Abstract: An information processing apparatus employs a liquid crystal display and a fluorescent lamp for backlighting the screen of the liquid crystal display. A lighting circuit for supplying alternating current lighting power to the fluorescent lamp receives input power from either a commercial alternating current power source or from a direct current battery. The level of the lighting power supplied to the fluorescent lamp is determined based upon a determination of whether the input power is being supplied from the commercial power source or from the battery.

Abstract: A power source having a first rectifier, a transformer having a primary coil and a secondary coil, switching elements having one end thereof connected to one of the terminals of the primary coil, a capacitor connected between other ends of the switching elements, diodes respectively connected between the terminals of the primary coil and the other ends of the switching elements, a choke coil for supplying the input DC voltage from the first rectifier directly to one of the terminals of the primary coil, and a second rectifier for supplying an output DC voltage to a load by rectifying the output AC voltage from the secondary coil.

Abstract: A power supply control system including a variable power converter for converting electric power from a power supply to a load into that of a specification required by the load in response to a power specification information source provided on the load side. With a change in the load, the information source also changes, thereby providing a flexible power supply control system capable of meeting different loads. For applications to a high power supply, the system comprises a plurality of variable power converters adapted to operate selectively in accordance with requisite power information sources provided in or on the side of a plurality of loads, thereby providing a system realizing a flexible power supply. For application to a low power supply, the system comprises a plug having a power specification information source and a socket having a variable power converter.

Abstract: A three-phase bridge inverter for controlling a motor with a variable speed includes a drive circuit therefor and an overcurrent protection circuit on one integrated chip. The inverter IC can be operated by directly inputting a direct current obtained by rectifying commercial 100 V. Thus, the inverter chip reduces the size and the weight of a system, improves the usability, lowers the cost thereof and permits mass production fabrication. Also, the life of the IC is increased by detecting current flowing through the inverter and the temperature of the chip and stopping the operation, when an abnormality is found.

Abstract: In a module using a high-speed switching element such as an IGBT for a high-speed inverter, a matching condition is established between the switching characteristic of the IGBT and the recovery characteristic of the diode to be connected thereto in an anti-parallel fashion. As a result, the oscillating voltage appearing in the inverter circuit is suppressed to prevent erroneous operation of the inverter system.

Abstract: A semiconductor integrated circuit unit, suitable for the control of a motor, has an integrated structure within the same semiconductor substrate, comprising an inverter circuit, drive circuits for driving the switching elements of the inverter circuit, an internal power source circuit for supplying power to the drive circuits which drive the upper arm side of the inverter circuit, and a logical circuit for transmitting a signal to the drive circuits which drive the upper arm side of the inverter circuit.

Abstract: An inverter includes first, second, and third dc voltage sources, first and second switching elements which are connected in series to the first dc voltage source, a signal generator section for producing first and second control signals on the basis of the output voltage from the third dc voltage source, first and second signal level converter sections for converting voltage levels of the first and second control signals based on the output voltage from the second dc voltage source and thereby respectively generating first and second output signals, and first and second driver sections responsive to the first and second output signals for supplying the first and second switching element with first and second driving signals on the basis of the output voltage from the second dc voltage source and thereby respectively turning the first and second switching elements on or off.

Abstract: The switching of upper and lower switching elements is controlled by respective upper and lower arm driving circuits. Those switching elements are connected in series across a primary d.c. power source and their successive switching generates a drive voltage which is applied to a load. A secondary d.c. power source is connected to the lower arm driving circuit while the upper arm driving circuit is connected to a capacitor connected to the high potential side of the primary d.c. power source. The capacitor is charged from the secondary d.c. power source through a charging circuit. This driving arrangement is particularly applicable to multi-phase driving circuits.

Abstract: In order to provide miniaturization and increased-frequency operation of a DC-DC converter used with a computer, etc., a capacitor is connected in parallel with a switching element when the switching element is turned off to reduce turn-off loss. When the switching element is turned on, the capacitor and a DC power source are connected in series to supply the energy stored in the capacitor to a load circuit to result in a high initial voltage being applied across the load circuit.

Abstract: The switching of the positive (or pullup power) and negative (or pulldown power) semiconductor elements, are controlled by driving circuits which are in turn controlled by level shift circuits which have a first current control circuit and a second current control circuit coupled in parallel and this parallel connection is coupled in series with the control N-channel MOSFET of a current mirror circuit in a circuit loop arrangement with a control power supply. The first and second current control circuits are responsive to first and second control pulses of pulse widths t.sub.1 and t.sub.1 +t.sub.2, in accordance with a driving signal such that the first current control circuit supplies a first current level to the control N-channel MOSFET during the first time period t.sub.1 and the second current control circuit supplies a second current level, smaller than that of the first current level, thereto for a predetermined time period t.sub.1 +t.sub.

Abstract: A current sensing circuit for sensing a main current flowing through a power semiconductor element or elements, by utilizing a second current which is small in magnitude compared to the main current and varies depending on the main current, and sensing the second current through a current mirror circuit as a bias current of a differential circuit, and a function of sensing the temperature of the semiconductor element being afforded to the current sensing circuit through selection of a bias voltage.

Abstract: A monolithic integrated circuit device comprises first and second output terminals, a power switching circuit which is connected across the first and second output terminals and through which electric current is supplied to an external load from an external power source, a driving a circuit for generating a first drive signal to be supplied to the power switching circuit, and a third output terminal in electrical connection with the driving circuit for derivation of electric energy from the driving circuit as a second drive signal to be spplied to an external circuit via the third output terminal. The monolithic integrated circuit device is capable of not only controlling power supply to an external load but also driving an external circuit which may be another power switching cirtcuit cooperative with the power switching circuit in the present monolithic integrated circuit device for the purpose of controlled power supply to the external load or which may be other types of electronic circuits.

Abstract: An impedance for short-circuit prevention is connected with a secondary winding side of a transformer of a resonant converter comprising a resonant circuit, a D.C. input source, and a switching devices. The short-circuit prevention impedance is driven by the driving current generated in a driving winding in accordance with a resonance current at the primary winding side of the transformer, thereby obviating the stop of an oscillation. The oscillation can be stopped at a timing of not generating a surge voltage in the switching devices by detecting a current returning to the D.C. input power source.

Abstract: A power supply circuit comprises first charge storing means, second and third charge storing means supplying their charged voltages so as to be used as sources of predetermined voltages applied to associated loads respectively, switch means capable of selectively establishing at least a first mode and a second mode so that, in the first mode, the first and second charge storing means are connected in series with a d.c. power source to be charged by a power supply voltage, while, in the second mode, the first charge storing means is electrically isolated from the d.c. power source and the second charge storing means, and the third charge storing means is connected to the first charge storing means in a closed circuit to be charged by the charges stored in the first charge storing means, and a drive circuit driving the switch means so that the switch means repeats an operation cycle including at least the first mode and the second mode executed in that order.

Abstract: A PLL comprising a phase comparator circuit for detecting the phase of a pulse signal based upon the input signal and the phase of a pulse signal based upon the output signal, a smoothing filter for smoothing the output of the phase comparator circuit, a loop filter for controlling the oscillation frequency on the basis of the smoothing filter, and a voltage controlled oscillator circuit for sending out the output signal having a frequency corresponding to the voltage based upon the output of the loop filter. Since the smoothing filter is separated from the loop filter, time constants of the smoothing filter and the loop filter can be set independently and with precision. If the time constant of the smoothing filter is chosen to be extremely small, for example, the time constant of the phase-locked loop is defined by the time constant of the loop filter. It is thus possible to define the time constant of the phase-locked loop by only selecting the time constant of the loop filter.

Abstract: A voltage controlled oscillator is provided which includes a pair of gain stages constituting a positive feedback path, a pair of buffer stages in cross connection with the gain stages, a pair of loads connected with the corresponding gain stages, each having a parallel connection of an active device resistor and a clamping diode, and a pair of voltage controlled current sources connected with the corresponding gain stages, for supplying constant currents to the gain stages. A timing capacitor is connected with the input sides of both voltage controlled current sources, and is charged or discharged by the constant currents from the current sources.

Abstract: In a self-oscillating type switching power supply in which an input source, a primary winding of a transformer, and a switching element are connected in series, and a constant output is supplied to a load from a secondary winding of the transformer by the operation of the switching element, in order to obtain a signal to turn off the switching element, a sense circuit for detecting the output of the switching power supply is provided, and the analog signal from the sense circuit is inputted to one winding of a saturable reactor, and at a time point when the switching element is to be turned off, the analog input signal is converted into a pulse signal insulated from the analog input signal, and the pulse signal is outputted from another winding of the saturable reactor. By such a system, a switching power supply having a very simple circuit arrangement and high output voltage precision can be achieved.

Abstract: A compact multiple output switching power supply having a series connection of a D.C. input power supply, a switching device and a primary winding of a transformer which supplies currents to loads during an on period of the switching device, and supplies constant output voltages V.sub.i (i=1, 2, . . . , m) from m (m.gtoreq.2) secondary windings n.sub.i (i=1,2, . . . , m) of the transformer by turning on and off the switching device, includes means for storing a magnetic energy during the on period of the switching device and discharging the stored energy to the loads during on off period, connected in series with the primary winding of the transformer. The output voltage V.sub.j (j=2, 3, . . . , m) is represented byV.sub.j =(n.sub.j /n.sub.1).multidot.(V.sub.1 +k.sub.1)-k.sub.jwhere k.sub.j is a voltage drop in the circuit.

Abstract: A magnetically controlled switching regulator which controls an output voltage using a saturable reactor, wherein the saturable reactor is constituted by a first winding through which an output current flows and a second winding through which a reset current flows. The energy for resetting the saturable reactor is supplied from a capacitor in a smoothing circuit for an output voltage. A turn ratio between the first and second windings is set so that a sufficiently high reset voltage is obtained. Since the reset current of the saturable reactor does not flow through a transformer, the saturation of the transformer and a high increase in temperature thereof do not occur, so that the core of the transformer can be miniaturized and a high gain of the output voltage control circuit can be derived.

Abstract: In accordance with the present invention, there is provided a power supply apparatus comprising a primary winding of a main transformer and a semiconductor device with a control electrode connected in series between both electrodes of a DC power source, a drive current being fed to said control electrode of said semiconductor device via an auxiliary transformer, and output being obtained on a secondary winding of said main transformer by turning on and off of said semiconductor device, wherein a tertiary winding is provided on said main transformer and a negative polarity drive current is flowed into said semiconductor device via said tertiary winding when said semiconductor device is to turn off.