Ricoh Company, Ltd.

Sharp Kabushiki Kaisha Corporation

Analog Research Limited

Yusuke Minakuchi

Yoshiki Takagi

Kohji Yoshii

Toshihisa Nagata

A constant voltage circuit that is capable of realizing high speed response with respect to an abrupt change in an input voltage or a load current is disclosed. The constant voltage circuit includes a first error amplifier with a high direct current gain and a second error amplifier with high speed responsiveness with respect to a change in an output voltage. The constant voltage circuit uses the first and second error amplifiers to conduct operation control of an output voltage control transistor in response to a change in the output voltage.

Constant voltage circuit using plural error amplifiers to improve response speed

A constant voltage circuit which is capable of quickly responding to a sudden change of an output voltage includes an output transistor, and first and second error amplifiers. The output transistor outputs a power with an output voltage and an output current to a load. The first error amplifier is configured to increase a response speed with respect to changes of the output voltage in accordance with an increase of the output current so as to control operations of the output transistor. The second error amplifier has a response speed faster than the first error amplifier with respect to changes of the output voltage, and is configured to decrease a gain thereof in response to a drain current of the output transistor.

Constant voltage circuit capable of quickly responding to a sudden change of load current

A constant-voltage circuit in which a response speed for a sudden change of an input voltage or a sudden change of a load current can be fast are disclosed. In normal operating conditions, a first control circuit (error amplifier circuit) having an excellent direct-current characteristic controls operations of an output voltage control transistor and an output voltage is made a constant voltage. When the output voltage is suddenly decreased, before the first control circuit controls the operations of the output voltage control transistor by responding to the sudden decrease of the output voltage, an amplifier circuit having a high-speed response characteristic amplifies the change of the output voltage, and when the amplified voltage obtained by the amplification is suddenly decreased, a second control circuit controls the operations of the output voltage control transistor for a predetermined period. With this, the output voltage can be a constant voltage.

Constant-voltage circuit and controlling method thereof

Voltage regulator with plural error amplifiers

A constant power voltage circuit includes a first transistor for generating a collector current, a second transistor for generating a collector current, a third transistor, the collector of which is connected to the collector of the first transistor, a fourth transistor, the collector of which is connected to the collector of the second transistor, an emitter-grounded amplifier circuit including a fifth transistor for providing a feedback loop, with a fifth transistor, the collector which is connected to a constant current circuit and the base current of the third and the fourth transistors, being outputted from the constant current circuit upon the application of a power source.

Growing community of inventors

Nara, Japan

Yusuke Minakuchi