Abstract: To satisfy the NFC communication standard in wireless charging with a shared antenna, used for NFC communication. A power supply unit includes a voltage step-down circuit 331, a charge control circuit 332, and a communication controller power supply circuit 333. The voltage step-down circuit includes a switching regulator 200, and a selection circuit 206 and 208 which can select an output path PT1 of the switching regulator and a bypass path PT2 of the switching regulator. The voltage step-down circuit includes a selection control circuit 207. The selection control circuit supplies voltage to the communication controller power supply circuit via the bypass path at the time of activating the communication controller. Since the output voltage of the series regulator stabilizes in a shorter time than the switching regulator, it becomes possible to keep the time from when RF power rises to when initial communication becomes possible, within standards.

Abstract: A semiconductor integrated circuit and its operating method are provided. The present circuit has first and second supply terminals capable of supplying first and second power supply voltages respectively, an input voltage selection circuit coupled to the first and second supply terminals, and first and second power supply switches. The input voltage selection circuit includes a power-on reset circuit, an input voltage detection circuit and a control circuit. When the supply of the first or second power supply voltage to one of both supply terminals is detected upon completion of a power on reset operation, one of both power supply switches and the other thereof are controlled to on and off respectively. When the supply of both power supply voltages to both supply terminals is detected, the one thereof and the other thereof are respectively controlled to on and off according to the preset order of precedence.

Abstract: Disclosed are a semiconductor integrated circuit including first and second supply terminals; an input voltage selection circuit including a power-on reset circuit, an input voltage detection circuit, a control circuit and a power-on reset auxiliary circuit; and first and second power supply switches, and its operating method. When the above detection circuit detects the supply of both first and second power supply voltages to both supply terminals upon completion of a power on reset operation of the reset circuit, the control circuit controls either of both power supply switches, having a high priority of preset priorities, to an on state. After its control, the auxiliary circuit detects a power failure in the power supply voltage supplied to the high-priority power supply switch. The reset circuit performs another power on reset operation. The control circuit controls the power supply switch having a low priority of the priorities to an on state.

Abstract: The present invention is to reduce the possibility that a DC-DC converter stops in the case where supply power is small and load current is large. Output terminals use a DC output voltage of a DC-DC converter so that an external battery can be charged or power can be supplied to a power-reception-side system on the outside, and a current limiting circuit limits load current of a power supply switch transistor flowing from a converter output terminal to the output terminals. An input voltage detecting circuit detects level of a DC input voltage of an input terminal, generates a detection signal, and supplies the detection signal to the current limiting circuit. In the case where the DC input voltage of the input terminal is at the low level, the current limiting circuit controls the maximum current by current limitation of the power supply switch transistor to a small current.

Abstract: A semiconductor integrated circuit and its operating method are provided. The present circuit has first and second supply terminals capable of supplying first and second power supply voltages respectively, an input voltage selection circuit coupled to the first and second supply terminals, and first and second power supply switches. The input voltage selection circuit includes a power-on reset circuit, an input voltage detection circuit and a control circuit. When the supply of the first or second power supply voltage to one of both supply terminals is detected upon completion of a power on reset operation, one of both power supply switches and the other thereof are controlled to on and off respectively. When the supply of both power supply voltages to both supply terminals is detected, the one thereof and the other thereof are respectively controlled to on and off according to the preset order of precedence.

Abstract: To satisfy the NFC communication standard in wireless charging with a shared antenna, used for NFC communication. A power supply unit includes a voltage step-down circuit 331, a charge control circuit 332, and a communication controller power supply circuit 333. The voltage step-down circuit includes a switching regulator 200, and a selection circuit 206 and 208 which can select an output path PT1 of the switching regulator and a bypass path PT2 of the switching regulator. The voltage step-down circuit includes a selection control circuit 207. The selection control circuit supplies voltage to the communication controller power supply circuit via the bypass path at the time of activating the communication controller. Since the output voltage of the series regulator stabilizes in a shorter time than the switching regulator, it becomes possible to keep the time from when RF power rises to when initial communication becomes possible, within standards.

Abstract: To satisfy the NFC communication standard in wireless charging with a shared antenna, used for NFC communication. A power supply unit includes a voltage step-down circuit 331, a charge control circuit 332, and a communication controller power supply circuit 333. The voltage step-down circuit includes a switching regulator 200, and a selection circuit 206 and 208 which can select an output path PT1 of the switching regulator and a bypass path PT2 of the switching regulator. The voltage step-down circuit includes a selection control circuit 207. The selection control circuit supplies voltage to the communication controller power supply circuit via the bypass path at the time of activating the communication controller. Since the output voltage of the series regulator stabilizes in a shorter time than the switching regulator, it becomes possible to keep the time from when RF power rises to when initial communication becomes possible, within standards.

Abstract: The present invention is to reduce the possibility that a DC-DC converter stops in the case where supply power is small and load current is large. Output terminals use a DC output voltage of a DC-DC converter so that an external battery can be charged or power can be supplied to a power-reception-side system on the outside, and a current limiting circuit limits load current of a power supply switch transistor flowing from a converter output terminal to the output terminals. An input voltage detecting circuit detects level of a DC input voltage of an input terminal, generates a detection signal, and supplies the detection signal to the current limiting circuit. In the case where the DC input voltage of the input terminal is at the low level, the current limiting circuit controls the maximum current by current limitation of the power supply switch transistor to a small current.

Abstract: Disclosed are a semiconductor integrated circuit including first and second supply terminals; an input voltage selection circuit including a power-on reset circuit, an input voltage detection circuit, a control circuit and a power-on reset auxiliary circuit; and first and second power supply switches, and its operating method. When the above detection circuit detects the supply of both first and second power supply voltages to both supply terminals upon completion of a power on reset operation of the reset circuit, the control circuit controls either of both power supply switches, having a high priority of preset priorities, to an on state. After its control, the auxiliary circuit detects a power failure in the power supply voltage supplied to the high-priority power supply switch. The reset circuit performs another power on reset operation. The control circuit controls the power supply switch having a low priority of the priorities to an on state.

Abstract: A semiconductor integrated circuit and its operating method are provided. The present circuit has first and second supply terminals capable of supplying first and second power supply voltages respectively, an input voltage selection circuit coupled to the first and second supply terminals, and first and second power supply switches. The input voltage selection circuit includes a power-on reset circuit, an input voltage detection circuit and a control circuit. When the supply of the first or second power supply voltage to one of both supply terminals is detected upon completion of a power on reset operation, one of both power supply switches and the other thereof are controlled to on and off respectively. When the supply of both power supply voltages to both supply terminals is detected, the one thereof and the other thereof are respectively controlled to on and off according to the preset order of precedence.

Abstract: To satisfy the NFC communication standard in wireless charging with a shared antenna, used for NEC communication. A power supply unit includes a voltage step-down circuit 331, a charge control circuit 332, and a communication controller power supply circuit 333. The voltage step-down circuit includes a switching regulator 200, and a selection circuit 206 and 208 which can select an output path PT1 of the switching regulator and a bypass path PT2 of the switching regulator. The voltage step-down circuit includes a selection control circuit 207. The selection control circuit supplies voltage to the communication controller power supply circuit via the bypass path at the time of activating the communication controller. Since the output voltage of the series regulator stabilizes in a shorter time than the switching regulator, it becomes possible to keep the time from when RF power rises to when initial communication becomes possible, within standards.

Abstract: An operational amplifier includes a differential amplifier circuit provided at an input stage and an amplifier circuit at a post stage. In the differential amplifier circuit, first and third bipolar transistors are PNP-type bipolar transistors and Darlington-connected. An inverting input terminal is connected to the base terminal of the first bipolar transistor. The first and third bipolar transistors and second and fourth bipolar transistors construct an input differential pair. First and second protection diodes are connected between the base terminals of the first and second bipolar transistors constructing the input differential pair and the ground potential, respectively. Each of the protection diodes is connected so that the cathode terminal is positioned on the base terminal side of the bipolar transistor, and the cathode terminal is positioned on the ground potential side.

Abstract: An operational amplifier includes a differential amplifier circuit provided at an input stage and an amplifier circuit at a post stage. In the differential amplifier circuit, first and third bipolar transistors are PNP-type bipolar transistors and Darlington-connected. An inverting input terminal is connected to the base terminal of the first bipolar transistor. The first and third bipolar transistors and second and fourth bipolar transistors construct an input differential pair. First and second protection diodes are connected between the base terminals of the first and second bipolar transistors constructing the input differential pair and the ground potential, respectively. Each of the protection diodes is connected so that the cathode terminal is positioned on the base terminal side of the bipolar transistor, and the cathode terminal is positioned on the ground potential side.

Abstract: An operational amplifier includes a differential amplifier circuit provided at an input stage and an amplifier circuit at a post stage. In the differential amplifier circuit, first and third bipolar transistors are PNP-type bipolar transistors and Darlington-connected. An inverting input terminal is connected to the base terminal of the first bipolar transistor. The first and third bipolar transistors and second and fourth bipolar transistors construct an input differential pair. First and second protection diodes are connected between the base terminals of the first and second bipolar transistors constructing the input differential pair and the ground potential, respectively. Each of the protection diodes is connected so that the cathode terminal is positioned on the base terminal side of the bipolar transistor, and the cathode terminal is positioned on the ground potential side.

Abstract: An operational amplifier includes a differential amplifier circuit provided at an input stage and an amplifier circuit at a post stage. In the differential amplifier circuit, first and third bipolar transistors are PNP-type bipolar transistors and Darlington-connected. An inverting input terminal is connected to the base terminal of the first bipolar transistor. The first and third bipolar transistors and second and fourth bipolar transistors construct an input differential pair. First and second protection diodes are connected between the base terminals of the first and second bipolar transistors constructing the input differential pair and the ground potential, respectively. Each of the protection diodes is connected so that the cathode terminal is positioned on the base terminal side of the bipolar transistor, and the cathode terminal is positioned on the ground potential side.