Abstract: Power supplies, power adapters, and related methods are disclosed. One example power supply includes an open loop DC to DC converter having an input for connecting to an input power source and an output for supplying a DC output voltage or current and an enable/disable circuit coupled to the open loop DC to DC converter. The enable/disable circuit is configured to enable and disable the open loop DC to DC converter as a function of the DC output voltage or current. One example method includes determining a DC output voltage or current from an open loop DC to DC converter and enabling and disabling the open loop DC to DC converter as a function of the determined DC output voltage or current.

Abstract: There is provided an interleaved type power factor correction circuit having a transformer forming a separated winding structure, which is formed by integrating two inductors separately wound around the transformer. The interleaved type power factor correction circuit including a rectifying unit rectifying a commercial alternating current power, a transformer having a first inductor winding and a second inductor winding, a bobbin part, and a core part, a switching unit switching a power transmitted to the first and second inductor windings, a controlling unit controlling a switching operation of the switching unit in order to allow a phase difference between a current and a voltage of the switched power to satisfy a predetermined phase difference, and a stabilizing unit stabilizing the switched power from the switching unit.

Abstract: There is provided a boost converter capable of reducing internal pressure in elements without the employment of a separate snubber by clamping a voltage, transmitted to the elements, to a charging voltage or an output voltage during power conversion. The boost converter includes a transformer including a primary winding receiving input power and a secondary winding electromagnetically coupled to the primary winding and having a predetermined turns ratio therewith; a switching part allowing the input power transmitted to the primary winding to be on or off according to a predetermined switching duty; a clamping part including a link capacitor charged with the input power obtained when the switching part is switched on, and power transformed based on the predetermined turns ratio; and a stabilizing part stabilizing power outputted from the clamping part.

Abstract: The present invention relates to a hold-up time expansion circuit and a converter including the same. The hold-up time expansion circuit controls switching frequency of at least one switch according to the input voltage of the converter. The converter is dependent on the switching frequency that is controlled by the hold-up time expansion circuit, and controls the duty of at least one switch according to the feedback signal of the output voltage.

Abstract: An active clamp DC-DC converter includes a transformer having a primary coil and a secondary coil, a main switching device connected in series to the primary coil of the transformer so that the main switching device and the primary coil are connected in parallel to a DC power source, a reset capacitor, a reset switching device connected in series to the reset capacitor so that the reset switching device and the reset capacitor are connected in parallel to the primary coil of the transformer, a rectifying circuit connected to the secondary coil of the transformer, a smoothing circuit connected to the rectifying circuit, and a control circuit adjusting a dead time that elapses from the time when the reset switching device is turned off until the time when the main switching device is turned on, based on a voltage across the main switching device.

Abstract: A current detection circuit that includes a winding part including a core provided on a switching element and a lead wire which is wound around the core, and a signal generation unit configured to generate a signal with a value having correlation to a current passing through the switching element based on a current passing through the lead wire.

Abstract: Soft-switching is performed to switch a switching state to an ON state by controlling a delay time of a timing at which a main switch switches to an ON state relative to a timing at which a sub-switch switches to an ON state. Controllability of soft-switching decreases as a result of variations in time difference of a command for switching the main switch to the ON state and the actual switching of the switching state. To set a delay time suitable for performing soft-switching based on the variations in time difference, an EEPROM is provided that stores therein correction data for the delay time. The delay time of the timing of the command for switching the main switch to the ON state relative to the timing of the command for switching the sub-switch to the ON state is set based on the correction data.

Abstract: An embodiment of the invention relates to a power converter including a resistor divider with an internal node to sense an input line voltage. The internal node is operable as a multifunctional pin. A controller compares a feedback voltage dependent on a power converter output characteristic to a current-sense signal including an offset dependent on a voltage of the internal node to control entry and exit of the power converter from burst mode operation. The node may be employed to manage power converter operation by sensing or controlling its voltage to signal operation in a standby or burst mode, to sense the input line voltage, to enable an external system to signal shutdown to the power converter, and to enable the power converter to signal a delayed restart condition to the external system.

Abstract: A cord correction circuit in a primary-side-controlled flyback converter compensates for the loss of output voltage caused by the resistance of the charger cord. In one embodiment, a correction voltage is subtracted from a feedback voltage received from a primary-side auxiliary inductor. A pre-amplifier then compares a reference voltage to the corrected feedback voltage. In another embodiment, the correction voltage is summed with the reference voltage, and the pre-amplifier compares the feedback voltage to the corrected reference voltage. The difference between the voltages on the input leads of the pre-amplifier is used to increase the output voltage to compensate for the voltage lost through the charger cord. The flyback converter also has a comparing circuit and a control loop that maintain the peak level of current flowing through the primary inductor of the converter. Adjusting the frequency and pulse width of an inductor switch signal controls the converter output current.

Abstract: A reset voltage circuit for a forward power converter includes a reset capacitor and a memory capacitor. The reset capacitor is to be coupled to recycle energy from a primary winding of a transformer to an input bulk capacitor during a resetting of the transformer. The memory capacitor is to be coupled to store a first voltage equal to an input voltage of the power converter when the input voltage is at a steady-state value. The memory capacitor is further to set a voltage across the primary winding during the resetting of the transformer to a magnitude greater than or equal to the first voltage when the input voltage of the forward power converter drops below the steady-state value.

Abstract: A compensation circuit and a compensation method for providing compensation of a power converter are proposed. A current sense circuit is coupled to receive a switching current for generating a current signal. A signal generation circuit is developed to generate a first compensation signal and a second compensation signal for adjusting the current signal. The first compensation signal is coupled to adjust the current signal for the output power limit of the power converter. The second compensation signal is coupled to adjust the current signal for the slope compensation. The slope of the first compensation signal is decreased when the power transistor is turned on. The slope of the second compensation signal is increased in response to the turn on of the power transistor.

Abstract: An electric power converter facilitates performing soft switching in the two-way electric-power-conversion operation thereof, and reducing the manufacturing costs thereof and the losses caused therein, The electric power converter includes a first switching device; a second switching device; a first series circuit including capacitor, a diode, the primary winding of transformer, and a third switching device; a second series circuit including a capacitor, a fourth switching device, the primary winding of transformer, and a diode; a third series circuit including a diode and the secondary winding of transformer; and a voltage clamping element connected in parallel to the primary winding of transformer. The first series circuit is connected in parallel to the first switching device, and the second series circuit is connected in parallel to second switching device. The third series circuit is connected between the DC output terminals.

Abstract: A power supply apparatus with a current-sharing function includes a conversion circuit, a square-wave generating circuit, a resonant circuit, and a rectifier-filter circuit. The conversion circuit has two transformers, and each of the transformers has a primary winding and two secondary windings. More particularly, two secondary windings of the different transformers are electrically connected in series and then the two in-series secondary windings are electrically connected in parallel. The square-wave generating circuit is used to switch a DC voltage into a pulsating voltage. The resonant circuit is electrically connected to the square-wave generating circuit, and having a first capacitor and the primary windings of the transformers.

Abstract: This DC-DC converter circuit includes a switching circuit which switches a DC power supply with a primary side switching element, a transformer to a primary side winding whereof the output of the switching circuit is applied and which outputs a voltage which has been changed by a predetermined voltage change ratio to a secondary side winding, and secondary diodes for current adjustment connected to the secondary side winding of the transformer. Moreover, it includes a regeneration snubber circuit connected in parallel with the secondary diode circuit and including a series circuit of a discharge blocking diode and a snubber capacitor and a switching element for regeneration connected in parallel with the discharge blocking diode, a filter circuit connected between rectification outputs of the secondary diode circuit, and a control unit which turns the switching element for regeneration ON a predetermined time period after the timing of turning the primary side switching element OFF.

Abstract: An electrically insulated switching element driver includes: a pulse transformer driving unit into which a switching element driving signal and a duty signal are input and which drives, in accordance with the duty signal, a first or second pulse transformer that is selected depending on a state of the switching element driving signal; a first edge detection unit that outputs an on-off signal according to an edge in a pre-rectification output of the first pulse transformer; a second edge detection unit that outputs an on-off signal according to an edge in a pre-rectification output of the second pulse transformer; and a control driving unit that drives a switching element to be driven, based on the output of the first and second edge detection units, wherein the first and second edge detection units and the control driving unit operate with power resulting from rectifying the output of the first and second pulse transformers.

Abstract: An inductor current flows through an inductor of a flyback converter. In a constant voltage mode, the pulse width of an inductor switch control signal is adjusted to maintain a constant output voltage of the flyback converter. The inductor switch control signal controls a switch through which the inductor current flows. In a constant current mode, a comparing circuit, a control loop and a clamp generator circuit are used to maintain the peak level of inductor current. The comparing circuit generates a timing signal based on the ramp-up rate of the inductor current. The control loop uses the timing signal and a feedback signal to generate a time error signal. The clamp generator circuit uses the time error signal to generate a clamp signal that adjusts the pulse width of the inductor switch control signal to clamp the peak current output by the flyback converter in the constant current mode.

Abstract: A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings.

Abstract: An controller for use in a power supply includes a variable oscillator and a digital-to-analog converter (DAC). The variable oscillator generates a switching signal having an on-time and a switching period to control a first switch to regulate an output of the power supply. The DAC provides the variable oscillator with a first analog signal and a second analog signal, where the on-time of the switching signal is responsive to the first analog signal and where the switching period is responsive to the second analog signal. The DAC includes a current source and a second switch that is configured to couple the current source to provide current to the first analog signal in response to a binary digit received by the DAC, and to couple the current source to provide current to the second analog signal in response to a complement of the binary digit.

Abstract: In one embodiment, a power converter system comprises an input terminal operable to connect to a DC power source and an output terminal at which an output voltage can be provided. An active clamped forward converter is operable to provide forward power flow from the DC power source to the output terminal. A flyback converter is operable to provide backward power flow from the output terminal to the DC power source. The active clamped forward converter and the flyback converter cooperate to generate a rectified sinusoidal waveform at the output terminal.

Abstract: Control devices can be destroyed or damaged by their supply voltage in the event of malfunction. The voltage supply according to the present invention comprises a means (12) having a primary part (121) and secondary part (122), the primary part (121) being connected to the voltage source (10) and being controllable by means of the voltage output (112) of the voltage converter (11), and the secondary part (122) comprising a first and a second mutually independent winding, a supply voltage for the control device being made available by means of the first winding, and the second winding being connected to the voltage input (111) of the voltage converter (11) so that a supply voltage, additional to the voltage source (10), for the voltage converter (11) is implemented by means of the second winding.

Abstract: A switching power supply apparatus includes a PFC converter, a DC-DC converter, and primary-side and secondary-side digital control circuits that control the PFC converter and the DC-DC converter. On the basis of a voltage detected by an output voltage detection circuit, the primary-side digital control circuit transmits data about the on-time of a switching element of the DC-DC converter to the primary-side digital control circuit. On the basis of this data, the primary-side digital control circuit controls the on-time of the switching element.

Abstract: A boost device boosts an input voltage to an output voltage across an output capacitor, and includes an output diode coupled to the output capacitor, and a transformer coupled to a first switch, a clamp circuit and a boost circuit. The clamp circuit is coupled across a first winding of the transformer, and includes a clamp capacitor coupled in series to a second switch. The output capacitor is capable of being charged through the output diode with an induced voltage across a second winding of the transformer. The boost circuit is capable of being charged with the induced voltage across the second winding, and of charging the output capacitor so as to boost the output voltage across the output capacitor.

Abstract: The present invention discloses a forward-flyback converter with active-clamp circuit. The secondary side of the proposed converter is of center-tapped configuration to integrate a forward circuit and a flyback circuit. The flyback sub-circuit operating continuous conduction mode is employed to directly transfer the reset energy of the transformer to the output load. The forward sub-circuit operating discontinuous conduction mode can correspondingly adjust the duty ratio with the output load change. Under the heavy load condition, the mechanism of active-clamp flyback sub-circuit can provide sufficient resonant current to facilitate the parasitic capacitance of the switches to be discharged to zero. Under the light load condition, the time interval in which the resonant current turns from negative into positive is prolonged to ensure zero voltage switching function. Meanwhile, the flyback sub-circuit wherein the rectifier diode is reverse biased is inactive in order to further reduce the power losses.

Abstract: An integrated-type high step-up ratio DC-AC conversion circuit with an auxiliary step-up circuit applies to converting a low DC voltage of alternative energy into a high AC voltage. The conversion circuit uses an isolated Cuk integration unit and an auxiliary step-up unit to form a multi-phase input and uses parallel charging and cascade discharging to boost the DC voltage in the DC side with a low voltage power switches and low duty cycle and then converts the boosted DC voltage into AC voltage. The auxiliary step-up unit not only shares the entirety of power but also exempts the DC-side circuit from using high voltage power switches, whereby the cost of elements is reduced. Further, the conversion circuit can decrease the switching loss and conduction loss of the DC-side switches and promote the efficiency of the circuit.

Abstract: The isolated current regulated DC-DC converter is composed of the step down switch SA, free wheel diode DA, step down inductor L, switches S1 and S2, capacitor Cc to absorb the leakage energy of the switching transformer, output diodes D3 and D4, output filter capacitor C and the switching transformer T; one terminal of the step down inductor L is connected with the step down switch SA and free wheel diode DA, and other terminal of the step down inductor L is connected with one of primary windings of the switching transformer and switch S1 or S2; two primary windings of the switching transformer are respectively connected with switches S1 and S2 in series; two primary winding and switch S1 or S2 branches are paralleled and respectively connected with the free wheel diode DA and the step down inductor L; the free wheel diode DA is series with the step down switch SA and they connect with the input voltage Vin; the capacitor Cc to absorb the leakage energy of the switching transformer is respectively connected

Abstract: A multi-output DC-to-DC conversion apparatus with a voltage-stabilizing function includes a center-tapped main transformer, a semiconductor component group, and a triggering controller. The DC-to-DC conversion apparatus provides at least two output voltages which are a main output voltage and an auxiliary output voltage, respectively. The auxiliary output voltage is functioned as an input voltage of a buck converter; and, as a result, the auxiliary output voltage can be adjusted to obtain a lower variable DC voltage. The triggering controller is used to stabilize the main output voltage and the auxiliary output voltage. Therefore, the main transformer provides one or two secondary windings to step down the auxiliary output voltage so as to increase efficiency of the buck converter.

Abstract: An embodiment includes coupling a first intermediate node between a first inductor and a first winding of a transformer to a reference node during a first portion of a first switching cycle, uncoupling the first intermediate node from the reference node and coupling the first intermediate node to a signal-storage element during a second portion of the first switching cycle, coupling a second winding of the transformer between the reference node and a second converter node during the second portion of the first switching cycle, and regulating a signal at the second converter node by controlling a duration of one of the first and second portions of the first switching cycle. For example, in an embodiment, bidirectional signal converter may perform the above steps to handle power transfer between two loads. Such a voltage converter may have improved conversion efficiency and a smaller size and lower component count as compared to a conventional bidirectional voltage converter.

Abstract: An embodiment of a multidirectional signal converter includes first and second converter nodes, a transformer, and first and second stages. The transformer includes first and second windings, and the first stage is coupled between the first converter node and the first winding of the transformer. The second stage includes a first node coupled to the second converter node, a second node coupled to a node of the second winding of the transformer, and a filter node, is operable as a boost converter while current is flowing out from the second converter node, and is operable as a buck converter while current is flowing out from the first converter node. For example, in an embodiment, such a multidirectional signal converter may be a bidirectional voltage converter that handles power transfer between two loads. Such a voltage converter may have improved conversion efficiency and a smaller size and lower component count as compared to a conventional multidirectional voltage converter.

Abstract: An embodiment of a controller for a multidirectional signal converter is operable to cause the converter to regulate a first signal at a first converter node, and to have a switch timing that is independent of a direction of power transfer between the first converter node and a second converter node. For example, in an embodiment, such a controller may be part of a bidirectional voltage converter that handles power transfer between two loads. Such a voltage converter may have improved conversion efficiency and a smaller size and lower component count as compared to a conventional multidirectional voltage converter. Furthermore, such a voltage converter may be operable with a common switching scheme regardless of the direction of power transfer, and without the need for an indicator of the instantaneous direction of power flow.

Abstract: A method of assembling an electric power system includes coupling a power converter to an electric current source. The method also includes coupling a stationary portion of a rotary transformer to the power converter. The method further includes coupling a rotatable portion of the rotary transformer to a load device.

Abstract: We describe a switching power converter comprising a bipolar switching device (BJT or IGBT) switching an inductive load, and including a closed-loop control system. The control system comprises a voltage sensing system to sense a voltage on a collector terminal of the switching device and provide a voltage sense signal; a controller; and a drive modulation system coupled to an output of the controller for modulating a drive to the control terminal of said bipolar switching device responsive to a controller control signal; wherein said controller is configured to monitor changes in the sensed voltage during a period when said switching device is switched on and to control said drive modulation system to control the degree of saturation of said bipolar switching device when the device is switched on and hence improve turn-off times.

Abstract: A control circuit for use in a power converter in one aspect limits the magnetic flux in a transformer. Controlled current sources produce a first current that is proportional to an input voltage of the power converter and a second current that is proportional to a reset voltage of the transformer. An integrating capacitor is charged with the first current and discharged with the second current, where a voltage on the capacitor is representative of the magnetic flux in the transformer. A logic circuit is adapted to turn off the switch when the voltage on the integrating capacitor is greater than or equal to a first threshold voltage, and to allow the switch to turn on and off in accordance with a pulse width modulation signal after a delay time that begins when the integrating capacitor discharges to a second threshold voltage.

Abstract: A multiple output switching power source apparatus includes first and second switching elements Q1 and Q2, a first series resonant circuit connected in parallel with Q1 or Q2 and having a first current resonant capacitor and a primary winding of a transformer that are connected in series, a first rectifying-smoothing circuit to rectify and smooth a voltage generated by a secondary winding of the transformer, a second series resonant circuit connected in parallel with the secondary winding and having a second current resonant capacitor and a second resonant reactor that are connected in series, a second rectifying-smoothing circuit to rectify and smooth a voltage of the second series resonant circuit, and a control circuit to determine an ON period of Q1 according to a voltage obtained from one of the first and second rectifying-smoothing circuits, determine an ON period of Q2 according to a voltage obtained from the other of the first and second rectifying-smoothing circuits, and alternately turn on/off Q1 an

Abstract: A display apparatus, a power supply apparatus and a power supply method are provided. The display apparatus display apparatus includes: a signal receiving unit which receives an image signal; a signal processing unit which processes the image signal; a display unit which displays an image based on the image signal processed by the signal processing unit; and a power supply unit which receives AC power and supplies operation power to the display unit. The power supply unit includes a discharging circuit part which includes a discharging element which discharges the power supply unit to remove a residual voltage from the power supply unit when the AC power is suspended, the discharging circuit part preventing the discharging element from consuming power when the AC power is input. It is possible to minimize wasteful power consumption caused by a discharging element provided to guarantee user's safety against a residual voltage.

Abstract: A transformer includes a first secondary winding, a second secondary winding, and a third secondary winding. The second secondary winding and the third secondary winding are wound to include the same number of turns and to have opposite magnetic polarities. A low-pass filter includes a second inductor defined by a leakage inductance of the second secondary winding connected in series with the second secondary winding, a second inductor defined by a leakage inductance of the third secondary winding connected in series with the third secondary winding, and a second capacitor. An output voltage is output from an output terminal of the low-pass filter.

Abstract: A switching element driving control circuit includes: a regulator circuit which generates a power supply voltage having an amplitude; a capacitor which smoothes the power supply voltage generated by the regulator circuit to remove a high frequency component; a circuit power supply line to which the smoothed power supply voltage is supplied; an oscillation circuit which generates a periodic signal according to an oscillation of the power supply voltage supplied from the circuit power supply line; a control circuit which generates a control signal for controlling the switching operation of the switching element, based on the periodic signal; and a driver circuit which supplies the switching element with the control signal.

Abstract: A voltage detection device that is connected to a DC circuit to which a DC voltage is applied and that detects the DC voltage applied to the DC circuit includes a voltage conversion unit for outputting a first voltage that increases as the DC voltage increases and a second voltage that decreases as the DC voltage increases, an error detection unit for detecting an error for the first voltage and the second voltage based upon the first voltage and the second voltage when the DC voltage is 0, and a voltage calculation unit for correcting a difference between the first voltage and the second voltage based upon the error detected by the error detection unit and calculating the DC voltage based upon the corrected difference between the first voltage and the second voltage.

Abstract: A control device for controlling a switch unit of a resonant direct current/direct current converter includes a frequency modulation controller and a pulse selector. The frequency modulation controller is adapted to be coupled electrically to the converter for receiving a correcting threshold value and output information of the converter, and for generating a synchronization signal according to the correcting threshold value and the output information received thereby. The pulse selector is adapted to be coupled electrically to the converter and the frequency modulation controller for receiving the correcting threshold value, the output information and the synchronization signal, and for generating a driving signal according to the correcting threshold value, the output information and the synchronization signal received thereby. The driving signal is adapted to drive the switch unit and has a working period.

Abstract: A switch-mode converter including an inductive transformer having a secondary winding associated with at least one first switch, including, in parallel with the first switch, at least one first diode in series with a capacitive element; and in parallel with the capacitive element, an active circuit for limiting the voltage thereacross.

Abstract: A power supply device having zero switching voltage is disclosed to include a first switch having a parasitic body diode, a first capacitor, an inductor, a transformer, a second switch having a parasitic body diode, a second capacitor, a first voltage output unit providing a first voltage output, and a second voltage output unit having a third switch and providing a second voltage output. By means of controlling the order in which the first switch, the second switch and the third switch are to be switched on, switching voltage is eliminated from the first switch and the second switch and the working efficiency of the power supply device is raised.

Abstract: A single-ended forward converter of the present invention, has first and second switching element comprises a pair Lus N-Channel FET, a first driving circuit comprises the series-connected circuit of the first voltage drop resistor and first zener diode for driving first Lus N-Channel FET, a second driving circuit comprises the series-connected circuit of the second voltage drop resistor and second zener diode for driving second Lus N-Channel FET.

Abstract: This current balanced push-pull type inverter circuit includes first and second switching elements, and an output transformer which includes a first primary winding and a second primary winding connected in series between said first and second switching elements, and also includes a secondary winding for obtaining an output voltage. This inverter circuit also includes a first voltage supply capacitor, a second voltage supply capacitor, and a control unit. A first snubber circuit, in which a first free wheel diode and first and second snubber capacitors are connected in series, is connected in inverse parallel to the first switching element. A first discharge resistor is connected between the first snubber capacitor and a first power supply capacitor, and a second discharge resistor is connected between the second snubber capacitor and a third power supply capacitor. And a second snubber circuit and discharge resistors are connected to the second switching element as well, in a similar manner.

Abstract: In embodiment, a power supply system is configured to use a linear regulator to form a regulated voltage during a standby mode and to use the regulated voltage to form another regulated voltage.

Abstract: Various embodiments of apparatus and systems are provided for electrically isolating two devices while transferring power and RF signals therebetween. An electrical isolation apparatus includes an isolation transformer that operates to transfer electrical power between first and second devices. The electrical isolation apparatus also includes a decoupling device that transfers radio frequency (RF) signals between the first and second devices. The isolation transformer and the opto-isolator cooperatively operate to electrically isolate the first device from the second device.

Abstract: A switching power supply device includes a first series circuit of first and second switching elements connected in parallel with a DC power supply. An isolation transformer has primary and secondary windings and first and second auxiliary windings, a first layer including the primary windings between a second layer of the two auxiliary windings, and a third layer of the secondary windings. A capacitor in series with the primary windings defines a second series circuit in parallel with the second switching element. A rectifying and smoothing circuit includes a rectifying diode and a smoothing capacitor, connected to the secondary windings. First and second control circuits turn on and off the first and second switching elements based on voltages generated in the two auxiliary windings, to obtain a DC output from the rectifying and smoothing circuit, enabling an adequate auxiliary windings voltage and stable switching operation including stable zero-voltage turn-on.

Abstract: A DC-DC converter using a plurality of transformers capable of decreasing the loss, preventing heat generation of transformers, and improving the heat transfer property of the core, and an integrated type transformer used in this DC-DC converter. A terminal T1 in which a negative electromotive force is generated and a terminal TR2 in which a positive electromotive force is generated, while a switching element Q1 is conducting, are connected at a node N1. An output coil L1 and output terminals TO1 and TO2 are provided on a current route shared by transformers T1 and T2. Diodes D1 and D2 are respectively inserted in a forward direction from a node N3 toward a terminal TR3 and in a forward direction from the node N3 toward a terminal TR4. An operation of a first transformer and an operation of a second transformer are respectively assigned to a flyback operation and a forward operation.

Abstract: A switching power supply includes: a transformer including primary and secondary windings; a switching circuit including first and second switching elements, first and second rectifying elements, first and second capacitive elements and a first inductor; and a rectifying/smoothing circuit. A first bridge circuit is configured by the first and second switching elements located in a diagonal arrangement and the first and second capacitive elements also located in a diagonal arrangement. The first and second rectifying elements are connected in parallel to the first and second switching elements, respectively. One of the first and second rectifying elements is in forward direction and other is in inverse direction. The first inductor is disposed on a connection line between the pair of input terminals and the first bridge circuit. The primary winding is connected to the first bridge circuit to form a H-bridge configuration. The secondary winding is disposed in the rectifying/smoothing circuit.

Abstract: A switch mode power supply according to the invention that can improve the reliability thereof includes a series circuit connected between the positive and negative electrodes of a DC power supply 3, the series circuit including a capacitor 4, a main switching device 1, and a subsidiary switching device 2; a main control circuit 13; a subsidiary control circuit 10; control circuits 13 and 10 turning main switching device 1 and subsidiary switching device 2 alternately ON and OFF to obtain a DC output via a transformer 6; and subsidiary control circuit 10 preventing a voltage exceeding the gate breakdown voltage of subsidiary switching device 2 from being applied to the gate electrode of subsidiary switching device 2.

Abstract: A switched mode power converter is provided which includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b); a primary side active switch device (S1) coupled to the primary winding for selectively applying an input voltage to the primary winding; and a secondary side rectifier circuit including an output filter (6, 12) coupled to the at least one secondary winding (2), and first and second active switch devices (16, 14) coupled between the at least one secondary winding (2b) and the output filter. The switch devices are arranged such that each one is operable independently of the other to block current between the at least one secondary winding and the output filter in an opposite direction to the other. This facilitates better regulation of the converter and avoids the occurrence of voltage spikes encountered in existing configurations.

Abstract: A cord correction circuit in a primary-side-controlled flyback converter compensates for the loss of output voltage caused by the resistance of the charger cord. In one embodiment, a correction voltage is subtracted from a feedback voltage received from a primary-side auxiliary inductor. A pre-amplifier then compares a reference voltage to the corrected feedback voltage. In another embodiment, the correction voltage is summed with the reference voltage, and the pre-amplifier compares the feedback voltage to the corrected reference voltage. The difference between the voltages on the input leads of the pre-amplifier is used to increase the output voltage to compensate for the voltage lost through the charger cord. The flyback converter also has a comparing circuit and a control loop that maintain the peak level of current flowing through the primary inductor of the converter. Adjusting the frequency and pulse width of an inductor switch signal controls the converter output current.