Abstract: A electric power conversion unit generates a DC output according to a pulse signal from a PWM unit. An A/D conversion unit converts the output voltage from the electric power conversion unit into digital data. A digital filter amplifies the difference between the digital data output from the A/D conversion unit and a reference value. A pulse width computation unit computes the on-time of a pulse signal provided to the electric power conversion unit based on the output from the digital filter. The on-time is written to an on-time register. The PWM unit generates a pulse signal according to the cycle set in a cycle register and the on-time written to the on-time register, and provides the signal to the electric power conversion unit.

Abstract: The DC output of a power conversion unit is controlled based on a pulse signal generated by a PWM unit. An operations unit detects an output current Iout, and determines the operation mode of a load based on the detected current value. When the output current Iout is weak, a value smaller than usual is written to a cycle register. The PWM unit generates a pulse signal according to the data stored in the cycle register and an on-time register.

Abstract: The DC output of a power conversion unit is controlled based on a pulse signal generated by a PWM unit. An operations unit detects an output current Iout, and determines the operation mode of a load based on the detected current value. When the output current Iout is weak, a value smaller than usual is written to a cycle register. The PWM unit generates a pulse signal according to the data stored in the cycle register and an on-time register.

Abstract: A synchronous rectifying type DC-DC converter including an auxiliary winding, provided on a secondary side of a transformer, for supplying voltages assuming polarities opposite to each other to control terminals of a rectifying switch and of a fly wheel switch, and the rectifying switch and the fly wheel switch are so constructed as not to be turned ON/OFF by a voltage generated on a supply path of an electric current to a load from a secondary winding of the transformer. When connecting a plurality of DC-DC converters in parallel and operating these converters in parallel, an output of any one of the converters stops, and, even if outputs of the other DC-DC converters are inputted to the DC-DC converter concerned and the electric current flows into the current supply path, a voltage based on the above current is not applied to control terminals of the rectifying switch and of the fly wheel switch. The rectifying switch and the fly wheel switch are not therefore turned ON.

Abstract: The DC output of a power conversion unit is controlled based on a pulse signal generated by a PWM unit. An operations unit detects an output current Iout, and determines the operation mode of a load based on the detected current value. When the output current Iout is weak, a value smaller than usual is written to a cycle register. The PWM unit generates a pulse signal according to the data stored in the cycle register and an on-time register.

Abstract: A switching power supply unit controls an output voltage of a power supply without monitoring an output voltage. The switching power supply unit includes a pulse width modulator for generating a control signal to turn on and off a switching transistor. A central processing unit outputs a modulation signal to control the pulse width modulator while sensors detect an input voltage, an output current and a peripheral temperature. A table is used by the central processing unit to store information about a relation between the detected values from the sensors and an ON time of the switching transistor. The central processing unit then selects an ON time of the switching transistor from the table according to values detected by the respective sensors to thereby provide control for switching the switching transistor on and off.

Abstract: A redundant power supply system so contrived that, upon occurrence of a fault in any one power unit, the other power unit is capable of performing relief power supply to a load. The power supply system comprises an AC-DC converter for converting an AC voltage to a DC voltage, and a plurality of power units connected in parallel to the output side of the AC-DC converter. Each of the power units includes a power source for feeding the load with a stable DC output corresponding to the DC voltage; a fuse connected to the input side of the power source for cutting off a power line; a coil connected in series to the fuse; and a capacitor connected between a line, which is disposed between the fuse and the coil, and another line between the output side of the AC-DC converter and the input side of the power source.

Abstract: Disclosed is a synchronous rectifier type DC-to-DC converter capable of preventing an increase in losses occurring when a rectifier synchronous rectification switch and a flywheel synchronous rectification switch, which are responsible for rectification on the side of a secondary winding of a transformer, are turned on simultaneously, and the destruction of FETs or windings due to large currents. The DC-to-DC converter comprises a transformer, a primary switching device connected in series with a primary winding of the transformer, a control circuit for controlling turning on or off of the primary switching device, a rectifier synchronous rectification switching device, and a flywheel synchronous rectification switching device, and converts a voltage of a DC power source into another voltage.

Abstract: The present invention relates to a DC-DC converter, and aims at preventing a flywheel switch from being destroyed. A PWM control circuit outputs an oscillation signal in order to alternately switch between a main switch and a rectification switch, and a flywheel switch. A state detecting unit generates a control instruction signal for a controlling unit, if the DC-DC converter is powered down or if it is overloaded. The controlling unit turns off the flywheel switch by controlling a driving circuit which controls the on/off status of the flywheel switch. An electric current I.sub.Q2 flows via a parasitic diode D.sub.Q2, when the flywheel switch is turned off. With the above described configuration, the flywheel switch can be prevented from being destroyed, when the DC-DC converter is overloaded, or when an overcurrent occurs due to power-down.

Abstract: The apparatus of the present invention has an interface circuit which returns power in H-level output state, a first power circuit supplying a first supply voltage, and a second power circuit supplying a second supply voltage. The second power circuit receives the entered first supply voltage from the first power circuit, and in a first operation mode (L-level output condition), brings the first supply voltage of 3.3 V down to the second supply voltage of 1.5 V and supplies same to the interface circuit. In a second operation mode (H-level output condition) of the load circuit, a current output from the load circuit is brought up to the first supply voltage of 3.3 V and feeds same back to the first power circuit.