Abstract: When starting charging of an internal battery as a result of connection of an external power source by an AC adapter, a charging control unit sets a first charging voltage at which the charging capacity of the internal battery is maximized. When starting the charging from recognition of reduced capacity of the internal battery due to its self-discharge in desk-top use where the AC adapter is in connection at all times, the charging control unit sets a second charging voltage lower than the first charging voltage to prevent the battery from degrading.

Abstract: In a DC-DC converter circuit having a plurality of input terminals connected to a plurality of DC power supplies, and an output terminal, the DC-DC converter circuit includes a power supply selection section for selecting a DC power supply of lowest voltage on the condition that the voltage is not less than a predetermined voltage, and a step-down type of regulator section for converting the voltage of the DC power supply selected by the power supply selection section into a predetermined voltage lower than the voltage of the DC power supply selected by the power supply selection section, and outputting the converted voltage through the output terminal.

Abstract: A DC-to-DC converter circuit having a power saving mode, and which achieves a high conversion efficiency without using a sense resistance. The DC-to-DC converter circuit includes a triangular wave generation circuit to generate a triangular wave signal and a differential amplifier to receive the triangular wave signal and to generate an output signal. A main switching element is provided to turn ON and OFF an input voltage, and a synchronous commutating switching element is provided to perform synchronous commutation of a load current. A detection device detects whether an output voltage of the main switching element is larger than an input voltage of the main switching element. A control device operates in a power saving mode to reduce a drive voltage of the main switching element in response to the detection device detecting that the output voltage of the main switching element is larger than the input voltage.

Abstract: A power unit having a built-in battery to supply voltage from the battery over a long period of time by utilizing fully the capabilities of the built-in battery. The power unit supplies electric power to a load even when a battery with a higher battery voltage than the external power source voltage is used by charging the battery from an external power source even when the external power source voltage is lower than the battery voltage. By charging the battery when electric power is supplied to a load from an external power source, the power unit supplies electric power to the load from the battery when the supply of electricity from an external power source is cut off. The power unit includes a having converter to boost output voltage from the battery and to supply the voltage to the load when the battery is discharged and the external power source voltage is higher than the battery voltage.

Abstract: In a DC-DC converter circuit having a plurality of input terminals connected to a plurality of DC power supplies, and an output terminal, the DC-DC converter circuit includes a power supply selection section for selecting a DC power supply of lowest voltage on the condition that the voltage is not less than a predetermined voltage, and a step-down type of regulator section for converting the voltage of the DC power supply selected by the power supply selection section into a predetermined voltage lower than the voltage of the DC power supply selected by the power supply selection section, and outputting the converted voltage through the output terminal.

Abstract: A power control circuit for controlling an output of a power supply is provided with a setting section which variably sets a maximum rated output based on input temperature information.

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 power control circuit for controlling an output of a power supply is provided with a setting section which variably sets a maximum rated output based on input temperature information.

Abstract: In a battery pack, which is mounted on a portable type of electronic apparatus such as a note type of personal computer, a PDA, a mobile personal computer, or another type of electronic apparatus, a pseudo battery pack modeled on the battery pack, an electronic apparatus, and an electronic apparatus system, there is provided a pseudo battery pack incorporating therein a capacitor, which is of the same type as a battery pack.

Abstract: A power unit having a built-in battery to supply voltage from the battery over a long period of time by utilizing fully the capabilities of the built-in battery. The power unit supplies electric power to a load even when a battery with a higher battery voltage than the external power source voltage is used by charging the battery from an external power source even when the external power source voltage is lower than the battery voltage. By charging the battery when electric power is supplied to a load from an external power source, the power unit supplies electric power to the load from the battery when the supply of electricity from an external power source is cut off. The power unit includes a having converter to boost output voltage from the battery and to supply the voltage to the load when the battery is discharged and the external power source voltage is higher than the battery voltage.

Abstract: A battery unit includes a plurality of cells connected in parallel with one another, and a switch connected in series with at least one of the cells. The battery unit further includes a control circuit for controlling the on or off state of the switch, and a voltage detection terminal at which a voltage produced by a cell, to which the switch is connected, is developed. The switch can be turned off even with the battery unit connected to a load. A cell in series with which the switch is connected is disconnected from the load. In this state, the state of the cell can be detected through the voltage detection terminal. Even when a resistor is substituted for the switch, the same advantage can be provided. Moreover, the battery unit is freely detachably attached to a main unit of an information processing apparatus. The battery unit then supplies power to the main unit. A power supply control circuit for requesting notification of the state of each cell in the battery unit is incorporated in the main unit.

Abstract: To avoid burning out a capacitor in a synchronous rectification type DC-to-DC converter due to overvoltages, the synchronous rectification type DC-to-DC converter includes a storage unit storing therein power derived from a power supply, switching elements connecting and disconnecting respective signal paths from power and ground, and a control unit controlling the connecting/disconnecting operations of the switching elements to maintain a voltage output from the storage unit at a predetermined value.

Abstract: A DC—DC converter generates a system output current and a battery charging current. The converter has an output transistor connected between an AC adapter, which provides a supply current, and a terminal at which the battery charging current is provided. A control circuit generates a duty control signal used to activate and deactivate the output transistor in order to adjust the battery charging current. The control circuit includes a voltage detection circuit that compares a DC power supply voltage of the AC adapter with a first reference voltage and generates a differential voltage signal from the comparison result. A PWM comparison circuit is connected to the voltage detection circuit and compares the differential voltage signal with a triangular wave signal to generate the duty control signal which has a duty ratio corresponding to the comparison result.

Abstract: A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control and controlling a direct-current to direct-current conversion based 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, based on the amplified output, carries out the pulse width modulation control.

Abstract: A protection circuit is used for a battery unit which has a plurality of cell parts coupled in parallel, and first and second power supplying terminals, where each of the cell parts includes a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals. The protection circuit includes a plurality of switching elements making an electrical connection to the first terminal of a corresponding one of the cell parts and the first power supplying terminal, and disconnecting the electrical connection in response to an active signal, and a voltage monitoring circuit outputting the active signal to the switching elements when a voltage of at least one battery cell within one cell part falls outside a predetermined range, independently with respect to each of the cell parts.

Abstract: To avoid burning out a capacitor in a synchronous rectification type DC-to-DC converter due to overvoltages, the synchronous rectification type DC-to-DC converter includes a storage unit storing therein power derived from a power supply, switching elements connecting and disconnecting respective signal paths from power and ground, and a control unit controlling the connecting/disconnecting operations of the switching elements to maintain a voltage output from the storage unit at a predetermined value.

Abstract: To avoid burning out a capacitor in a synchronous rectification type DC-to-DC converter due to overvoltages, the synchronous rectification type DC-to-DC converter includes a storage unit storing therein power derived from a power supply, switching elements connecting and disconnecting respective signal paths from power and ground, and a control unit controlling the connecting/disconnecting operations of the switching elements to maintain a voltage output from the storage unit at a predetermined value.

Abstract: A battery capacity predicting method predicts a remaining capacity of a battery unit including a plurality of battery cells connected in series in an apparatus which uses the battery unit. The battery capacity predicting method includes the steps of comparing output voltages of each of the battery cells, and predicting the remaining capacity of the battery unit based on at least one of a minimum voltage and a maximum voltage out of the compared output voltages of the battery cells.

Abstract: A charging-and-discharging device in an electronic apparatus includes a rechargeable battery and a charging device for charging the battery. The charging-and-discharging device includes a switching circuit electrically isolating one terminal side of the battery from a ground side of the electronic apparatus. The charging-and-discharging device further includes a charge control section controlling the isolating of the one terminal side of the battery from the ground side of the electronic apparatus by turning off the switching circuit during charging of the battery. In the charging-and-discharging device, the one terminal side of the battery is isolated from the ground side of the electronic apparatus by the switching circuit during charging of the battery and a closed loop including the charging device and the battery is established to charge the battery.

Abstract: In a power supply apparatus including a plurality of batteries and a plurality of power supply portions for connecting to loads, a plurality of switches connect these batteries to these power supply portions, respectively. The apparatus further includes a control mechanism which controls the opening and closing operations of the switches. When one of the switches is turned on in one of the power supply means, the control mechanism executes the control in such a manner that the other switches are turned off. The control mechanism further controls each of the switches on the basis of the remaining capacity of each battery and the load state of each power supply portion. Accordingly, the power supply operation can be flexibly carried out.