Abstract: A switching transistor is connected to a primary winding of a transformer, an oscillation frequency control circuit is connected to a feedback winding, the oscillation frequency control circuit controls a first controlling transistor, and the first controlling transistor controls the delay time when the switching transistor is turned on. The oscillation frequency control circuit is set in a first operation mode in which the above delay does not take place at the rated load, in a second operation mode in which the oscillation frequency is controlled such that the oscillation frequency becomes constant or slowly decreases at light loading and in a third operation mode in which the oscillation frequency is further decreased while a switch is switched on.

Abstract: An intermittent switching power supply circuit prevents excessive output power on a secondary side of a circuit. An intermittent oscillator is alternately switched on and off to maintain output voltage and/or current roughly constant. An output power monitoring circuit monitors output power from a rectifying/smoothing circuit. A control circuit outputs a stop control signal to an control terminal of the intermittent oscillator when the output power monitoring circuit determines that the output voltage and/or current exceeds a reference value. The protection circuit and a photocoupler receiver element are connected in parallel with the control circuit. Where a circuit error occurs and the photocoupler receiver element fails to cycle the intermittent oscillator between active and inactive conditions for a predetermined time, the protection circuit provides a backup which outputs a stop control signal to stop oscillation of the intermittent oscillator element.

Abstract: A DC/DC converter is provided that includes a switch device for converting a DC voltage into an AC voltage, a piezoelectric transformer for changing the AC voltage and a current doubler type rectification-smoothing device, which includes a first diode, a second diode, a first inductor, a second inductor, and a capacitor. The piezoelectric transformer has one output terminal connected to a cathode of the first diode and to one terminal of the first inductor, and the other output terminal connected to a cathode of the second diode and to one terminal of the second inductor. Anodes of the first and the second diodes are respectively grounded. The other terminal of the first inductor is connected at a predetermined connection point to the other terminal of the second inductor. The connection point is connected to one terminal of the capacitor, whose other terminal is grounded.

Abstract: In a configuration which is provided with a voltage control circuit 2 for supplying a DC voltage control signal created on the basis of the voltage detecting signal 44 to an terminal of an auxiliary coil L3, wherein the voltage control circuit 2 controls the oscillating amplitude of a transistor Q1 for oscillation using the voltage control signal to stabilize the voltage of the secondary output, and the secondary output is led to a high voltage applying portion of a toner system printing section, a detecting signal creating circuit 5 rectifies the output from the voltage detecting coil L4 at the same timing as the rectifying/smoothing circuit rectifies the output from the secondary coil L2.

Abstract: The present invention provides a ring choke converter, a kind of power supply, and method thereof. In addition to the transformer, the switch component, the positive feedback circuit and the regulation control circuit in a conventional RCC, the present invention provides a control circuit partially powered by terminal of the opposite polarity at the feedback winding of the transformer. With the circuit design of the control circuits disclosed in this invention, under-voltage protection (UVP), over-voltage protection, and overload protection, together with stable output voltage are all achieved.

Abstract: When a main switching transistor of a zero voltage switching power supply is conductive, a voltage is developed in a current sensing resistor coupled in series with the transistor. The voltage in the current sensing resistor is coupled to a control terminal of a comparator transistor. During a given conduction interval of the main switching transistor, the comparator transistor is turned on when the current sensing resistor voltage is sufficiently large to turn on the comparator transistor. An output of the comparator transistor is coupled to the control terminal of the main switching transistor for controlling the turn off instant of the main switching transistor on a current pulse-by-current pulse basis. A resonant voltage pulse developed at a main current conducting terminal of the main switching transistor is capacitively coupled to the control terminal of the comparator transistor for maintaining the comparator transistor turned on, during a transition interval of the resonant voltage pulse.

Abstract: This invention provides a method and apparatus for magnetic amplifier to reduce the minimum load requirement of power supply. The apparatus comprises a voltage-dropper and a current-limiter. Through the voltage-dropper and the current-limiter, the master output of the power supply is coupled to the output of magnetic amplifier. The differential voltage of the master output and the magnetic amplifier output decide the voltage of the voltage-dropper. The current-limiter limits the current flows from the master output to magnetic amplifier output. If the master output is no load and the magnetic amplifier is full load condition, a start-up current will flow from the master output to the output of magnetic amplifier via the voltage-dropper and the current-limiter. In the mean time, the start-up current will widen the pulse width of the PWM signal until the current-limiter limits the current. The maximum current of the current-limiter is assigned to maintain the minimum pulse width of the PWM signal.

Abstract: DC/DC conversion circuit (1), includes a transformer (2) having a primary winding (3), a secondary winding (4), and an auxiliary winding (5); a switching transistor (T), including a series circuit with the primary winding (3) between first and second direct current input terminals (6; 7); a start circuit (R1, C1) connected to a control electrode of the switching transistor (T) for switching the switching transistor (T) on by powering the direct current input terminals (6; 7); a control transistor connected to the control electrode of the switching transistor (T) for switching off the switching transistor (T) in dependence on a current flowing through the series circuit during operation.

Abstract: A push-pull inverter is supplied from an inductively current-limited DC voltage source by way of a center-tap on a transformer having significant inductance. This transformer inductance is parallel-coupled with a capacitance means. The inverter is made to self-oscillate through positive feedback provided by way of a saturable current transformer. The inverter frequency is determined by the saturation time of this current transformer, which saturation time is designed to be somewhat longer than the half-cycle period of the natural resonance frequency of the transformer inductance combined with the capacitance means. By controlling the length of this saturation time, the magnitude of the current provided to the fluorescent lamp is controlled, thereby permitting control of the light output in response to changes in the magnitude of the power line voltage.

Abstract: In an insulating converter transformer of a composite resonance type switching power supply circuit having a secondary active clamp circuit, a primary winding and a secondary winding are wound in a so-called inverse winding style, and connected to each other with additive polarity. In this construction, a primary magnetic flux and a secondary magnetic flux act to offset each other, so that no saturation occurs without forming any gap in the core of the insulating converter transformer.

Abstract: A switching power supply apparatus comprises a transformer having primary winding and at least two secondary windings, a first switching element connected in series with the primary winding, a control circuit for controlling the output from the first switching element by control of the on-time thereof, a rectification circuit for rectifying at least two outputs from the secondary windings, an output detection circuit for detecting the output voltages and feeding back the output voltages as a control signal for control of the on-time to the control circuit. The output voltage detection circuit comprises a control signal formation section in which the control signal for the on-time is formed, corresponding to a voltage at a voltage comparison terminal, and plural voltage detectors connected between the at least two outputs of the secondary windings and the voltage comparison terminal, respectively.

Abstract: A switching power supply unit includes first and second switching circuits which alternately turn first and second switching elements on and off with an intermediate period in which both are turned off, and energy is stored in a primary winding of a transformer during an ON period of the first switching element and the energy is discharged from a secondary winding of the transformer during an OFF period of the first switching element. A control circuit includes an OFF period extending circuit connected to a control terminal of the first switching element, such that a transistor remains turned on for a desired period even after the energy has been discharged from the secondary winding, extending the OFF period of the first switching element for the desired period. In a light load operation, a phototransistor in the second control circuit is turned on so that the ON period of the second switching element will be shorter than the time required to discharge the energy from the secondary winding.

Abstract: A power converter individually comprises a first semiconductor device <2> and a second semiconductor device <3>. In the first semiconductor device <2>, a power conversion element such as an IGBT <19>, Zener diodes <20, 21>, a waveform shaping circuit <30>, a heating cutoff circuit <31> and a protective element <14> are formed on the same chip employing a p-type silicon substrate. In the second semiconductor device <3>, a Schmidt circuit <9>, a power supply circuit <10>, a high voltage detection circuit <11>, a protective element <13>, a logic gate <16> and an output circuit formed by a pnp transistor <17> are formed on the same chip employing a p-type silicon substrate. Thus, a power converter capable of reducing the circuit scale as a whole is obtained.

Abstract: The invention provides a switching power circuit and an insulating converter transformer. A tertiary winding to be formed on the secondary side of an insulating converter transformer is coiled in such a manner as to achieve a state of tight coupling with respect to a primary winding on the primary side of the insulating converter transformer and also to a secondary winding on the secondary side thereof, so that the peak value of a secondary current outputted from a second half-wave rectifying circuit can be reduced by the tertiary winding of the insulating converter transformer.

Abstract: A self-oscillation type resonant flyback converter includes a series combination of a primary winding and a switching transistor. A secondary winding is connected to a power diode and to an output capacitor. A feedback winding is connected to a delay driving circuit comprising a delay diode, a constant-current diode and a capacitor. The delay driving circuit is provided to delay a positive feedback signal from said feedback winding, so that when said power diode becomes non-conducting, said delay diode becomes in the reverse conduction state, starting a free resonance period that concludes when the said delay diode becomes non-conducting and the switching transistor is achieved at zero voltage switching.

Abstract: A power converter individually comprises a first semiconductor device <2> and a second semiconductor device <3>. In the first semiconductor device <2>, a power conversion element such as an IGBT <19>, Zener diodes <20, 21>, a waveform shaping circuit <30>, a heating cutoff circuit <31> and a protective element <14> are formed on the same chip employing a p-type silicon substrate. In the second semiconductor device <3>, a Schmidt circuit <9>, a power supply circuit <10>, a high voltage detection circuit <11>, a protective element <13>, a logic gate <16>and an output circuit formed by a pnp transistor <17>are formed on the same chip employing a p-type silicon substrate. Thus, a power converter capable of reducing the circuit scale as a whole is obtained.

Abstract: A switching power supply apparatus comprises a transformer having primary winding and at least two secondary windings, a first switching element connected in series with the primary winding, a control circuit for controlling the output from the first switching element by control of the on-time thereof, a rectification circuit for rectifying at least two outputs from the secondary windings, an output detection circuit for detecting the output voltages and feeding back the output voltages as a control signal for control of the on-time to the control circuit. The output voltage detection circuit comprises a control signal formation section in which the control signal for the on-time is formed, corresponding to a voltage at a voltage comparison terminal, and plural voltage detectors connected between the at least two outputs of the secondary windings and the voltage comparison terminal, respectively.

Abstract: Instead of inputting a horizontal deflection output pulse, a resonance voltage outputted from the secondary side of an isolation converter transformer forming a switching power supply circuit of the complex resonance type is inputted to the primary side of a flyback transformer via a series resonant capacitor. Then, a resonance voltage having a substantially sinusoidal waveform generated in the primary winding of the flyback transformer is stepped up thereby providing a high direct-current voltage having a specified high voltage level. Thus, it is possible to improve power conversion efficiency and reduce power loss. Also, by inducing a resonance voltage having a substantially sinusoidal waveform on the secondary side of the flyback transformer, the conduction angle of a rectifier diode is widened, and variation in the high direct-current voltage can be surpressed even when the load is varied.

Abstract: A voltage from an AC power source is converted into a DC voltage in an input-side rectifier-smoother circuit. The DC voltage is then converted into a high-frequency voltage in an inverter, and the resulting high-frequency voltage is voltage-transformed in a transformer. The voltage-transformed high-frequency voltage is converted into a DC voltage in an output-side rectifier-smoother circuit, which is applied via output terminals to a load. The input-side and output-side rectifier-smoother circuits, the inverter and the transformer are enclosed in a casing having a plastic panel. The output terminal of the apparatus is mounted on the plastic panel.

Abstract: Transformer driving coils 24 and 25 are added to a DC-DC converter composed of a DC power supply 1, semiconductor switching devices 91 and 92, a transformer 2, rectifiers 81 and 82, a filter capacitor 3, and others, in order to perform a self-oscillating operation. On the other hand, an output-voltage detection and control circuit 6 is used to provide control consisting of both frequency and pulse-width modulation, thus keeping the output voltage constant without the use of any expensive IC circuits or pulse transformers.

Abstract: A multimode switched-mode power supply operates in a first control mode when the output power supplied is lower than a predetermined value, and in a second control mode when the output power supplied is higher than said predetermined value. The switched-mode power supply comprises a series arrangement of a switch (S1) and an inductor (L; Lp), the series arrangement being coupled to receive a DC input voltage (Vin). A control circuit (CC) controls the on and/or off times of the switch (S1) to generate a periodical inductor current (Ip) in the inductor (L; Lp). In the first control mode, a peak value of the inductor current (Ip) is substantially constant, independent of the power supplied. The substantially constant peak value is substantially equal to a peak value of the inductor current (Ip) at an instant when the second control mode is altered into the first control mode.

Abstract: A DC/DC up/down converter (10), comprising first and second input terminals (20, 21); first and second output terminal (30, 31); a coil (L); first switching means (S1) operatively connected to provide a conduction path from said first input terminal (20) to said coil (L) second switching means (S2) operatively connected to provide a conduction path from said first switching means (S1) and said coil (L) to said second input terminal (21); third switching means (S3) operatively connected to provide a conduction path from said coil (L) to said first output terminal (30); fourth switching means (S4) operatively connected to provide a conduction path from said coil (L) and said third switching means (S3) to said second output terminal (31); control means (11) operatively connected for controlling said switching means (S1, S2, S3, S4); reference voltage means (12) for providing a reference voltage (Vr); and comparator means (13) for providing a comparison signal (Vc) for said control means (11) in response to compa

Abstract: A switching power supply circuit has an insulated converter transformer with a gap for a loose coupling. on the secondary side, a parallel resonant capacitor is connected parallel to a secondary winding, and a full-wave rectification circuit produces a secondary-side DC output voltage for increasing a maximum load power. On the primary side, an ordinary full-wave rectification circuit, rather than a voltage doubler rectifying circuit, inputs a rectified and smoothed voltage having a level corresponding to the level of an AC input voltage. A constant-voltage control circuit system for stabilizing a secondary output voltage varies a switching frequency depending on the level of the secondary output voltage to perform composite control over a resonant impedance of a primary parallel resonant circuit and a conduction angle of the switching element.

Abstract: A switching power source in which the voltage error of a secondary side DC output is fed back to a switching circuit through an insulating element, thereby to stabilize the output voltage. In the switching power source, irrespective of the voltage of the secondary side DC output, a pulse of the level with which an error detecting circuit determines that the voltage of the secondary side DC output has been increased is applied to the error detecting circuit, whereby the switching operation of the switching circuit is changed into an intermittent operation corresponding to the pulse.

Abstract: A switching power supply unit includes a DC power supply, a transformer having a primary winding, a secondary winding and a feedback winding, a main switching element connected in series to the primary winding, and a control circuit connected between the feedback winding and the control terminal of the main switching element, so that a DC output can be obtained. In this switching power supply unit, there are provided a voltage generating unit disposed on the primary side of the transformer to output a voltage according to a load power, and a delay circuit for reducing the switching frequency by delaying the turn-on of the main switching element according to a voltage output from the voltage generating unit thereby to prolong the OFF time of the main switching element.

Abstract: A power supply system includes an a-c. power source and an off-line power supply for storing energy from the a-c. power source during first selected time intervals and converting at least a portion of the stored energy to a d-c. output during second selected time intervals. A diode or other switch disconnects the off-line power supply from the a-c. power source during the second selected time intervals to reduce conducted EMI. The first and second selected time intervals are preferably synchronized to the frequency of the a-c. power source.

Abstract: DC/DC conversion circuit (1), comprising a transformer (2) having a primary winding (3), a secondary winding (4), and an auxiliary winding (5); a switching transistor (T), comprising a series circuit with the primary winding (3) between first and second direct current input terminals (6; 7); a start circuit (R1, C1) connected to a control electrode of the switching transistor (T) for switching the switching transistor (T) on by powering the direct current input terminals (6; 7); a control transistor connected to the control electrode of the switching transistor (T) for switching off the switching transistor (T) in dependence on a current flowing through the series circuit during operation.

Abstract: A switching power supply uses zero-current and zero-voltage switching to reduce switching noise. A main switch and an auxiliary switch channel current and voltage between various component paths to maintain a DC output voltage while switching at zero-current or zero-voltage states. Switch ON-OFF time ratios are controlled with a simple scheme to improve the circuit power factor. The switching rate is set to arbitrary frequencies, with switch ON time and OFF time being controlled independently. Conventional losses in efficiency when driving a load substantially less than the rated load are avoided. The switches and control functions can be implemented on an integrated circuit, reducing size and improving efficiency. Thus a flexible, simple design improves efficiency while reducing noise and manufacturing costs.

Abstract: A self-oscillation switching power supply apparatus of the ringing choke converter type comprises a transformer T including a primary winding N1, a secondary winding N2, and a feedback winding NB; a switching transistor Q1 which oscillates in a self-oscillating fashion in response to a feedback signal from the feedback winding NB thereby turning on and off the current flowing through the primary winding; a rectifying and smoothing circuit connected to the secondary winding; an oscillation frequency control circuit including a control transistor Q3 for controlling a control signal input to the switching transistor Q1 thereby controlling the control transistor Q3 so as to extend the off-time in the self-oscillation period of the switching transistor Q1; and an oscillation frequency control disabling circuit for disabling the control of the control transistor Q3 in accordance with a remote signal.

Abstract: The present invention relates to a switching power-supply circuit comprising: rectifying and smoothing means for generating a rectified and smoothed voltage and outputting the rectified and smoothed voltage as a direct-current input voltage; an insulating converter transformer for transferring a primary-side output to a secondary side; switching means for intermittently passing on the direct-current input voltage to a primary winding of the insulating converter transformer; a primary-side resonance circuit for actuating the switching means in a voltage resonance mode; power-factor improvement means for improving a power factor by generating intermittently a rectified current based on the fed-back switching output voltage; a secondary-side resonance circuit on a secondary side of the insulating converter transformer; direct-current output voltage generation means carrying out a rectification operation in order to generate a secondary-side direct-current output voltage; and constant-voltage control means for ex

Abstract: A switching power supply having two or more DC outputs comprising: a DC power supply, a transformer having a primary winding, at least two secondary windings, and a feedback winding, a main switching element having an off-state period and an on-state period, connected in series to the primary winding and to be turned on by a voltage generated in the feedback winding, the main switching element having a control terminal and a threshold voltage to turn the main switching element on; and a rectifying circuit connected to each secondary winding, a starting circuit which initially turns on the main switching element at startup of the power supply and a switching circuit provided between the two DC outputs, and wherein, when the switching circuit is turned on, a voltage generated in the feedback winding is lowered during the off-state period of the main switching element and a voltage to be applied to the control terminal of the main switching element is controlled so as to be less than the threshold voltage, and t

Abstract: A power circuit for use in a TV receiver having a satellite broadcast receiving function or a teletext receiving function is disclosed. The power circuit comprises a main power source for supplying a large power to the main load, i.e., the signal-reception, signal-processing, and display circuits of the TV receiver, and a sub-power source for supplying power to small-power drawing circuits such as a satellite broadcast receiving tuner, a UHF/VHF tuner, a teletext receiving circuit, a microprocessor, and a remote control receiving circuit. In order to activate the main load while power is being supplied from the sub-power source to the sub-load, a switch circuit is turned ON and, thereby, the main power source is supplied to the main load.

Abstract: The protection circuit comprises a storage capacitor which is coupled with a terminal of a secondary winding which charges said storage capacitor during the on-interval of the switching transistor. During the off-interval of the switching transistor the charge of the storage capacitor is fed to the driver stage or the control capacitor for closing or keeping closed the switching transistor when one of the secondary windings has a short circuit.

Abstract: An apparatus for supplying a DC voltage to a load which can be connected to output terminals. The apparatus has a semiconductor switching element for a clocked application of a supply voltage to a primary of a transformer on the basis of a sequence of driving pulses applied to a control input of the semiconductor switching element. A driving circuit is provided for producing driving pulses. The driving circuit has a first input terminal for receiving an analog load-dependent control signal which is produced by a measuring configuration and governs a duration of the individual driving pulses. The driving circuit also has a second input terminal for receiving a starting signal defining turn-on instants of the driving pulses. The apparatus further has a pulse generator with an output terminal, connected to the input terminal of the driving circuit, for providing the pulsed starting signal on the basis of a control signal.

Abstract: A switching power supply device in which the increase in the switching frequency when the load is light is restrained, whereby the switching loss is reduced, intermittent oscillating operation is prevented, and heat generation in the main switching device at the time of short-circuiting is restrained. In a switching power supply device, the charging/discharging time of a capacitor of a switch circuit comprising a time-constant circuit is controlled so as to make the OFF-period of a main switching element a predetermined period that continues after the completion of the discharge of excitation energy from the secondary coil of a transformer of the power supply device.

Abstract: A circuit for detecting whether or not an AC voltage mains is providing an AC voltage above a predetermined point including a full wave bridge and voltage divider, a voltage detection circuit including a pair of transistors and a zener diode, an optical coupler including a light emitting diode (LED) and photo transistor, a comparator circuit for determining whether or not the AC voltage source has been below a predetermined voltage for a predetermined length of time including a comparator circuit such as a comparator or a FET.

Abstract: A switching power supply unit providing a DC output has a DC power supply; a transformer having a primary winding and a secondary winding; a main-switching element for connecting in series to the primary winding; one or more sub-switching elements for performing ON/OFF operations in synchronism with or opposite to the ON/OFF operations of the main-switching element; a sub-switching-element drive winding disposed in the transformer for generating voltage turning the sub-switching element on; a turn-off switching element for turning the sub-switching element off; and a time-constant circuit for controlling the turn-off switching element.

Abstract: A switching power supply circuit includes a transformer having a primary winding, a secondary winding, and a feedback winding, a switching element connected in series to a first of the primary winding, a control circuit disposed between a control terminal of the switching element and the feedback winding, a starting circuit connected between a second end of the primary winding and the control terminal of the switching element, and a rectifying/smoothing circuit connected to the secondary winding.

Abstract: A solid state power supply circuit for providing high frequency power to ignite oil or gas and operate neon sign transformers. A switch operates in conjunction with a resonant tank circuit to supply power to the resonant tank at a predetermined time. The timing of the pulse is controlled to occur when the operation of the transistor will result in providing maximum energy to the load while minimizing power dissipation in the transistor. An amplifier and clamping circuit also operate to limit the duration of the pulse to further reduce power dissipation in the switch.

Abstract: A switching power supply device comprises: a transformer having a primary winding, a secondary winding and a feedback winding; a switching element connected in series with the primary winding; a controlling element connected to a control terminal of the switching element; a controlling circuit provided between the controlling element and the feedback winding; a rectifying circuit connected to the secondary winding; and a frequency limiting circuit including a charging circuit and a kick voltage absorbing circuit. The charging circuit is adapted to be charged by a voltage reverse in polarity, produced in the feedback winding. The kick voltage absorbing circuit absorbs a current developed by a kick voltage in the feedback winding, by discharge of the charging circuit, whereby the frequency limiting circuit reducing the switching frequency of the switching element by prolongation of the off-state time-period of the switching element in correspondence to a light load signal from a load when the load is light.

Abstract: A transformer and switching regulator that prevents winding's breakdown caused by the leakage magnetic field. A transformer has a core having an air gap, and a winding wound around the core. The turn density of the winding is made least on the air gap. The switching regulator has such a transformer.

Abstract: In a switching power source of the RCC system in which excited energy, accumulated in a transformer during an on-period of a main switching element, is outputted to the secondary side during an off-period, and a ringing pulse, which appears in a control coil of the transformer upon completion of the output, is fed back to the gate of the main switching element through a capacitor used for cutting a dc so that the main switching element is on-driven, a bias resistor is interpolated between the capacitor and the gate, and during the stand-by state, a control transistor is turned on, with the connecting point between them being connected to a main power-source line in a low level through a series circuit consisting of a diode, Zener diode and a resistor. Thus, a higher charge is allowed to accumulate in the capacitor, and the ringing pulse is reversely biased by the charge so as not to cause the re-starting.

Abstract: The switched-mode power supply comprises a secondary winding and four diodes for producing two rectified voltages of the same polarity, one of which can be regulated. A connection of the unregulated voltage has connected to it a variable Zener diode as an error amplifier for transmitting a regulating signal to the primary side. The driver stage provides a pulse-width-modulated square-wave signal for driving the switching transistor which is arranged at a high potential between the operating voltage on the input side and a first connection of the primary winding. The second connection of the primary winding is connected with a Zener diode and provides a stabilized voltage for the driver stage. Arranged between the driver stage and the control electrode of the switching transistor there is a differentiating element which produces positive and negative switching voltages for controlling the switching transistor.

Abstract: A switching power supply unit containing a DC power supply; a transformer having a primary winding, a secondary winding and a feedback winding, a main switching element connected in series to the primary winding to be turned on by a voltage generated at the feedback winding, and a voltage dropping circuit for dropping the output voltage obtained form the secondary winding to reduce a fly-back voltage so that the voltage of a control terminal of the main switching element is maintained at a lower value than a threshold voltage of the main switching element.

Abstract: A self-excited DC-DC converter and a power supply device using the same which can produce a constant output voltage for a wide range of input voltage without using high voltage components.

Abstract: A self-oscillation type switching power supply apparatus comprises a transformer T having a primary winding N1, a secondary winding N2, and a feedback winding N.sub.B, a switching transistor Q1 to interrupt current in the primary winding supplied with an input power supply voltage, a feedback signal being provided from the feedback winding N.sub.B and a rectifying smoothing circuit connected to the secondary winding. The self-oscillation type switching power supply apparatus further comprises a controlling transistor Q3 to control a positive feedback signal for the switching transistor Q1 from the feedback winding N.sub.B, and a detector detecting a flyback voltage produced in the feedback winding N.sub.B when the switching transistor Q1 is turned off, and changing-over the state of the controlling transistor Q3 to keep the switching transistor Q1 in the off-state when the flyback voltage goes lower than a predetermined value.

Abstract: A circuit for providing a D.C. voltage of high value from the output of a rectifying bridge on a capacitor of high capacitance, and for providing low supply voltages, including a first diode connected between the output of the rectifying bridge and the capacitor, first and second cascode-mounted transistors, circuitry for setting the potential of the control terminal of the first transistor, circuitry for reducing the potential of this control terminal when the rectified voltage exceeds a predetermined value, a regulation circuit connected at the connection node of the first and second transistors, and circuitry for applying, to the second transistor, a turn-on pulse of determined duration after the output voltage of the bridge has exceeded the determined value.

Abstract: A synchronous rectifier is disclosed which makes use of current driving technique to enable low conduction loss in converter rectifiers. In addition to a low loss switch the present invention comprises essentially a transformer with a plurality of windings with at least one current sensing winding, one driver winding which provides driving signal for the synchronous rectifier, and windings for energy recovery. This synchronous rectifier is self-driven but operates independent of converter input voltage hence allow wide input voltage range. It also avoids effect of leakage inductance in converter transformer windings. With energy recovery means it can operate with high efficiency. This synchronous rectifier can operate in many different circuit topologies.

Abstract: A non-contact electrical power transmission system is capable of providing a large supply current of uniform level at an optimum transmission efficiency. The system includes a power circuit including a power supply of providing a high frequency voltage across a power winding, and a load circuit for energizing a load. The load circuit is composed of a secondary winding, a matching capacitor, a rectifier, and a choke coil. The secondary winding is magnetically coupled to the power winding so as to generate an induced high frequency voltage and to provide a leakage inductance to the load circuit. The matching capacitor is connected across the secondary winding to be cooperative with the leakage inductance and with the secondary winding to form an oscillatory circuit which provides an oscillating voltage across the matching capacitor for generating a supply current being fed through the rectifier and the choke coil to the load.

Abstract: Regulation of the output voltage of a power supply employing a flyback-type self-oscillating DC—DC converter employing a transformer. The primary winding circuit of the transformer senses a current recirculation loop for discharging the energy cyclically stored in an auxiliary winding of the self-oscillation loop of the converter such as to represent a replica of the circuit of the secondary winding of the transformer and by summing a signal representative of the level of the energy stored in the auxiliary winding with a drive signal on a control node of a driver of the power switch of the converter.