Abstract: A DC-DC converter for converting an input voltage and generating an output voltage. The DC-DC converter includes an adjustment resistor. A control circuit generates a control signal and includes an external terminal to which the adjustment resistor is externally connected. A switching transistor is connected to the control circuit and turned on or off in accordance with the control signal. The control circuit includes an oscillator that generates an oscillation signal. The control circuit generates the control signal based on the oscillation signal and a signal that is in accordance with an output voltage or output current of the DC-DC converter. The oscillator monitors a first amount of current flowing through the external terminal of the control circuit and generates the oscillation signal in a cycle that is accordance with the monitoring result.

Abstract: To present a DC-DC converter efficient in conversion and not requiring an external diode. The DC-DC converter includes a main NMOS transistor FET1 as a main switching device, a driver DVH1 for driving a gate terminal of the main NMOS transistor FET1, a capacitor C2 connected between a source terminal of the main NMOS transistor FET1 and a power source terminal of the driver DVH1, and an NMOS transistor FET3 connected between a route leading to an input power source and the power source terminal of the driver DVH1. The NMOS transistor FET3 does not conduct when the main NMOS transistor FET1 conducts, and conducts when the main NMOS transistor FET1 does not conduct.

Abstract: To present a DC-DC converter efficient in conversion and not requiring an external diode. The DC-DC converter includes a main NMOS transistor FET1 as a main switching device, a driver DVH1 for driving a gate terminal of the main NMOS transistor FET1, a capacitor C2 connected between a source terminal of the main NMOS transistor FET1 and a power source terminal of the driver DVH1, and an NMOS transistor FET3 connected between a route leading to an input power source and the power source terminal of the driver DVH1. The NMOS transistor FET3 does not conduct when the main NMOS transistor FET1 conducts, and conducts when the main NMOS transistor FET1 does not conduct.

Abstract: A DC-DC converter for converting an input voltage and generating an output voltage. The DC-DC converter includes an adjustment resistor. A control circuit generates a control signal and includes an external terminal to which the adjustment resistor is externally connected. A switching transistor is connected to the control circuit and turned on or off in accordance with the control signal. The control circuit includes an oscillator that generates an oscillation signal. The control circuit generates the control signal based on the oscillation signal and a signal that is in accordance with an output voltage or output current of the DC-DC converter. The oscillator monitors a first amount of current flowing through the external terminal of the control circuit and generates the oscillation signal in a cycle that is accordance with the monitoring result.

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: 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: An oscillator circuit for efficiently generating a triangular wave signal having multiple phases. The oscillator circuit includes capacitors, each having two terminals and having a voltage between the two terminals. The capacitors include a first capacitor. A plurality of charge/discharge switching circuits are connected to the first capacitor. Each of the charge/discharge switching circuits generates a switching signal for an associated one of the switches to control the charging and discharging of the associated capacitor. The switching signals of the charge/discharge switching circuits have different phases. Each of the charge/discharge switching circuits receives a first capacitor voltage between the terminals of the first capacitor and compares the first capacitor voltage with a first reference voltage and a second reference voltage to generate the switching signal that has a predetermined phase. A triangular wave signal is generated at one of the two terminals of each of the capacitors.

Abstract: There is provided a regulator circuit capable of accurately adjusting output voltage anywhere in a current region and maintaining optimum output voltage by correcting setting of predetermined voltage to be regulated depending on a value of charging current. An output terminal V3 of an amplifier 112 is connected to a reference voltage terminal V2 through a resistance element R3. In case charging current ICHG does not flow, detection voltage V3 is 0V. Consequently, voltage of reference power source VREF is divided between a resistance element R1 and parallel resistances namely, resistance elements R2 and R3 in a meaning of electrical potential. In case the charging current ICHG flows and detection voltage V3 is outputted, the detection voltage V3 is divided by the resistance elements R3 and R2, whereby a corrected voltage depending on a value of the charging current ICHG is generated.

Abstract: An oscillator circuit for efficiently generating a triangular wave signal having multiple phases. The oscillator circuit includes capacitors, each having two terminals and having a voltage between the two terminals. The capacitors include a first capacitor. A plurality of charge/discharge switching circuits are connected to the first capacitor. Each of the charge/discharge switching circuits generates a switching signal for an associated one of the switches to control the charging and discharging of the associated capacitor. The switching signals of the charge/discharge switching circuits have different phases. Each of the charge/discharge switching circuits receives a first capacitor voltage between the terminals of the first capacitor and compares the first capacitor voltage with a first reference voltage and a second reference voltage to generate the switching signal that has a predetermined phase. A triangular wave signal is generated at one of the two terminals of each of the capacitors.

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 DC-DC converter generally includes a supply circuit, a charge circuit, and a control unit connected to the charge circuit. The charge circuit receives the input current and supplying a charge current to the battery. The control unit controls the charge current according to the results of comparisons between various currents and voltages and corresponding threshold levels. The control unit, which may be constructed on a single-chip semiconductor substrate, includes a differential charge controller, a charge current controller, a charge voltage controller, and a dynamic charge controller. These elements respectively compare the input current, the charge current, the charge voltage and an input voltage from the external DC power supply with a threshold values and control the charge current and charge voltage according to a result of the comparisons.

Abstract: A DC-DC converter generally includes a supply circuit, a charge circuit, and a control unit connected to the charge circuit. The charge circuit receives the input current and supplying a charge current to the battery. The control unit controls the charge current according to the results of comparisons between various currents and voltages and corresponding threshold levels. The control unit, which may be constructed on a single-chip semiconductor substrate, includes a differential charge controller, a charge current controller, a charge voltage controller, and a dynamic charge controller. These elements respectively compare the input current, the charge current, the charge voltage and an input voltage from the external DC power supply with a threshold values and control the charge current and charge voltage according to a result of the comparisons.

Abstract: A DC-DC converter includes a main switching device and a synchronous switching connected in series between a power supply and a ground, and a drive control circuit for supplying a first drive signal to the main switching device and a second drive signal to the synchronous switching device to alternately activate and deactivate the main switching device and the synchronous switching device. A detection circuit is connected to the synchronous switching device for detecting a malfunction of the synchronous switching device, such as a short-circuit, and generates a detection signal when a malfunction is detected. A protection circuit is connected to the detection circuit and the drive control circuit and inhibits the first and second drive signals in response to the detection signal. The drive control circuit, the detection circuit and the protection circuit are all formed on a single semiconductor substrate.

Abstract: A duty ratio setting circuit includes a triangular waveform oscillation circuit for generating a triangular waveform signal and an error amplifying circuit that compares a detection voltage with a reference voltage and generates a control voltage based on the difference between the compared voltages. A comparator is connected to the oscillation circuit and the amplifying circuit and compares the voltage of the triangular waveform signal with the control voltage, and generates a first rectangular waveform signal having a predetermined duty ratio based on the comparison. A pulse signal generator generates a pulse signal having a predetermined pulse width and which is synchronized with the triangular waveform signal. A logic circuit connected to the comparator and the pulse signal generator receives the first rectangular waveform signal and the pulse signal and generates a second rectangular waveform signal.