Ricoh Company, Ltd.

Ricoh Electronic Devices Co., Ltd.

Yuuichi Ueda

A semiconductor integrated circuit includes a substrate of a first conductivity type, and a first MOS transistor and a second MOS transistor both formed in the substrate. The first MOS transistor includes first drain and first source regions as first active regions of a second conductivity type; a second active region of the first conductivity type; a first gate electrode disposed between the first drain and source regions; and a first substrate electrode connected to the second active region. The second MOS transistor includes a second drain region and a second source region which are formed between the first source region and the second active region, such that the first source region is proximate to the second drain region. The first substrate electrode is electrically separated from the first drain and source electrodes, and the second MOS transistor is connected between the first substrate electrode and the first source electrode.

Semiconductor integrated circuit and semiconductor integrated circuit apparatus

A current-restriction circuit includes an input terminal to which an input voltage is input, an output terminal from which an output voltage is output, a driver transistor connected to the input terminal as well as the output terminal, a sense transistor connected to the output terminal as well as the input terminal via a sense resistor, a first operational amplifier circuit, and a bias-voltage change circuit. Control terminals of the driver transistor and the sense transistor are connected together and connected to an output terminal of the first operational amplifier circuit. The first operational amplifier circuit receives both a bias voltage with reference to an electrical potential at the input terminal and a decrease in a voltage at the sense resistor. The bias-voltage change circuit keeps the bias voltage below a predetermined bias voltage according to a voltage difference between the input voltage and the output voltage.

Current-restriction circuit and driving method therefor

An excess-current protection circuit includes an outer input terminal, an outer output terminal, a driver transistor connected between the input terminal and the output terminal to control an excess current, an excess-current control circuit, and an excess-current detection circuit. The excess-current control circuit compares a predetermined first bias voltage with a voltage obtained by a current flowing through a first sense transistor multiplied by a resistance value of a sense resistor and controls the gate voltage of the driver transistor in accordance with a comparison result. The excess-current detection circuit compares voltage difference between the drain and source of the driver transistor with a predetermined second bias voltage and controls the gate voltage of the driver transistor in accordance with a comparison result.

Excess-current protection circuit and power supply

A charge pump provides high boosting efficiency with low power loss even with a heavy load. Plural charge transfer switches are connected in series forming two lines of charge transfer circuits operated by out-of-phase clock signals. Capacitors are connected to each of nodes in the charge transfer circuits. The charge transfer circuits include a first control unit, a second control unit, and a voltage comparison output unit. The second control unit includes a switch unit configured to selectively feed a signal from a previous-stage node or a later-stage node to the gate of a charge transfer switch in the second control unit, depending on the phase of the clock signal.

Voltage generating circuit

This patent specification describes a backflow prevention circuit which includes a first switch configured to conduct or to shut down a current path from an input terminal to an output terminal, a logic circuit configured to binarize an input voltage at the input terminal based on an output voltage at the output terminal and to output a binary signal and a shutdown circuit configured to cause the first switch to shut down independently of a switching control signal in accordance with the binary signal output from the logic circuit. The switching control signal performs a switching control of the first switch. The logic circuit outputs a shutdown signal to shut down independently of the switching control signal when the input voltage becomes smaller than the output voltage.

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Ikeda, Japan

Yuuichi Ueda