Abstract: The present disclosure provides a brushless motor driving circuit capable of clamping an output voltage at a proper voltage, even when a power source voltage changes. Namely, a pre-driver circuit generates a voltage for driving a brushless motor from a source voltage by turning on/off first and second PMOS transistors and first and second NMOS transistors in an H bridge circuit of a drive voltage generating circuit, and applies the voltage to a coil of the brushless motor. A first clamp circuit turns on/off the first NMOS transistor on the ground side so that the output voltage at a first output terminal becomes equal to or lower than the source voltage. A second clamp circuit turns on/off the second NMOS transistor on the ground side so that output voltage at a second output terminal becomes equal to or lower than the source voltage.

Abstract: An overcurrent detecting circuit includes a comparison transistor, a constant current source circuit, a subtraction circuit, and a comparison circuit. The comparison transistor is used for comparison with a main transistor provided in the power circuit. The constant current source circuit supplies a constant current to the comparison transistor. The subtraction circuit subtracts a voltage corresponding to a power supply voltage from a voltage between a drain and a source of the comparison transistor and outputs a voltage indicating the subtraction result. The comparison circuit compares the voltage output from the subtraction circuit with a voltage corresponding to a source voltage of the main transistor and outputs a voltage indicating the comparison result.

Abstract: A voltage generating circuit including first and second voltage sources, and a subtracting circuit. The subtraction circuit is configured as a differential amplifier including an op-amp and four resistors, with an inverting input terminal of the op-amp connected to the second voltage source via a first resistor, a second resistor connected between the inverting input terminal and an output terminal of the op-amp, a non-inverting input terminal of the op-amp connected to the first voltage source via a third resistor of the same size as the second resistor, the non-inverting input terminal of the op-amp connected to a reference potential terminal via a fourth resistor of the same size as the first resistor, the first voltage from the first voltage source and the second voltage from the second voltage source inputted to the subtracting circuit, and the subtracting circuit outputting a third voltage having a positive temperature coefficient.

Abstract: A brushless motor driving apparatus that includes a rotation signal output component, a half-cycle signal generating component, a plurality of counters, and a duty control signal generating component is provided. The plurality of counters, each of which uses a different bit number to count, repeatedly resets a count value and restarts a count operation for every bit number, resets a count value together with rising or falling of a half-cycle signal, and outputs a pulse signal which is inverted for every reset that occurs while the count operation is being performed. The duty control signal generating component generates a duty control signal to determine a duty ratio of a control signal to control driving of a single-phase brushless motor, based on at least two pulse signals selected from the pulse signals output from the plurality of counters.

Abstract: An overcurrent detecting circuit includes a comparison transistor, a constant current source circuit, and a comparison circuit. The comparison transistor includes a gate and a drain respectively connected to a gate and a drain of a main transistor provided in a power circuit. The comparison transistor is used for comparison with the main transistor when a voltage higher than a power supply voltage is applied to the gate of the main transistor and the gate of the comparison transistor during the operation of the power circuit. The constant current source circuit generates a constant current and supplies the constant current to the comparison transistor. The comparison circuit compares a source voltage of the comparison transistor with a source voltage of the main transistor and outputs a voltage indicating the comparison result.

Abstract: A motor driving apparatus that includes a current changing component, a detecting component, a control component, a back electromotive voltage zero cross detecting component, and a change control component. The current changing component drives a motor. The detecting component detects a point where a value of a magnitude of a current flowing into a coil of the motor changes from a decrease to an increase. The control component controls so that supply of the current to the coil is shut down, when the point is detected and the back electromotive voltage zero cross detecting component detects a zero cross of a back electromotive voltage generated in the coil. The change control component controls so that the direction of the current flowing into the coil changes to a reverse direction opposite to the predetermined direction, when the zero cross is detected.

Abstract: The present disclosure provides a brushless motor driving circuit capable of clamping an output voltage at a proper voltage, even when a power source voltage changes. Namely, a pre-driver circuit generates a voltage for driving a brushless motor from a source voltage by turning on/off first and second PMOS transistors and first and second NMOS transistors in an H bridge circuit of a drive voltage generating circuit, and applies the voltage to a coil of the brushless motor. A first clamp circuit turns on/off the first NMOS transistor on the ground side so that the output voltage at a first output terminal becomes equal to or lower than the source voltage. A second clamp circuit turns on/off the second NMOS transistor on the ground side so that output voltage at a second output terminal becomes equal to or lower than the source voltage.

Abstract: A driving circuit feeds driving current to a coil in a brushless motor, and feeds bias current to a Hall element that senses the rotational position of the motor. The driving current and bias current are supplied from the same power supply, but the bias current passes through a load element that reduces power dissipation by the Hall bias circuit by causing some of the power to be dissipated by the load element instead. The Hall bias circuit can therefore be combined with the other driving circuitry into a single integrated circuit, even if the brushless motor is driven at a comparatively high voltage.

Abstract: A motor speed regulating circuit includes a speed signal generator for generating a speed signal having a frequency proportional to the speed of the motor, synchronously with the rotation of the motor. A time difference detector is used for detecting a time difference between the period of the speed signal and a predetermined standard time. A control voltage generator is used for generating a speed control voltage to be applied to the motor in accordance with a detected time difference and feedback-controlling the speed of the motor in accordance with the standard time. A starter is used for starting the motor after the motor is stopped. The motor can be reliably restarted after it has been stopped.

Abstract: A semiconductor integrated circuit device incorporates a voltage step-up (boost) circuit which produces a stepped-up (boosted) voltage higher than the power voltage based on a periodic pulse signal generated internally or supplied from the outside. The stepped-up voltage is supplied to the emitter of a pnp driving transistor that produces a drive current for the output transistor on the voltage source side which is the one of a pair of npn output transistors in push-pull configuration. The voltage step-up circuit has its current supply capacity varied in response to the current flowing through the output transistor or driving transistor.

Abstract: A monolithic semiconductor integrated circuit device includes a differentially operative circuit section, an amplifying element connected to define a current flowing in the differentially operative circuit section and a circuit for adjusting a current flowing in the amplifying element to thereby compensate for variations of electric characteristics from one semiconductor device to another. The current adjusting circuit includes at least one amplifying element and a load resistance for the amplifying element in the current adjusting circuit. The load resistance has a structure suitable for a trimming operation to adjustably determine the resistance value of the load resistance.

Abstract: A variable electronic impedance circuit contains a voltage-current converter having an input terminal which is supplied with an input signal voltage, and a variable-gain current amplifier having an input terminal which is supplied with an output current of the voltage-current converter. The output signal current of the amplifier is fed back to the input terminal of the voltage-current converter.In order to prevent undesirable oscillation immediately after the closure of a power supply switch, the variable electronic impedance circuit includes a control circuit which substantially inhibits the operation of the voltage-current converter for a predetermined time after the closure of the power supply switch.

Abstract: An electronic impedance circuit is constructed of a voltage-current converter and a variable gain current amplifier. The voltage-current converter includes first and second transistors of the PNP-type differentially connected. The variable gain current amplifier includes third and fourth transistors of the NPN-type differentially connected, and fifth and sixth transistors of the PNP-type as load means. The bases of the third and fourth transistors are respectively driven by collector signals of the first and second transistors, and a collector signal of the third transistor is fed back to the base of the second transistor. In order to reduce a d.c. offset attributed to a current flowing between the base of the second transistor and the collector of the third transistor, a compensation circuit is connected to the variable gain amplifier.

Abstract: Either an input signal of a combining network or an output signal of an inverter arranged on a main path is fed to a side path through a mode switch in a switchable signal compressor/signal expander. Since an input terminal of a control amplifier is connected to a variable filter without passing through a signal amplifier, the deviation of the detection characteristic of a rectifier and integrator attributed to D.C. offset voltages of the signal amplifier and the control amplifier can be reduced. On the other hand, a switchable signal compressor/signal expander in another aspect of performance has a reference voltage generator for producing a D.C. reference voltage, and the output D.C. level of the control amplifier is maintained at a level approximate to the D.C. reference voltage. The other ends of first and second capacitors of the rectifier and integrator are also supplied with the D.C.