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: 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: 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: 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: 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 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 DC--DC converter includes an offset comparator that compares an output voltage with a reference voltage in parallel with an error amplification circuit, which also compares the output voltage with the reference voltage. The offset comparator has a predetermined offset voltage set between its input terminals so that the offset comparator outputs a high signal when the voltage difference between its inputs exceeds the predetermined level. The output of the offset comparator is input, along with the error amplification circuit output, into a PWM comparator. The signal output by the offset voltage comparator allows the DC--DC converter to more quickly respond to a sudden increase in current consumption by a connected load. In responding to the increased current draw, the DC--DC converter quickly converges back at the reference voltage, such that the DC--DC converter provides a very stable output voltage.

Abstract: A control circuit for controlling an output voltage of a DC--DC converter which supplies power to various semiconductor device, such as a processor and a memory, by way of an output transistor. The control circuit drives the output transistor in response to an external control signal. The control circuit gradually reduces an operating time of the output transistor by performing a discharge operation in response to the external control signal being inactive.

Abstract: A charging apparatus having a power supply circuit that provides a DC output current via a sense resistor. A current detector amplifies, detects and provides a voltage across the sense resistor. A controller designates the output of the current detector as a determination signal when the DC output current is equal to a preset voltage. Responsive to the determination signal, the controller generates a control signal in order to control the DC output current of the power supply circuit. More particularly, the current detector includes a first differential amplifier that amplifies and output the voltage across the sense resistor, a second differential amplifier amplifies and supplies a differential voltage between the output of the first differential amplifier and a predetermined first reference voltage, and a first output circuit responsive to the output of the second differential amplifier delivers the determination signal.

Abstract: A reference power supply includes an amplifier having an output terminal and a reference voltage source for providing the amplifier with a constant voltage. The amplifier amplifies the constant voltage to produce a load-driving reference voltage at the output terminal. The amplifier includes first and second constant current sources and a first transistor as an output transistor having an emitter connected to a high-potential power supply, a collector connected to the output terminal and a base connected to the second constant current source. A resistor circuit is provided between the collector of the first transistor and the low-potential power supply. The amplifier also includes first, second and third current mirror circuits. The first current mirror circuit has second and third transistors. The second transistor has an emitter connected to the resistor circuit and the third transistor has an emitter connected to the reference voltage source.

Abstract: A differential amplifier comprises a pair of current mirror circuits, a pair of constant current supplies and a pair of differential amplifier circuits. The first differential amplifier circuit is provided between the first current mirror circuit and the first constant current supply. The second differential amplifier circuit is positioned between the second constant current supply and the second current mirror circuit. The second differential amplifier circuit includes a pair of multicollector pnp transistors each having a first one of its collectors connected to the second current mirror circuit and a second one of its collectors connected to the second power supply.