Abstract: The present invention relates to a power supply circuit that can intermittently operate when its load is small and therefore can reduce current consumption at a sleep mode. The power supply circuit for receiving an input voltage at an input terminal, converting the input voltage to an output voltage and outputting the output voltage to a load connected to an output terminal, comprises: a power supply circuit unit; an output current detecting circuit unit; and an output voltage detecting circuit unit; whereby the output supply voltage detecting circuit unit makes the power supply circuit unit operate when the detected voltage becomes equal to or lower than a predetermined value, and thereby the power supply circuit unit performs intermittent operations.

Abstract: A voltage regulator, which generates and outputs a given voltage based on a preset reference voltage, includes: a detection circuit part detecting the output voltage and generating and outputting a voltage based on the detected voltage; first and second operational amplifiers each comparing the output voltage of said detection circuit part and the preset reference voltage and outputting a voltage representing a comparison result, the first operational amplifier being controlled based on control signals supplied externally and consuming a larger amount of electric current than the second operational amplifier; and an output circuit part comprising an output transistor outputting an electric current based on the output voltages of the first and second operational amplifiers.

Abstract: A constant voltage circuit is disclosed that includes an output control transistor and an overcurrent protection circuit. The overcurrent protection circuit includes a proportional current generation circuit part, a current division circuit part, a division ratio control circuit part, a current-voltage conversion circuit part, and an output current control circuit part. When the output voltage of the current-voltage conversion circuit part reaches a predetermined voltage, the output current control circuit part prevents an increase in the output current of the output control transistor so as to reduce a voltage output from an output terminal. When the voltage output from the output terminal is reduced to a predetermined limit voltage, the division ratio control circuit part changes the division ratio of the current division circuit part so that a current supplied to the current-voltage conversion circuit part increases so as to reduce the output current of the output control transistor.

Abstract: A direct current power supply apparatus includes a first power supply circuit and a second power supply circuit. The first power supply circuit converts a source voltage from an externally supplied direct current power source into a first voltage and provides the first voltage to an output terminal. The second power supply circuit converts the source voltage from the externally supplied direct current power source into a second voltage and provides the second voltage to the output terminal. The second power supply circuit is controlled to be turned on and off. The first power supply circuit detects voltage at the output terminal and, when the second voltage is not being provided because the second power supply circuit is inactivated, provides the first voltage.

Abstract: An integrated circuit for supplying power includes an IC chip having a rectangular shape and having a first edge and a second edge opposite the first edge, a switching regulator implemented on the IC chip and having a driver transistor whose ON time of switching is controlled to adjust an output voltage of the switching regulator, and a series regulator implemented on the IC chip, wherein the driver transistor of the switching regulator is positioned near the first edge, and the series regulator is positioned near the second edge.

Abstract: A voltage regulator, which generates and outputs a given voltage based on a preset reference voltage, includes: a detection circuit part detecting the output voltage and generating and outputting a voltage based on the detected voltage; first and second operational amplifiers each comparing the output voltage of said detection circuit part and the preset reference voltage and outputting a voltage representing a comparison result, the first operational amplifier being controlled based on control signals supplied externally and consuming a larger amount of electric current than the second operational amplifier; and an output circuit part comprising an output transistor outputting an electric current based on the output voltages of the first and second operational amplifiers.