Power source generation circuit and integrated circuit

An integrated circuit comprising:

• a regulator circuit which receives a pulsed external power source voltage from an external circuit, generates a predetermined internal power source voltage on a given terminal, and includes a first switching transistor, one of a source and a drain of the first switching transistor being connected to the external circuit;
• and
• a charging circuit which is connected to the external circuit and, connects the external circuit and the given terminal when an external power source voltage received from the external circuit is equal to or lower than a predetermined threshold voltage,
• wherein the charging circuit is configured to output the pulsed external power voltage to the given terminal before the regulator circuit generates the predetermined internal power source voltage on the given terminal.

An integrated circuit comprising:

• a regulator circuit which receives an external power source voltage from an external power source and provides a predetermined power source voltage generated internally, and includes a first switching transistor, a source of the first switching transistor being connected to the external power source;
• and
• a charging circuit which includes a second switching transistor having a source connected to the external power source and a drain connected to a first terminal, wherein:
• the second switching transistor turns ON to provide the external power source voltage received from the external power source to the first terminal via the second switching transistor when the external power source voltage is below a predetermined threshold voltage,
• the first switching transistor is a first p-type Metal Oxide Semiconductor (MOS) transistor,
• the second switching transistor is a second p-type MOS transistor having a gate that is controlled based on the external power source voltage and a variable input signal,
• a source-drain path of the first p-type MOS transistor and a source-drain path of the second p-type MOS transistor are not connected in series, and
• the charging circuit is configured to supply the external power source voltage to the first terminal before the regulator circuit generates the predetermined power source voltage on the first terminal.

An integrated circuit comprising:

• a regulator circuit which receives an external power source voltage from an external power source and provides a predetermined power source voltage generated internally, and includes a first switching transistor, one of a source and a drain of the first switching transistor being connected to the external power source;
• and
• a charging circuit which includes a second switching transistor with one of a source and a drain connected to the external power source and another of the source and the drain connected to a first terminal, wherein:
• the second switching transistor turns ON to provide the external power source voltage received from the external power source to the first terminal via the second switching transistor when the external power source voltage is below a predetermined threshold voltage,
• the first switching transistor is a first Metal Oxide Semiconductor (MOS) transistor,
• the second switching transistor is a second MOS transistor having a gate controlled based on the external power source voltage and a variable input signal applied to a second terminal,
• the second terminal is not on a path between the gate of the second MOS transistor and the external power source, and
• the charging circuit is configured to supply the external power source voltage to the first terminal before the regulator circuit generates the predetermined power source voltage on the first terminal.

An integrated circuit comprising:

• a first circuit which receives an external power source voltage from an external power source and provides a predetermined power source voltage generated internally, and includes a first Metal Oxide Semiconductor (MOS) transistor, one of a source and a drain of the first MOS transistor being connected to the external power source;
• and
• a second circuit which includes a second MOS transistor with one of a source and a drain connected to the external power source and another of the source and the drain connected to a first terminal, wherein:
• the second MOS transistor turns ON to provide the external power source voltage received from the external power source to the first terminal via the second MOS transistor when the external power source voltage is below a predetermined threshold voltage,
• a gate signal applied to a gate of the second MOS transistor is controlled based on the external power source voltage and a variable signal,
• the gate signal is not supplied to the first circuit, and
• the charging circuit is configured to supply the external power source voltage to the first terminal before the regulator circuit generates the predetermined power source voltage on the first terminal.