Abstract: A reference voltage generating circuit generates a reference voltage Vref. An A/D converting circuit compares an analog input voltage Vin with the reference voltage Vref to convert the analog input voltage Vin to a digital output value Dout. A measured value storing circuit stores a measured value of the reference voltage Vref in advance and outputs the stored measured value. A user of an A/D converter corrects the digital output value Dout from the A/D converting circuit by use of the measured value of the reference voltage Vref outputted from the measured value storing circuit, thereby obtaining a digital value representing the analog input voltage Vin accurately irrespective of the accuracy of the reference voltage Vref.

Abstract: A method for controlling a DC-DC converter that achieves high conversion efficiency without using a linear regulator circuit. The DC-DC converter includes a main switching transistor, a first capacitor, a second capacitor, and a diode that is series-connected to the first capacitor. The series-connected diode and the first capacitor are connected between the source and drain of the main switching transistor. The second capacitor is connected in parallel to the first capacitor or disconnected from the first capacitor in synchronism with activation and inactivation of the main switching transistor to generate gate voltage for driving the main switching transistor.

Abstract: A reference voltage generating circuit generates a reference voltage Vref. An A/D converting circuit compares an analog input voltage Vin with the reference voltage Vref to convert the analog input voltage Vin to a digital output value Dout. A measured value storing circuit stores a measured value of the reference voltage Vref in advance and outputs the stored measured value. A user of an A/D converter corrects the digital output value Dout from the A/D converting circuit by use of the measured value of the reference voltage Vref outputted from the measured value storing circuit, thereby obtaining a digital value representing the analog input voltage Vin accurately irrespective of the accuracy of the reference voltage Vref.

Abstract: A self-excited multi-phase DC-DC converter having satisfactory responsiveness when its load suddenly changes. A control unit of the converter compares output currents of first and second converter units. Based on the comparison result, the control unit generates control signals to operate a converter unit through which a smaller output current flows. For example, when an output voltage of the converter decreases due to a sudden change in the load while the first converter unit is operating to supply current, the second converter unit through which a smaller output current flows is operated to increase the output voltage.

Abstract: A reference voltage generating circuit generates a reference voltage Vref. An A/D converting circuit compares an analog input voltage Vin with the reference voltage Vref to convert the analog input voltage Vin to a digital output value Dout. A measured value storing circuit stores a measured value of the reference voltage Vref in advance and outputs the stored measured value. A user of an A/D converter corrects the digital output value Dout from the A/D converting circuit by use of the measured value of the reference voltage Vref outputted from the measured value storing circuit, thereby obtaining a digital value representing the analog input voltage Vin accurately irrespective of the accuracy of the reference voltage Vref.

Abstract: A DC-DC converter for generating power supply voltage differing from input voltage, while operating a semiconductor circuit at a predetermined speed regardless of differences between devices or changes in the operation environment. An output voltage control circuit compares an oscillation signal, which is provided from a ring oscillator of the semiconductor circuit, with a triangular wave signal, which is provided from an oscillator of the DC-DC converter, and changes the output voltage of the DC-DC converter in accordance with the comparison result. This substantially equalizes the oscillation signal of the ring oscillator with the triangular wave signal, which functions as a reference signal, and operates the semiconductor circuit at a speed that is in accordance with the triangular wave signal.

Abstract: A DC-DC converter for controlling the order for providing a semiconductor integrated circuit device with a plurality of power supply voltages. A switch control circuit controls activation and inactivation of a transistor of the switch circuit based on the comparison result of a first voltage and a reference voltage and a notification signal provided to the switch control circuit. The switch control circuit generates a second voltage that is higher than the first voltage when the first voltage is higher than the reference voltage and the notification signal indicates that other semiconductor integrated circuit devices are ready to operate.

Abstract: A portable device for preventing overcharging of a secondary battery resulting from contact failure of a voltage detection terminal. The portable device includes a charging circuit for charging the secondary battery when a battery pack, which includes the secondary battery, is connected to the portable device. The charging circuit includes a charging terminal, which is used to supply the secondary battery with charging current, and a voltage detection terminal, which is used to detect voltage of the secondary battery. The charging circuit stops charging the secondary battery when voltage abnormality is detected at the voltage detection terminal.

Abstract: A DC/DC converter enabling an increase in frequency. The DC/DC converter includes a main transistor, a synchronization transistor, a control circuit, which controls the main transistor and the synchronization transistor, and a capacitor, which is charged to generate gate voltage for the main transistor. The control circuit includes a charging time setting circuit for setting the activation time of the main transistor and the synchronization transistor.

Abstract: A protection method for preventing battery cells from over-discharging and being overcharged, a control circuit, and a battery unit are provided. In the protection method, when a set signal “1” is supplied to a set terminal, a flip-flop outputs “1”. The gate of a discharge control FET then becomes “1”, so that the discharge control FET is OFF regardless of a discharge control signal supplied from a voltage monitor circuit. When a reset signal “1” is supplied to a reset terminal, the flip-flop outputs “0”. The discharge control FET is then switched on and off in accordance with the output of a discharge control circuit of the voltage monitor circuit. In this manner, battery cells connected to an electronic device do not over-discharge, even when they are left unused for a long period of time. Thus, the battery unit can be prevented from deteriorating and shortening the life thereof.

Abstract: A first terminal receives an input voltage. A second terminal is connected to one end of an inductor element. A third terminal is connected to the other end of the inductor element. For example, the third terminal (the other end of the inductor element) is connected to a ground line via a capacitor element. A switch circuit connects the second terminal to one of the first terminal and a ground line. A control circuit switches a connection destination of the switch circuit according to a voltage of the third terminal in order to set the third terminal at a predetermined voltage. An internal circuit receives the voltage of the third terminal as a power supply voltage.

Abstract: A protection method for preventing battery cells from over-discharging and being overcharged, a control circuit, and a battery unit are provided. In the protection method, when a set signal “1” is supplied to a set terminal, a flip-flop outputs “1”. The gate of a discharge control FET then becomes “1”, so that the discharge control FET is OFF regardless of a discharge control signal supplied from a voltage monitor circuit. When a reset signal “1” is supplied to a reset terminal, the flip-flop outputs “0”. The discharge control FET is then switched on and off in accordance with the output of a discharge control circuit of the voltage monitor circuit. In this manner, battery cells connected to an electronic device do not over-discharge, even when they are left unused for a long period of time. Thus, the battery unit can be prevented from deteriorating and shortening the life thereof.

Abstract: A circuit for controlling charging includes a transistor provided on a charging path between a position of a charging terminal and a position of a battery, an input voltage detecting circuit configured to detect a potential of a point on the charging path coupled to the charging terminal's side of the transistor, and a drive circuit configured to control an ON resistance of the transistor between a conductive state and a nonconductive state in response to the potential detected by the input voltage detecting circuit.

Abstract: A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control, basing the conversion on a pulse width modulation control using an output of the error amplifier. The error amplifier inputs a voltage signal corresponding to an output voltage of a DC/DC result and a plurality of reference voltage signals. The DC/DC apparatus also includes a soft start capacitor to provide one of the plurality of reference voltage signals. The error amplifier amplifies a difference between the voltage signal corresponding of the output voltage of a DC/DC result and a voltage signal of a lower potential among the plurality of reference voltage signals and carries out the pulse width modulation control. Furthermore, the control circuit includes a circuit for discharging charges corresponding to the output voltage of the DC/DC result when a power supply to the control circuit is turned off.

Abstract: A reference voltage generating circuit generates a reference voltage Vref. An A/D converting circuit compares an analog input voltage Vin with the reference voltage Vref to convert the analog input voltage Vin to a digital output value Dout. A measured value storing circuit stores a measured value of the reference voltage Vref in advance and outputs the stored measured value. A user of an A/D converter corrects the digital output value Dout from the A/D converting circuit by use of the measured value of the reference voltage Vref outputted from the measured value storing circuit, thereby obtaining a digital value representing the analog input voltage Vin accurately irrespective of the accuracy of the reference voltage Vref.

Abstract: A power supply control circuit connectable with an input power monitor that monitors an input power value to the power supply, an output power monitor that monitors an output power value from the power supply, and an output power controller that varies the output power value from the power supply, the power supply control circuit having an output power determiner that determines a determined output power value depending on the input power value and a power adjuster that adjusts the output power value to the determined output power value by controlling the output power controller.

Abstract: A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control, basing the conversion on a pulse width modulation control using an output of the error amplifier. The error amplifier inputs a voltage signal corresponding to an output voltage of a DC/DC result and a plurality of reference voltage signals. The DC/DC apparatus also includes a soft start capacitor to provide one of the plurality of reference voltage signals. The error amplifier amplifies a difference between the voltage signal corresponding to the output voltage of a DC/DC result and a voltage signal of a lower potential among the plurality of reference voltage signals and carries out the pulse width modulation control. Furthermore, the control circuit includes a circuit for discharging charges corresponding to the output voltage of the DC/DC result when a power supply to the control circuit is turned off.

Abstract: A remaining charge predicting method which improves the precision of predicting the remaining charge of a rechargeable battery. A battery pack has a measuring circuit which monitors a charge current, discharge current, the voltage of the rechargeable battery and the temperature of the battery. The measuring circuit notifies a power management microcomputer, provided in a portable device, of the measured current, voltage and temperature. The power management microcomputer predicts the remaining charge of the battery based on the received measured values. The battery pack does not perform data processing for predicting the remaining charge.

Abstract: A DC/DC converter enabling an increase in frequency. The DC/DC converter includes a main transistor, a synchronization transistor, a control circuit, which controls the main transistor and the synchronization transistor, and a capacitor, which is charged to generate gate voltage for the main transistor. The control circuit includes a charging time setting circuit for setting the activation time of the main transistor and the synchronization transistor.

Abstract: A portable device for preventing overcharging of a secondary battery resulting from contact failure of a voltage detection terminal. The portable device includes a charging circuit for charging the secondary battery when a battery pack, which includes the secondary battery, is connected to the portable device. The charging circuit includes a charging terminal, which is used to supply the secondary battery with charging current, and a voltage detection terminal, which is used to detect voltage of the secondary battery. The charging circuit stops charging the secondary battery when voltage abnormality is detected at the voltage detection terminal.