Nippon Electric Co., Ltd.

Nec Corporation

Jun Kishi

Hirokazu Fukaya

Hirokazu Kukaya

A motor driving circuit capable of controlling a motor speed by a current controlled method using negative impedance is constituted by a constant-current circuit, a reference voltage generating circuit, a comparator circuit, an output driving circuit, a symmetric current circuit, and a switching circuit. The reference voltage generating circuit outputs a voltage of a value derived from addition of a reference voltage and a voltage proportional to a value of a current flowing to a motor. The comparator circuit compares a voltage outputted from the reference voltage generating circuit and a voltage at an output terminal. The output driving circuit amplifies an output of the comparator circuit. The symmetric current circuit amplifies the output from the output driving circuit. The switching circuit performs switching of connections of one of transistors in the symmetric current circuit between the input of the reference voltage generating circuit and the output terminal, and can release the motor from a normal state of operation upon starting the motor. Thus, it is possible to achieve sufficient torque during the starting operation of the motor.

Driving circuit for direct-current (DC) motor

A semiconductor device comprising at least two pinch resistors or two ion-implanted resistors having a precise resistance ratio therebetween. The pinch resistor and ion-implanted resistor have at least one region contributing to the determination of a resistance value, respectively. In two pinch resistors or two ion-implanted resistors, a ratio in number of a plurality of regions in one resistor to at least one region in the other resistor is selected to be identical to the resistance ratio of one resistor to the other resistor, resulting in that a precise resistance ratio is realized despite different configurations of the two resistors.

Semiconductor device having at least two resistors with high resistance

Motor rotation speed control circuit

A motor speed control circuit includes a resistor, a voltage reference circuit, a first voltage comparator, a current mirror circuit for deriving first and second output currents according to the output of the first voltage comparator, and a motor. A voltage consisting of the sum of a reference voltage and a voltage generated across the resistor by the first output current of the current mirror circuit is applied to the first input terminal of the first voltage comparator. The second output current of the current mirror circuit is fed to the motor and to the second input terminal of the first voltage comparator. A second comparator detects the voltage difference between the first and second input terminals of the first voltage comparator. The output of the second comparator is applied to the current mirror circuit to enhance the starting torque of the motor.

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Tokyo, Japan

Jun Kishi