Abstract: The light receiving circuit includes: a photoelectric conversion element for causing a current corresponding to an amount of incident light to flow; a MOS transistor including a source connected to the photoelectric conversion element and a drain connected to a node, for causing the current of the photoelectric conversion element to flow to the node while maintaining a voltage of the source to a first voltage; a reset circuit for causing a current to flow from the node to a GND terminal so that a voltage of the node becomes a second voltage lower than the first voltage; a control circuit for outputting a reset signal to the reset circuit; and a voltage increase detection circuit for detecting a fluctuation in the voltage of the node and outputting a detection result.

Abstract: Provided is a voltage regulator capable of controlling an output voltage to a predetermined voltage quickly after an overshoot occurs in the output voltage. The voltage regulator includes: an overshoot detection circuit configured to detect a voltage that is based on an output voltage of the voltage regulator, and output a current corresponding to an overshoot amount of the output voltage; and an I-V converter circuit configured to control a current flowing through an output transistor based on a current controlled by an output of an error amplifier and a current flowing from the overshoot detection circuit.

Abstract: Provided is a voltage regulator capable of controlling an output voltage to a predetermined voltage quickly after an undershoot occurs in the output voltage. The voltage regulator includes: an undershoot detection circuit configured to detect a voltage that is based on an output voltage of the voltage regulator, and output a current corresponding to an undershoot amount of the output voltage; and an I-V converter circuit configured to control a current flowing through an output transistor based on a current controlled by an output of an error amplifier and a current flowing from the undershoot detection circuit.

Abstract: Provided is a voltage regulator capable of, when an overshoot or undershoot occurs in an output voltage, improving the overshoot or undershoot in a wide temperature range and reducing a delay in detection of the overshoot or undershoot. The voltage regulator includes: an error amplifier; an output transistor; and a first transistor including a gate for inputting a reference voltage and a source for inputting an output voltage. The first transistor is configured to cause a current to flow when the output voltage becomes an irregular voltage, and a current of the output transistor is controlled based on the current flowing through the first transistor.

Abstract: The voltage reference circuit includes: a first MOS transistor; a second MOS transistor including a gate terminal connected to a gate terminal of the first MOS transistor and having an absolute value of a threshold value and a K value higher than an absolute value of a threshold value and a K value of the first MOS transistor; a current mirror circuit flowing a current based on a difference between the absolute values of the threshold values of the first MOS transistor and the second MOS transistor; a third MOS transistor flowing the current; and a fourth MOS transistor having an absolute value of a threshold value and a K value higher than an absolute value of a threshold value of the third MOS transistor and flowing the current.

Abstract: Provided is a proximity sensor using a photosensor, which is easy to use and reduced in power consumption. In the proximity sensor, a first photosensor is used to detect a change in amount of ambient light entering the first photosensor, which is caused when a finger is coming close thereto, and a detection signal is output based on a result of the detection. The photosensor includes, for example, one or a plurality of PN junction elements connected in parallel.

Abstract: Provided is a semiconductor integrated circuit including a variable resistor circuit of the small layout area, which is free from an error in resistance caused by ON-state resistances of switch elements for trimming, and is also free from power supply voltage dependence and temperature dependence. The semiconductor integrated circuit including a variable resistor circuit includes: a resistor circuit including a plurality of series-connected resistors; a selection circuit including a plurality of switch elements for selecting a connected number of the plurality of series-connected resistors; and a control circuit for controlling ON-state resistances of the plurality of switch elements. The control circuit controls the ON-state resistances of the plurality of switch elements so as to obtain a predetermined ratio to a resistance of the plurality of series-connected resistors of the resistor circuit.

Abstract: Provided is an electronic device capable of supplying desired electric power to a load so as to operate the load even in a case where charged power is minute and a voltage increase rate of a capacitor, which increases by charge, is low. The electronic device includes: a power source which has supply power less than consumption power of the load; a capacitor to be charged with the supply power; and a charge/discharge control circuit which controls charging of the capacitor and consumption of charged power of the capacitor by the load, and the charge/discharge control circuit includes: a first node to which the supply power of the power source is supplied; and a circuit which charges the capacitor with the supply power from the first node.

Abstract: The device identification apparatus includes: a remote controller signal detecting section for detecting an optical signal from a remote controller; a receiving section for receiving the optical signal from the remote controller; a signal decryption section for decrypting the optical signal received by the receiving section; and a transmitting section for transmitting a device identification signal when the optical signal is a device selecting signal, and configured such that operations of the receiving section, the signal decryption section, and the transmitting section are started in response to a detecting signal of the remote controller signal detecting section, thereby realizing a device identification apparatus in which power consumption during standby is minimized.

Abstract: Each device identification apparatus includes a circuit for generating a delay time and transmits a device identification code signal at a different delay time in response to a device selecting signal from a remote controller, thereby making it possible to prevent interference. Further, an infrared light amount detecting circuit is provided in a device identification apparatus or a remote controller, and an electronic device to which a device identification apparatus having a higher intensity of infrared is attached is displayed on the remote controller so that the electronic device is easily selected.

Abstract: A constant current flowing through a first depletion transistor whose gate and source are connected to each other is caused to flow through a second depletion transistor having the same threshold as the first depletion transistor, to thereby generate a first voltage between a gate and a source of the second depletion transistor. The constant current of the first depletion transistor and a constant current flowing through a third depletion transistor whose gate and source are connected to each other are caused to flow through a fourth depletion transistor. A threshold of the fourth depletion transistor is the same as that of the third depletion transistor but different from that of the first depletion transistor, and hence a second voltage is generated between a gate and a source of the fourth depletion transistor. A reference voltage is generated based on a voltage difference between the first and second voltages.

Abstract: Provided is a light receiving circuit for detecting a change in amount of light, in which an input circuit at a subsequent stage is compact and inexpensive and current consumption is low. The light receiving circuit includes: a photoelectric conversion element for supplying a current corresponding to an amount of incident light; an N-channel MOS transistor including a drain supplied with the current from the photoelectric conversion element; and a control circuit for controlling a gate voltage of the NMOS transistor via a low pass filter so that a drain voltage of the N-channel MOS transistor becomes a desired voltage.

Abstract: The voltage reference circuit includes: a first MOS transistor; a second MOS transistor including a gate terminal connected to a gate terminal of the first MOS transistor and having an absolute value of a threshold value and a K value higher than an absolute value of a threshold value and a K value of the first MOS transistor; a current mirror circuit flowing a current based on a difference between the absolute values of the threshold values of the first MOS transistor and the second MOS transistor; a third MOS transistor flowing the current; and a fourth MOS transistor having an absolute value of a threshold value and a K value higher than an absolute value of a threshold value of the third MOS transistor and flowing the current.

Abstract: Provided is a magnetic sensor circuit capable of a low-voltage operation, which comprises a Hall element and a magnetic offset cancellation circuit for the Hall element. In the magnetic sensor circuit using the Hall element, at the time of turning on transmission gates for switching connections between input terminals of an amplifier circuit in the magnetic offset cancellation circuit and electrodes of the Hall element in order to cancel a magnetic offset of the Hall element, gates of N-channel transistors in the transmission gates are set at voltages higher than a power supply voltage by a drive circuit.

Abstract: Provided is a convenient mouse device having low power consumption. The mouse device has a configuration in which an optical sensor for light shielding detection is provided in a region where a hand blocks light when the hand handles the mouse device so that the mouse device may perform a normal operation when the optical sensor for light shielding detection is shielded from light, and may perform a low consumption operation when the optical sensor for light shielding detection is not shielded from light.

Abstract: Provided is a photodetector circuit having significantly low current consumption. The photodetector circuit includes two opposing P-channel metal oxide semiconductor (MOS) transistors each including a gate connected to a drain of the opposing P-channel MOS transistor. The drain of one of the P-channel MOS transistors is discharged with an ON-state current of an N-channel MOS transistor which is turned ON with a voltage generated in a photoelectric element. The drain of the other of the P-channel MOS transistors is discharged with an ON-state current of a depletion type N-channel MOS transistor including a gate to which a voltage of a reference power supply terminal is input, and a source to which the voltage generated in the photoelectric element is input.

Abstract: Provided is a reference voltage circuit with improved temperature characteristics. A current based on a current flowing through a first depletion transistor whose gate and source are connected to each other is caused to flow through a third depletion transistor having the same threshold, to thereby generate a voltage between a gate and a source of the third depletion transistor. A current based on a current flowing through a second depletion transistor whose gate and source are connected to each other is caused to flow through a fourth depletion transistor having the same threshold, to thereby generate a voltage between a gate and a source of the fourth depletion transistor. A reference voltage is generated based on a difference voltage of the two voltages, to thereby obtain a reference voltage having less voltage fluctuations with respect to a temperature change.

Abstract: Provided is a semiconductor integrated circuit including a variable resistor circuit of the small layout area, which is free from an error in resistance caused by ON-state resistances of switch elements for trimming, and is also free from power supply voltage dependence and temperature dependence. The semiconductor integrated circuit including a variable resistor circuit includes: a resistor circuit including a plurality of series-connected resistors; a selection circuit including a plurality of switch elements for selecting a connected number of the plurality of series-connected resistors; and a control circuit for controlling ON-state resistances of the plurality of switch elements. The control circuit controls the ON-state resistances of the plurality of switch elements so as to obtain a predetermined ratio to a resistance of the plurality of series-connected resistors of the resistor circuit.

Abstract: Provided is a light receiving circuit for detecting a change in amount of light, in which an input circuit at a subsequent stage is compact and inexpensive and current consumption is low. The light receiving circuit includes: a photoelectric conversion element for supplying a current corresponding to an amount of incident light; an N-channel MOS transistor including a drain supplied with the current from the photoelectric conversion element; and a control circuit for controlling a gate voltage of the NMOS transistor via a low pass filter so that a drain voltage of the N-channel MOS transistor becomes a desired voltage.

Abstract: Provided is a proximity sensor using a photosensor, which is easy to use and reduced in power consumption. In the proximity sensor, a first photosensor is used to detect a change in amount of ambient light entering the first photosensor, which is caused when a finger is coming close thereto, and a detection signal is output based on a result of the detection. The photosensor includes, for example, one or a plurality of PN junction elements connected in parallel.