Abstract: This application discloses a converter and a power adapter, to reduce an energy loss of the power adapter. The converter includes: a DC power supply, a primary power transistor, an auxiliary power transistor, a first capacitor, a transformer, and a control circuit. The first capacitor is connected in series to the transformer to form a series circuit, the series circuit is connected in parallel to a first terminal and a second terminal of the auxiliary power transistor. The control circuit is configured to: when an excitation current in the transformer is in a continuous state, regulate a target voltage to a preset voltage threshold, and control the primary power transistor to be turned on when first dead time ends, where the target voltage is a voltage between the first terminal of the primary power transistor and the ground.

Abstract: The invention relates to the galvanically isolated transmission of electrical power between three voltage systems. For this purpose, a transformer is provided which comprises a total of five windings. The transmission between the individual voltage systems can be controlled by targeted manner activation of the individual windings.

Abstract: Disclosed is a driver IC circuit of an intelligent power module including an upper bridge control signal input end, a lower bridge control signal input end, a PFC control signal input end, a logic input buffer circuit, a first upper bridge driver circuit, a second upper bridge driver circuit, a first lower bridge driver circuit, a second lower bridge driver circuit and a PFC driver circuit. The logic input buffer circuit performs full-wave filtering on control signals. The first upper bridge driver circuit, the first lower bridge driver circuit, the second upper bridge driver circuit and the second lower bridge driver circuit each drives a switch transistor corresponding to a first or second external motor according to one of the control signals. The PFC driver circuit drives an external PFC switch transistor according to one of the control signals. An intelligent power module and an air conditioner are also disclosed.

Abstract: An isolated, power factor corrected, converter, for operation from a three-phase AC source, comprises three power processors, each power processor connected to one of the three phases. Each power processor comprises a cascade of a first and a second power conversion stage. At least one of the first and second power converters in each power processor is configured to provide galvanic isolation through a DC Transformer between the power processor input and output. At least one of the first and second power converters in each power processor is configured to provide power factor correction at the AC source. Substantially all of the bulk energy storage and low frequency filtering is provided by storage elements at the output of the power system. Low voltage semiconductor devices may be cascaded to implement low output capacitance high voltage switches in a multi-cell resonant converter for high voltage applications.

Abstract: An arrangement includes a conductor, forming the primary side of a transformer, the secondary side being connected to a rectifier circuit. The rectifier output is connected to a voltage stabilizing circuit for an electronic unit and to a first series circuit formed by a first switching component and a first resistor. In the event of a first voltage value being reached at the first input of the voltage stabilizing circuit, the first switching component is switched to be conductive. The secondary current of the transformer flows via the first resistor to drop an electrical voltage across the first resistor. The electric current of conductor is determinable from the voltage. The use of just one transformer used both for energy generation and for current measurement makes it possible to realize a very compact and small design of a current measuring device having a simple construction.

Abstract: A voltage detection circuit includes an inductor connected to connection portions configured to input an alternating-current voltage, an inductor magnetic-field coupled to the inductor, a capacitor connected in parallel to the inductor and constituting a secondary-side resonant circuit with the inductor, and a voltage detector configured to detect an output voltage from the secondary-side resonant circuit. Therefore, a voltage detection circuit, a power transmission device, and a power transmission system capable of detecting an alternating-current voltage with high detection sensitivity irrespective of the potential of a power transmission line are provided.

Abstract: A method, apparatus, and system are provided which enables the control of contactless power transfer in an inductive power transfer system using a phase control technique. The method comprises adjusting the phase of a secondary-side converter output voltage with respect to that of a primary-side converter. The magnitude of power transfer is determined by the relative phase angle, and the direction of power transfer is determined by whether the secondary converter output voltage leads or lags the input converter voltage, thereby enabling bi-directional power transfer between the primary and secondary sides of the system. According to alternative embodiments, the method may also be used for uni-directional power transfer only, and/or the secondary converter may be operated to maintain a constant relative phase angle.

Abstract: A charger, in one possible configuration, has an AC/DC converter that converts alternating current power supplied from an external alternating current power supply into direct current power and outputs the direct current power, a DC/DC converter that transforms the direct current power output by the AC/DC converter and supplies the transformed direct current power to a vehicle-mounted battery, and a safety control unit that forcibly stops the DC/DC converter with detection of an occurrence of a fault during charging of the vehicle-mounted battery as a trigger, and subsequently causes the AC/DC converter to stop normally.

Abstract: Various techniques are disclosed for providing electrical power and/or data from the interior of a building structure to a device at the exterior of the structure without piercing (e.g., making a hole through a wall or window frame) the structure. A camera surveillance system for an embodiment includes self-adhesive energy transfer units that can be placed on either side of a window so that electrical power is passed via the energy transfer units from inside a building to the outside without the need for making a hole in the window or building through which to pass electrical wire to feed power and/or data to/from the camera surveillance system. One of the energy transfer units may be integral with the camera surveillance system and the adhesive may be strong enough to support the weight of the camera surveillance system on the window. The camera surveillance system may be installed without the need for tools.

Abstract: A non-contact power transmitting and receiving system includes an inverter configured to generate a high-frequency voltage, a voltage-current sensor configured to detect a phase difference between an output voltage and an output current of the inverter, a power transmission coil connected to the inverter, a power reception coil configured to receive electric power from the power transmission coil in a contactless manner, a rectifier circuit connected to the power reception coil, and a control unit configured to control the inverter and the rectifier circuit. The inverter includes arms. The rectifier circuit includes arms. The control unit adjusts at least one of switching timing of any arm of the inverter and switching timing of any arm of the rectifier circuit, in accordance with the phase difference detected by the voltage-current sensor.

Abstract: A self-excited push-pull converter, which comprises a Royer circuit, wherein an inductor is further connected between a supply terminal of said Royer circuit and a center tap of primary windings of a transformer in said Royer circuit, an inductance amount of said inductor is less than 1/10 of the inductance amount of one of the primary windings of the transformer, and the center tap of said primary windings is a connection point between the two primary windings of said transformer. The self-excited push-pull converter of the present invention show high consistency, easy adjustment, low requirements on the manufacturing process and good short circuit protection performance.

Abstract: A self-excited push-pull converter, comprising a Jensen circuit, characterized in that a two-terminal network with an electrical property of passing high frequencies and blocking low frequencies exists between a terminal of a magnetic saturation transformer primary winding and a terminal of a main transformer primary winding in said Jensen circuit, i.e. said magnetic saturation transformer primary winding is connected in parallel with said main transformer primary winding through said two-terminal network. The self-excited push-pull converter of the present invention has a good self-protection capability and can be restored by itself to normal operation after overcurrent and short circuit disappear.

Abstract: A switching power source apparatus has a pulse generator of a first pulse. A first resonant series circuit receives the first pulse signal and passes a current having a 90-degree phase delay with respect to the first pulse signal. The current of the first resonant series circuit turns on/off a switching element Q21. A second resonant series circuit receives the second pulse signal and passes a current having a 90-degree phase delay with respect to the second pulse signal. The current of the second resonant series circuit turns on/off a switching element Q22. The pulse generator has a third transformer T3 that has secondary windings to output the first and second pulse signals according to a voltage that is applied to the third transformer and is synchronized with drive signals for the switching elements Q11 and Q12.

Abstract: A switching power supply apparatus includes a low-side switching control unit and a high-side switching control unit. The low-side switching control unit includes a low-side turn-off circuit that turns off a low-side switching element behind a delay time when reversal of the polarity of a winding voltage of a transformer is detected during a period in which a drive voltage signal is supplied to the low-side switching element. The high-side switching control unit includes a high-side turn-on delay circuit that delays a time from the time when the polarity of the winding voltage of the transformer is reversed to a time when a high-side switching element is turned on. The delay time of the low-side turn-off delay circuit is set so as to be shorter than the delay time of the high-side turn-on delay circuit.

Abstract: A switching control IC conducts on-off control on a first switching element. A second switching control circuit is provided between a high-side driving winding of a transformer T and a second switching element. The second switching control circuit discharges a capacitor in a negative direction with a constant current during an on period of the first switching element, and then after the second switching element is turned on, charges the capacitor in a positive direction with a constant current. A transistor controls the on period of the second switching element in accordance with the ratio of a charging current to a discharge current such that the ratio of the on period of the second switching element to the on period of the first switching element is substantially always constant.

Abstract: A method for operating the DC-to-DC voltage regulator including plural active switches and plural inductors is disclosed. The method including the steps of: turning on the first active switch, and then turning off the first active switch when the current flowing in the first inductor is equal to zero; turning on the third active switch, and then turning off the third active switch when the current flowing in the second inductor is equal to zero; turning on the second active switch, and then turning off the second active switch when the current flowing in the first inductor is equal to zero; and turning on the fourth active switch, and then turning off the fourth active switch when the current flowing in the second inductor is equal to zero.

Abstract: A resonant inverter includes inductive elements (L1, L2) that allow the number of magnetic components in the inverter to be reduced. The elements (L1, L2) may be designed with a leakage inductance to eliminate the need for a large DC inductor. They may also perform the function of a current splitting transformer. The inverter switches may also be driven directly from the inverter circuit without a separate controller being required.

Abstract: A discharge lamp lighting apparatus includes a switch circuit for DC/AC converting, a discharge lamp connected to a secondary winding of a transformer, a current detector detecting an AC output current of the discharge lamp, an error amplifier outputting an error signal to a detected current, a control circuit generating control signals that turn on/off the switching elements in such a way as to control the AC output current at a predetermined value, and a time division signal generator generating a time division signal at the start of an ON/OFF operation of the switching elements, wherein the time division signal delays a change in a burst dimming signal or has a predetermined inclination on the burst dimming signal. The error amplifier changes the error signal according to the time division signal from the time division signal generator.

Abstract: A buck-boost PFC converter is provided and includes an inductor, first and second transistors, a first diode, and a control circuit. The inductor has a first terminal and a second terminal. The first transistor is coupled to a positive-power rail and the first terminal of the inductor. The second transistor is coupled to the second terminal of the inductor and a negative-power rail. The first diode is connected from the second terminal of the inductor to an output of the buck-boost PFC converter. The control circuit generates a first signal and a second signal coupled to control the first transistor and the second transistor respectively. The first signal is utilized to turn on the first transistor for conducting the positive-power rail to the inductor. The second signal is utilized to turn on the second transistor for conducting the inductor to the negative-power rail.

Abstract: A kind of fluorescent lamp driver power consists of a multi-switch converting circuit, a power transformer, a resonant inductor, a resonant capacitor, a step-up transformer and a rectifier. The primary winding of the power transformer connects with an AC output of multi-switch converting circuit. The resonant inductor and the resonant capacitor are connect to the secondary winding of the power transformer through the primary winding of the step-up transformer. The secondary winding of the power transformer connects with the rectifier. The secondary winding of the step-up transformer connects with the load output. This invention combines the fluorescent lamp driver power and the power supply of the control system, so that energy transformation occurs only once for the output from the Power Factor Correction Circuit to lamp.

Abstract: An air cooled switching unit for a motor drive includes a plurality electrical switches and a plurality of heat pipe assemblies. Each heat pipe assembly includes a thermally and electrically conductive evaporator, a condenser, and at least one heat pipe extending between the evaporator and condenser. Each of the switches is abutted with an evaporator of at least one of the heat pipe assemblies for conduction of both electrical power and heat between the switch and the evaporator. Each heat pipe assembly further includes an electrically conductive base abutted with the evaporator, and the air cooled switching unit further includes a plurality of power lugs each connected to a base of a respective one of the heat pipe assemblies for input or output of electrical power to the base and the evaporator plate abutted with the base. Each heat pipe assembly includes at least one evaporator defined by a metallic plate. The condenser of each heat pipe assembly includes a plurality of parallel spaced-apart cooling fins.

Abstract: A dual-switch forward power converter, and a method of operating the same, employs a self-coupled driver to achieve among other advantages higher efficiency, lower part count and component cost. In one aspect of the present invention, a power converter comprises a transformer and two switching transistors, and said transformer has two serially-connected primary windings with the first winding connected to a first switching transistor which is biased by a pulse controller, and the second winding couples the voltage across said first winding to bias the second switching transistor. In addition, the circuit on the primary side of said transformer further comprises means of dissipating magnetization current and the circuit on the secondary side comprises a rectifier and a low-pass filter.

Abstract: A half-bridge resonant converter includes: a primary winding; a secondary winding having a first and a second end and a central point; a first electronic switch; a second electronic switch; a first power-storage element; a second power-storage element; and a load having a first and a second end. Wherein, the first end of said the secondary winding serially connects with said the first electronic switch and the first power-storage element, and the second end of said the secondary winding serially connects with said the second electronic switch and the second power-storage element, and the first end of said the load connects simultaneously with said the first power-storage element and the second power-storage element, and the second end connects with the central point of the secondary winding.

Abstract: A push-pull type self-oscillating power converter uses a main power transformer connected to a current transformer in series in such a way that a secondary current flowing through secondary sides of the two transformers is feedback to the primary side of the current drive transformer to generate a drive current for driving two switches. The drive current is proportional to the secondary current in the secondary side of the main power transformer.

Abstract: The present invention discloses a secondary side-driven half-bridge power supply, which has a half-bridge transformer. A MOSFET unit is connected to the primary side of the half-bridge transformer, and an output rectifier/filter circuit connected to the secondary side of the half-bridge transformer. In the present invention, a PWM controller generates a control signal and sends the signal to a separating element. The control signal is used to drive the MOSFET unit, and the MOSFET unit then drives the half-bridge transformer. The output rectifier/filter circuit processes the signal output by the half-bridge transformer to provide voltages for external loads. The present invention can increase the power efficiency, raise the working frequency, and reduce the cost.

Abstract: An electronic device that can receive an AM radio broadcast signal and has a switching power supply circuit, wherein a switching frequency of the switching power supply circuit is detected and a reception frequency of the AM radio broadcast signal is detected, and when a frequency as an integral multiple of the switching frequency falls within a reception frequency range of the AM radio broadcast signal, a load is added to the switching power supply circuit, whereby the switching frequency is changed.

Abstract: A pulse signal drive circuit includes an energy storage device. A source of energy supplies a substantially constant flow of energy to the energy storage device. A switch circuit draws repetitive pulses of substantially constant energy from the energy storage device to generate corresponding pulse drive signals.

Abstract: A high conversion efficiency inverter circuit by providing the current-mode resonant type efficient in using a power source.

Abstract: A highly stable current-mode resonant inverter circuit operates by detecting resonance current in the secondary side circuit. The inverter circuit comprises a step-up transformer with a secondary winding connected to a secondary side circuit with a capacitive component. The leakage inductance and the secondary winding and the capacitive component compose a series resonant circuit. The inverter circuit is configured to detect a current flowing through the secondary winding or capacitive component in the secondary side circuit, and determine a switching timing in response to the detected current. The determined switching timing allows the inverter circuit to oscillate self-excitedly at a resonance frequency of the series resonant circuit.

Abstract: A method of preventing the Rdson of a III-V Nitride power switching circuit from varying over time. The method includes biasing the switch to a pre-bias voltage level just below turn ON when the switch is OFF, wherein traps are discharged when the switch is biased to the pre-bias voltage level just below turn ON and the varying of the Rdson over time due to traps is reduced. The method can be employed in DC-DC converter circuits having III-V Nitride control and synchronous switches connected at a switching node.

Abstract: A push-pull converter has a transformer provided with a primary winding and a secondary winding. A capacitive element is connected between the input terminals of the primary winding, and two switch elements are arranged between a respective input terminal of the primary winding through an inductor and a supply input of the converter. The current-input terminals of the switch elements are connected to one another, and the current-output terminals of the switch elements are each connected to the respective input terminals of the primary winding. The switch elements are made up of NPN bipolar transistors connected in common-collector configuration. The push-pull converter is particularly suited for driving a cold-cathode fluorescent lamp.

Abstract: A push-pull type self-oscillating power converter uses a main power transformer connected to a current transformer in series in such a way that a secondary current flowing through secondary sides of the two transformers is feedback to the primary side of the current drive transformer to generate a drive current for driving two switches. The drive current is proportional to the secondary current in the secondary side of the main power transformer.

Abstract: A resonant switching power system operates with two resonant frequencies. A first frequency depends on the secondary leakage inductance of an output transformer and capacitor. The first frequency varies with changes in the load because load changes alter the leakage inductance. A second resonant frequency depends on the gate source capacitance of two MOSFET power devices in the circuit and the leakage inductance of the circuit's driving transformer. Power is thereby supplied that is always in phase with the load so that switching in the power supply occurs when current is near zero. High thermal efficiency is thereby achieved.

Abstract: A technique performed by a transformer-coupled DC-DC converter is described for recovering energy, due to leakage inductance in the transformer. A main power supply, providing a power supply voltage to a Vin terminal, is intermittently coupled to the primary winding of the transformer by a switching transistor. When the switching transistor is turned off, creating a voltage spike in the primary winding due to leakage inductance, the spike is conducted by a forward biased diode and filtered by a capacitor. The voltage at the capacitor (Vc) is then applied as an input voltage to a small pulse width modulated (PWM) regulator. The output of the PWM regulator is coupled to the Vin terminal along with the main power supply. The PWM regulator regulates the input voltage Vc to be a predetermined amount above the power supply voltage. Since the voltage spike energy is used to create the input voltage for the PWM regulator, and the output of the PWM regulator is fed back into the Vin terminal, the energy is recovered.

Abstract: A step-up converter based on an integrated transformer, comprising a self-resonating oscillator circuit that has inductive elements constituted by primary and secondary windings of at least one first transformer, the self-resonating oscillator circuit being powered by an external supply voltage.

Abstract: The invention discloses a half-bridge LLC resonant converter with a synchronous rectification function that includes a first switch; a second switch; a first transformer; a first synchronous rectifier; a second synchronous rectifier; a controller; and a second transformer. The controller of the half-bridge LLC resonant converter with a synchronous rectification function can control the first synchronous rectifier and the second synchronous rectifier directly and the connected second transformer also can control the first switch and the second switch directly. The first synchronous rectifier and second synchronous rectifier having a low conducting resistance substitute the rectifier and greatly lower the power consumption. The controller outputs a control signal to drive a transformer to output a signal to the primary winding, and its signal delay is formed by a delay of an electronic circuit and a power MOS switch of the first switch and second switch.

Abstract: A switching regulator and method of fabricating a switching regulator is disclosed. In one embodiment a switching regulator comprises a transformer having a primary winding and a secondary winding, an inductor (L) connected to an input of the primary winding, and a capacitor (C) connected across the primary winding of the transformer. The inductor and capacitor form a L-C tank circuit. The switching regulator also includes a frequency source connected to the inductor, wherein the frequency source provides a switching frequency to the inductor that is substantially equal to a resonant frequency of the L-C tank circuit.

Abstract: A single stage AC/DC converter with piezo transformer is provided. The AC/DC converter is suitable for converting an AC power into a DC power and is comprised of a rectification module, a switching module, a driving module, a piezo transformer, and an output rectification module. The present invention provides a new AC/DC converter with piezo transformer by combining the bulk circuit and the half-bridge circuit together.

Abstract: An AC/DC switching power supply that realizes a high power factor and has little voltage stress on a smoothing capacitor is provided. Also a switching power supply that has little voltage stress on a switch and is suitable for reduction in loss and miniaturization is provided.

Abstract: A switching power transmission device includes a transformer having primary and secondary windings, and two driving windings, the transformer being connected with an inductance and a capacitor. First and second switch circuits are connected to input power and the transformer so as to switch the current flow in the primary winding to produce a switched output on the secondary winding. A current, flowing through the first switching device, is detected by a current detecting device to control the current flow based on the detected value of the current.

Abstract: A DC-DC converter has an output bus coupled to power a load. A voltage transient compensation circuit has a first switch between a voltage input bus and the output bus, and a second switch between the output bus and a flyback transformer coupled to a reference voltage terminal. When the voltage on the output bus drops below a first threshold, the first switch couples and thereby transfers energy from the voltage input bus to the voltage output bus and the load. When the voltage on the output bus exceeds a second threshold, the second switch is closed, transferring energy from the output bus to an input winding of the flyback transformer. When the voltage on the output bus drops back in a range between the two thresholds, the second switch is opened, and the flyback transformer transfers stored energy back to the voltage input bus.

Abstract: First and second semiconductor switches which are activated alternately are provided between ends of a primary winding and a common potential point, wherein a DC power supply voltage is supplied to a center tap. An electric current flowing into a load is fed back to thereby subject the semiconductor switches to PWM control. Series circuits consisting of capacitors and semiconductor switches are connected between the center tap of the primary winding and the ends of the same. The semiconductor switches are activated in synchronism with the first and second semiconductor switches, thereby preventing occurrence of an anomalous high voltage, which would otherwise be caused at the time of switching operation.

Abstract: The present invention relates to a power unit with a self-oscillating series resonance converter for feeding of a load. The series resonance converter comprises: two transistors TR1, TR2 coupled together, which are arranged to individually be affected by a control transformer T1, a series connection of an inductor L1 and a capacitor C4, and means to change the oscillating frequency of the transistors TR1, TR2 and thereby the output voltage of the power unit. Each transistor TR1, TR2 together with the series coupled discharging capacitor C6, C7 or additional transistor TR3, TR4 belonging thereto is connected in parallel with said inductor L1, capacitor C4 and control transformer T1. The means to change the oscillating frequency of the transistors comprises a control oscillator OSC that in an alternating manner sends pulses that turns off the transistor TR1, TR2 that conducts current and thereby the oscillating frequency of the transistors is controlled by the pulse frequency of the control oscillator OSC.

Abstract: A method and apparatus for preventing current flow through the integral body diode of an electronic switch (e.g. MOSFET) in the secondary circuit of a synchronous rectifier. In a conventional synchronous rectifier, body diode current 31a 31b occurs during dead times 32a 32b. In the present invention, current steering pulses 40 are applied to the secondary circuit to oppose freewheeling current flow through the integral body diode. The current steering pulses produce a current that maintains the body diode in a reverse-biased state. Also, body diode current 31a 31b is prevented in the invention by short-circuiting a primary winding 19 of a transformer. The present invention prevents body diode conduction energy losses, as well as reverse recovery losses. The present invention is applicable to many different kinds of synchronous rectifiers such as current doubling rectifiers, center-tapped rectifiers, full bridge rectifiers.

Abstract: An object of the present invention is to provide a small size output transformer capable of producing sine wave oscillation at stability and high efficiency. A drive circuit including a switching circuit is connected to DC power source input units 12a, 12b, and an output transformer 10 is connected to the drive circuit. At the drive circuit, the switching circuit is turned on and off on the basis of a feedback signal of the primary side resonance voltage induced in the input side primary winding of the output transformer. The energizing direction of the DC power source to the output transformer is converted in clockwise and counter-clockwise direction by the on and off of the switching circuit, and the power source is applied as the AC signal to the input side primary winding of the output transformer. The phase detecting means detects the phase of the resonance waveform at the primary side of the output transformer 10 and outputs the phase signal.

Abstract: A non-contact power supply device having a primary unit and a secondary unit of a coupling transformer for driving a load such as decoration lamps. The primary unit is installed inside of premises and the secondary unit is installed outside of the premises and the decoration lamps are connected to the secondary unit. The primary unit and the secondary unit are attached to an intervening body such as a window or a wall in a face-to-face fashion. The non-contact power supply device is able to control and change an output voltage of the secondary unit and lighting patters of the decoration lamps solely from the inside of the premises without need for a user to go outside.

Abstract: A switching power supply is provided in two stages with the primary of the power transformer being in the first stage and the secondary in the second stage. The first stage includes an EMI filter connected to the input of a rectifier. The output of the rectifier is connected to a self oscillating, half-bridge, resonant inverter operating in open loop with the primary of the transformer to provide isolation from the power source. Feed-forward control is used to compensate for line variations, providing very small output voltage variation compared with input voltage variation. In the second stage, the secondary of the transformer provides an input to post regulator circuitry including a PWM control circuit to regulate the output current using the error signal representing the differences between the current sensed and the desired value.

Abstract: Single, multistage, and distributed magnetic switched and tank resonant power conversion systems use a non saturating magnetic element (NSME). The NSME provide superior protection to conducted lightning transients, superior thermal operating bandwidth, higher magnetizing efficiency, greater flux/power density potential and form factor flexibility when implemented with the disclosed circuit strategies. Output voltage is maintained substantially constant and ripple free in the presence of line and load variations by the action of various feedback strategies. These mechanisms combine to produce compensations by controlling the duration and/or frequency of a switch or switches. A novel function generator implementation supplies a signal which is a function of magnetic flux tracking, AC line phasing, and output voltage feedback to provide output regulation, active ripple rejection, and power factor correction to the AC line.

Abstract: A pair of equivalent controlled impedance buffers are connected in a push-pull configuration to a transformer primary coil. A pair of equivalent pre-drivers are connected to the pair of buffers. Each pre-driver receives a driver input signal and outputs a buffer input signal (based on the input signal) and a DC offset compensation signal. Each buffer receives the buffer input signal from its associated pre-driver for buffered output as a line driver signal to the primary coil. Each buffer further receives the DC offset compensation signal generated its pre-driver to compensate for an offset introduced by the transformer. A balanced bridge hybrid is also connected between the buffer output and internal nodes. An adjustment circuit processes the hybrid output during training mode to generate an adjustment signal for application to an adjustable current source within each buffer.

Abstract: In prior art, the operation of the switching transistors Q1 and Q2 is within a range of class-AB to class-B and they are not good at efficiency since it is difficult to change the operating point thereof. There is disclosed an innovative switching power circuit which is self-oscillated by a tertiary winding N3 so that each of the pair of switching elements Q1 and Q2 may be conducted alternately and thereby a current flowing from the centertap is switched so as to selectively flow alternately to one side of the primary winding N1 or to other side thereof to generate an AC voltage on a secondary winding N2, said switching power circuit characterized by that an operating point of the switching elements Q1, Q2 is changed from that in starting by using a DC voltage generated by a switching operation of the switching elements Q1, Q2 as an inverse bias power source for the switching elements Q1, Q2.