circuit and the speed voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control integrated circuit which controls a rotational speed of a motor by controlling the amount of current flowing through a drive coil of the motor. The integrated circuit comprises a first input terminal to have an analog speed-specifying signal in analog amount specifying the rotational speed of the motor input thereto; a second input terminal to have a digital speed-specifying signal in digital amount specifying the rotational speed of the motor input thereto; a reference voltage circuit that generates a reference voltage corresponding to the analog speed-specifying signal and/or the digital speed-specifying signal; a comparator that compares a speed voltage corresponding to the actual rotational speed of the motor and the reference voltage; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A semiconductor integrated circuit device with built-in spark killer diodes suitable for output transistor protection has a problem such that a leakage current to the substrate is great and a desirable forward current cannot be obtained. In a semiconductor integrated circuit device of the present invention, P+-type first and second diffusion regions 34 and 32 are formed on the surface of a second epitaxial layer 23 in a partly overlapping manner. And, by a connection to an anode electrode 39 at a part immediately over the P+-type second diffusion region 32, a parasitic resistance R1 is made greater than a parasitic resistance R2. Thus, an operation of a parasitic transistor TR2 that causes a leakage current to a substrate 21 is suppressed, whereby leakage current can be greatly reduced.

Abstract: A semiconductor integrated circuit device with built-in spark killer diodes suitable for output transistor protection has a problem such that a leakage current to the substrate is great and a desirable forward current cannot be obtained. In a semiconductor integrated circuit device of the present invention, P+-type first and second diffusion regions 34 and 32 are formed on the surface of a second epitaxial layer 23 in a partly overlapping manner. And, by a connection to an anode electrode 39 at a part immediately over the P+-type second diffusion region 32, a parasitic resistance R1 is made greater than a parasitic resistance R2. Thus, an operation of a parasitic transistor TR2 that causes a leakage current to a substrate 21 is suppressed, whereby leakage current can be greatly reduced.

Abstract: In order to brake a brushless motor in a forward rotation to give a reverse rotation force, source-side and sink-side transistors for supplying driving circuits *a, *b, *c, *d, *e, *f are periodically switched on and switched off based on the oscillation frequency of an oscillator (13) when a both end voltage of a current detection resistance (10) is higher than a reference voltage Vref. Moreover, the transistors are kept in an ON state all the time when the both end voltage of the current detection resistance (1) has lowered below the reference voltage Vref. With this arrangement, damage to a source-side transistor due to a large current flowing thereinto when the motor rotating in a reverse direction can be prevented.