Abstract: A control circuit for suppressing generation of inrush current during activation of a DC-DC converter, which controls output with control signals. The control circuit includes first and second error amplification circuits, each of which generates a control signal based on the difference between a reference voltage and voltage derived from an output voltage or an output current. During activation of the DC-DC converter, a soft start circuit generates a soft start signal having voltage lower than voltage of each control signal to control the output of the DC-DC converter. During activation of the DC-DC converter, a clamp circuit, which is connected to the first and second error amplification circuits, clamps the voltage of the first and second control signals to substantially the same voltage as the soft start signal.

Abstract: A control circuit for controlling an output voltage of a DC/DC converter. The control circuit includes a pulse signal generation circuit which generates a pulse signal for controlling the output voltage of the DC/DC converter, and a drive signal generation circuit which generates first and second drive signals using the pulse signal such that a main switching element and a synchronous switching element are turned ON and OFF alternately at different timings. The drive signal generation circuit generates the first drive signal which has substantially the same pulse width as that of the pulse signal to improve ON-duty characteristics of the main switching element.

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 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 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 control circuit for suppressing generation of inrush current during activation of a DC-DC converter, which controls output with control signals. The control circuit includes first and second error amplification circuits, each of which generates a control signal based on the difference between a reference voltage and voltage derived from an output voltage or an output current. During activation of the DC-DC converter, a soft start circuit generates a soft start signal having voltage lower than voltage of each control signal to control the output of the DC-DC converter. During activation of the DC-DC converter, a clamp circuit, which is connected to the first and second error amplification circuits, clamps the voltage of the first and second control signals to substantially the same voltage as the soft start signal.

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 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: There are provided a DC/DC converter control circuit and a DC/DC converter system having high degree of freedom of mounting and achieving the following matters: (1) housing a DC/DC converter control circuit in a package miniaturized by reducing the number of terminals; and (2) starting-up a power saving mode in response to an input of an external control signal to a DC/DC converter system. A frequency setting terminal (RT) is connected to a resistance element RT and a switching section 1 in series, between the terminal and ground voltage. An external control signal CTL is inputted to the switching section 1. When an external control signal CTL turns off the switching section 1, connection to the ground voltage is opened and an oscillation driving section 4 does not operate. Thereby, power saving mode is kept. When the switching section 1 is turned on, connection to the ground voltage is closed and the oscillation driving section 4 starts up.

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.

Abstract: A regulator circuit capable of accurately adjusting output voltage anywhere in a current region and maintaining optimum output voltage by correcting setting of a predetermined voltage to be regulated depending on a value of charging current. An output terminal of an amplifier is connected to a reference voltage terminal through a resistance element. When charging current does not flow, detection voltage 0V. Consequently, voltage of a reference power source is divided between a resistance element R1 and parallel resistance elements R2 and R3. When charging current flows and detection voltage is outputted, the detection voltage is divided by resistance elements R2 and R3, whereby corrected voltage depending on a value of charging current is generated. Even if voltage drop occurs between a charging-control-device output terminal and a battery terminal, control voltage of output voltage is appropriately adjusted so that a battery terminal can keep full charging voltage.

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 control circuit for controlling an output voltage of a DC/DC converter. The control circuit includes a pulse signal generation circuit which generates a pulse signal for controlling the output voltage of the DC/DC converter, and a drive signal generation circuit which generates first and second drive signals using the pulse signal such that a main switching element and a synchronous switching element are turned ON and OFF alternately at different timings. The drive signal generation circuit generates the first drive signal which has substantially the same pulse width as that of the pulse signal to improve ON-duty characteristics of the main switching element.

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 power supply control device, a power supply control circuit, a power supply control method, and an electronic apparatus wherein a determination is made of whether or not a switching element therein is in an ON state. When the switching element is in the ON state, a voltage generated across the switching element is detected in accordance with a current flowing through the switching element. In accordance with the detected voltage, the switching element is controlled and thereby an output voltage is controlled.

Abstract: A DC—DC converter in which no operational instability occurs and ranges of input and output voltages are wide, an electric appliance using such DC—DC converter, and a duty-ratio setting circuit in which no operational instability occurs and ranges of input and output voltages of a converter circuit can be widen in controlling the converter circuit are provided. A DC—DC converter 10 has a converter circuit 110, an output voltage detection circuit 120 and a duty-ratio setting circuit 20. An error amplifier circuit 21 compares Vref1 with Vd to output a control voltage Vfb. A pulse-width modulator circuit 25 compares a triangular-wave voltage Vct with the control voltage Vfb to output a first pulse signal PWO. A second-pulse generator circuit 26 outputs a second pulse signal PSO having a predetermined on-duty ratio.

Abstract: There is intended to provide an overvoltage-protective device capable of protecting a power system from overvoltage not destructively without using a fuse. An alarm signal from an MOS transistor Tr3, a structural element of a DC/DC converter 21, is inputted to a switching circuit 55, a structural element of the AC/DC converter 11. In case an alarm signal keeps high-level potential without indicating overvoltage-state, the switching circuit 55 connects a output current detecting circuit 53 having the smaller gain G1 to an output voltage detecting circuit 50 as well as a feedback circuit 51A, thereby to set large output-power-supply capability. In case an alarm signal inverses to low-level potential indicating overvoltage-state, the switching circuit 55 connects a output current detecting circuit 54 having the larger gain G2 to the output voltage detecting circuit 50 as well as the feedback circuit 51A, thereby to set small output-power-supply capability.

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.