Abstract: A switching device driving apparatus has a driver for controlling, according to an input signal, the on/off states of a pair of field-effect transistors connected in series between a first supply voltage and a second supply voltage lower than the first supply voltage, and a detector for detecting the on/off states of body diodes attached respectively to the field-effect transistors. Only after either of the body diodes is detected being on are the field-effect transistors respectively turned on to produce an output corresponding to the input signal. This makes it possible to securely prevent the two FETs from being turned on simultaneously independently of their characteristics and type.

Abstract: A power supply unit (system power supply IC) has a multiplicity of power supply circuits providing for different supply voltages. Should an abnormal condition take place in any of the multiple power supply circuits, the power supply circuit suffering the abnormality issues an abnormality detection signal that contains a power supply circuit number and an abnormality type, which signal is stored in a nonvolatile memory together with time data indicative of the time of reception of the abnormality detection signal before all the power supply circuits are disabled. Thus, this arrangement protects the system power supply IC and the loads connected thereto, and provides convenient means for analyzing the abnormality and replicating it if necessary, based on the abnormal power supply circuit number, abnormality type and time data stored in the nonvolatile memory.

Abstract: The power supply unit is provided with a power supply circuit adapted to generate an output voltage in accord with an instruction voltage, an output condenser Co connected to the output end of the power supply circuit, and an auxiliary output voltage setting circuit adapted to compare the instruction voltage and the output voltage and to cause the output condenser to discharge its electric charge when the instruction voltage becomes lower than the output voltage. Because of the auxiliary output voltage setting circuit, the power supply circuit quickly generates an output voltage in accord with the instruction voltage if the instruction voltage is lowered.

Abstract: A switching power supply unit generates a pulse signal having a duty factor based on the voltage associated with the difference between a reference voltage and the output voltage of the unit, and the voltage associated with the current flowing through a smoothing coil. Upon receipt of the pulse signal and a light-load determination signal, a delay-control unit of the power supply unit outputs as an instruction signal supplied to the switching circuit the pulse signal as it is when the light-load determination signal indicates that the load is not light, but otherwise outputs the pulse signal after delaying and widening the pulse width thereof. Thus, when the load is light, the switching power supply unit may hold its switching frequency substantially low and constant without rendering the frequency bursting discontinuously.

Abstract: In a multiphase DC/DC converter having a plurality of DC/DC converters, to prevent faults in the circuit and the circuit elements constituting it even when the balance of current limiting operation among the individual DC/DC converters is disturbed due to individual and temperature-related variations in the characteristics of the circuit elements, the output currents of the individual DC/DC converters are detected and added together, and are limited individually so that their sum does not exceed a predetermined level of current.

Abstract: A power supply device has a reference voltage generator for generating a reference voltage, a monitor voltage generator for generating a monitor voltage that varies according to an output voltage, an output controller for producing the output voltage from an input voltage in such a way that the monitor voltage is kept equal to the reference voltage and then supplying the output voltage to a load, and a reference voltage adjuster for varying the reference voltage according to the monitor voltage. This makes it possible to reduce, with a simple configuration, variation in the output voltage resulting from variation in the power source or the load.

Abstract: A DC—DC converter supplied with a power from a DC power source having a predetermined power source voltage, for controlling an output voltage of the DC—DC converter such that the output voltage becomes an aimed output voltage, by switching a transistor with a pulse having a predetermined width when the output voltage is lower than the aimed output voltage and stopping the switching operation of the transistor when the output voltage exceeds the aimed output voltage, comprises a variable duty cycle pulse generator circuit for generating a pulse having duty cycle determined by a ratio of the power source voltage to the aimed output voltage, a switch circuit for outputting the pulse as a switching pulse of the transistor when the switch circuit is turned ON and a control circuit for turning the switch circuit ON when the output voltage is lower than the aimed outut voltage.

Abstract: In the present invention, an amplitude of a triangular wave from a triangular wave generating circuit is controlled depending on a power source voltage and further the current value for charging and discharging a capacitor is also controlled depending on the amplitude in such a manner that when the power source voltage drops the frequency of the triangular wave to be outputted is maintained at a predetermined frequency by reducing the current value and the amplitude and the waveform gradient is reduced. Accordingly, a variation range of PWM pulse width can be enlarged with respect to the variation of error voltage and a sufficient control capacity can be achieved with respect to the output voltage variation when the power source voltage drops.

Abstract: In the present invention, an amplitude of a triangular wave from a triangular wave generating circuit is controlled depending on a power source voltage and further the current value for charging and discharging a capacitor is also controlled depending on the amplitude in such a manner that when the power source voltage drops the frequency of the triangular wave to be outputted is maintained at a predetermined frequency by reducing the current value and the amplitude and the waveform gradient is reduced. Accordingly, a variation range of PWM pulse width can be enlarged with respect to the variation of error voltage and a sufficient control capacity can be achieved with respect to the output voltage variation when the power source voltage drops.

Abstract: A DC-DC converter supplied with a power from a DC power source having a predetermined power source voltage, for controlling an output voltage of the DC-DC converter such that the output voltage becomes an aimed output voltage, by switching a transistor with a pulse having a predetermined width when the output voltage is lower than the aimed output voltage and stopping the switching operation of the transistor when the output voltage exceeds the aimed output voltage, comprises a variable duty cycle pulse generator circuit for generating a pulse having duty cycle determined by a ratio of the power source voltage to the aimed output voltage, a switch circuit for outputting the pulse as a switching pulse of the transistor when the switch circuit is turned ON and a control circuit for turning the switch circuit ON when the output voltage is lower than the aimed outut voltage.

Abstract: A switching regulator includes a series circuit of a resistor, a diode and a speed-up capacitor, connected in parallel to a voltage dividing resistor of a voltage dividing resistor circuit for output voltage detection, which is connected to an output terminal of the switching regulator.

Abstract: A switching regulator includes a series circuit of a resistor, a diode and a speed-up capacitor, connected in parallel to a voltage dividing resistor of a voltage dividing resistor circuit for output voltage detection, which is connected to an output terminal of the switching regulator.