Abstract: A system for sensing voltage in an isolated converter includes an input circuit isolated from an output circuit using a first transformer, the first transformer having a primary coil and a secondary coil, wherein the output circuit includes an output inductor and an output capacitor, and wherein the input circuit includes a power source that provides power to the output circuit through the first transformer; a feedback winding coupled to the output inductor to form a second transformer; and a monitor circuit that calculates a voltage across the output capacitor using a voltage across the feedback winding, a voltage across the primary coil of the first transformer, a turns ratio of the first transformer, and a turns ratio of the second transformer in order to provide feedback to control the input circuit.

Abstract: The embodiments herein describe a switched mode power converter. In particular, the embodiments herein disclose a method for powering a synchronous rectifier controller that enables synchronous rectification in the switched mode power converter. The synchronous rectifier controller may be enabled by a regulator circuit or directly from the output voltage.

Abstract: A method for managing an alternating current adaptor system is disclosed. A direct current voltage is received at a high impedance power delivery network from a primary side of an alternating current adaptor system. An isolated voltage is output from the high impedance power delivery network to components of a secondary side of the alternating current adaptor system. A transition in a power state identification of an information handling system associated with the alternating current adaptor system is detected. An output voltage level of the alternating current adaptor system is alternated in response to the transition in the power state identification of the information handling system.

Abstract: The present invention relates to a power converter (90) and a method of operating same. There are numerous advantages to operating power converters using a series resonant converter (1, 21). This approach is particularly suitable for minimizing switching losses in the power converter when it is operated at high frequency. However, there are problems with the known converters in that they are prone to generate noise in the acoustic spectrum due to the fact that the converter stages are often operating at different frequencies. The present invention relates to a power converter and a method of operating same that enables the operating frequency of the converter to be controlled by a control circuit over a predetermined range of the resonant frequency. This allows reduction in acoustic noise generation and facilitates frequency smearing that will in turn reduce spectral peaks. This is achieved while maintaining output ripple within acceptable ranges.

Abstract: An embodiment apparatus comprises a secondary synchronous rectifier and a secondary gate drive controller. The secondary gate drive controller coupled to a transformer winding comprises a secondary synchronous rectifier soft start signal generator configured to generate a plurality of soft start pulses, a pulse width modulation generator configured to generate a forward switch drive signal and a freewheeling switch drive signal based upon a signal across the transformer winding and a soft transition generator configured to generate a soft start freewheeling switch drive signal by gradually releasing the freewheeling switch drive signal during a soft start process.

Abstract: A pulsed drive signal without a dead band can be achieved by a drive circuit arranged to receive opposite pulsed input signals, having a dead band between them, a transformer arranged to receive the input signals and output intermediary signals, time delay circuitry arranged to receive the intermediary signals, and to provide buffer input signals, corresponding to the intermediary signals, but with a ramped up transition from a low to a high signal, a first and a second buffer stage arranged to receive the first and second buffer input signals, respectively, and produce the first and the second drive output signal corresponding to the first and second pulsed input signal but with the transition from a high to a low signal delayed to reduce the dead band.

Abstract: One embodiment relates to an LLC resonant power converter system. The system includes a transformer comprising a primary inductor and a secondary inductor and a switch control stage configured to generate a plurality of switching signals having a duty-cycle. The system also includes an input stage comprising the primary inductor and a plurality of switches that are controlled in response to the respective plurality of switching signals to generate a primary resonant current and an output stage comprising the secondary inductor and being configured to conduct an output current through a load based on a secondary resonant current to generate an output voltage. The system further includes a controller configured to limit a magnitude of the output current to a predetermined magnitude in response to variations of the load.

Abstract: A DC-DC converter includes a regeneration snubber circuit. The snubber circuit is connected in parallel with the secondary diode circuit and includes a series circuit of a discharge blocking diode, a snubber capacitor, and a switching element for regeneration connected in parallel with the discharge blocking diode. The DC-DC converter further includes 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. The predetermined time period is set to approximately the time period during which the charge, accumulated in the snubber capacitor due to reverse recovery time when one of the secondary diodes has been turned off, discharges.

Abstract: Disclosed herein is an electric generating system using a solar cell which converts a voltage generated in the solar cell into an Alternating Current (AC) voltage, and applies the converted voltage to a power system. The electric generating system includes; a Direct Current (DC)/DC converter that converts the voltage generated in the solar cell into a DC voltage, and has a synchronous rectifier including a synchronous switch; and a controller that detects one of a phase and a voltage of the power system, and selectively connects the synchronous switch of the synchronous rectifier in accordance with one of the phase and voltage of the power system. Here, the electric generating system reduces a conduction loss, and increases overall efficiency of the electric generation system.

Abstract: A synchronous rectifying circuit for a switching power converter is provided. The synchronous rectifying circuit includes a power transistor, a diode, and a control circuit. The power transistor and the diode are coupled to a transformer and an output of the power converter for rectification. The control circuit generates a drive signal to switch on the power transistor once the diode is forward biased. The control circuit includes a monitor circuit. The monitor circuit generates a monitor signal an off signal to switch off the power transistor in response to a pulse width of the drive signal for generating an off signal to switch off the power transistor. The monitor circuit further reduces the pulse width of the drive signal in response to a change of a feedback signal. The feedback signal is correlated to an output load of the power converter.

Abstract: In a switching power-supply apparatus, a primary-side power converter circuit includes a half bridge system and a synchronous rectifier circuit is provided as a rectifier circuit of a secondary-side power converter circuit. An on time ratio of the on time of a first switching element to the on time of a second switching element is controlled so as to provide an operation mode in which energy is regenerated from the secondary side to the primary side when the load is light.

Abstract: An energy recovery snubber circuit for use in switching power converters. The power converters may include a switch network coupled to a primary winding of an isolation transformer, and rectification circuitry coupled to a secondary winding of the isolation transformer. The energy recovery snubber circuit may include clamping circuitry that is operative to clamp voltage spikes and/or ringing at the rectification circuitry. The clamped voltages may be captured by an energy capture module, such as a capacitor. Further, the energy recovery snubber circuitry may include control circuitry operative to return the energy captured by the energy capture module to the input of the power converter. To maintain electrical isolation between a primary side and a secondary side of the isolation transformer, a second isolation transformer may be provided to return the captured energy back to the input of the power converter.

Abstract: A control circuit for switching power converters with synchronous rectifiers is disclosed for providing start-up and shut-down protection. The control circuit for switching power converters with synchronous rectifiers includes a means for blocking the driving signals to the synchronous rectifiers, a voltage sampling circuit, a reference voltage, and a comparator. The comparator compares a sample voltage to a reference voltage to determine when to block and when to admit driving signals to the synchronous rectifiers. The control circuit for switching power converters with synchronous rectifiers is particularly useful for minimizing component damage due to start-up and shut-down transients as compared to converters known in the art.

Abstract: A method and apparatus for conversion of high voltage AC to low voltage high current DC without using high voltage capacitors or transformers. A single switch is used to perform both the functions of pre-regulation and switching conversion. An input voltage detector determines when the input power AC is below a predetermined voltage limit. A threshold voltage generator provides a threshold voltage corresponding to the output voltage. A voltage comparator coupled to the input voltage detector and threshold voltage generator enables a pulse generator to activate the switch to gate a number of pulses of the input power below the predetermined voltage limit at predetermined frequency to a transformer. The converter regulates its output voltage by changing the input voltage threshold at which it starts switching, instead of using PWM or other known regulation technique.

Abstract: A power supply device includes a primary circuit that includes two primary windings, a secondary circuit that includes two secondary windings and a switching element for synchronous rectification, a first transformer configured to couple one of the two primary windings with one of the two secondary windings, a second transformer configured to couple the other one of the two primary windings with the other one of the two secondary windings, and a first substrate on which both output ends of one of the two secondary windings and both output ends of the other one of the two secondary windings are disposed to face each other, wherein the switching element for synchronous rectification is disposed in a region between the first transformer and the second transformer on the first substrate.

Abstract: A circuit arrangement includes a transformer, having primary windings and secondary windings, and a high voltage capacitor. A first switching circuit couples the high voltage capacitor to the primary windings. A first controller is operatively coupled to the switching circuit. A second switching circuit couples the secondary windings to an output port. A second controller is operatively coupled to the secondary windings. A high voltage generator is provided to charge the high voltage capacitor.

Abstract: A system for increasing parallel rectifier DC power system efficiency. In one embodiment, the system includes: (1) a controller configured to sense and classify a load magnitude change into groups including large load transients and moderate load transients and (2) at least one rectifier coupled to the controller and configured to transition from a stand-by mode to an active mode upon an occurrence of one of a large load transient and a moderate load transient.

Abstract: An adaptive dead time (ADT) control scheme for use with a switch mode power converter having a full bridge with synchronous rectifiers topology. A controller which implements the control scheme includes an input circuit arranged to receive a signal representative of the converter's output voltage, and an output circuit arranged to operate the converter's switching elements and synchronous rectifiers to produce a desired output voltage. The controller is further arranged such that the converter's “dead time” is adaptively varied in an inverse relationship to the magnitude of the load current. In a preferred embodiment, the signals used to operate the synchronous rectifiers are PWM signals, and the controller adaptively varies the dead time in a linear inverse relationship to the magnitude of the load current by modulating the rising and falling edges of the signals used to operate the synchronous rectifiers.

Abstract: A power-supply unit including a transformer, a full bridge circuit having four arm switches on a primary side of the transformer, a rectifier and smoothing circuit including two synchronous rectifier switches on a secondary side of the transformer, a choke coil, and a capacitor, an output terminal in the rectifier and smoothing circuit, a control circuit controlling ON/OFF of the four arm switches of the full bridge circuit and the two synchronous rectifier switches of the rectifier and smoothing circuit, a resonant inductor including a leakage inductor component and a parasitic inductor component on the primary side of the transformer, and a resonant capacitor, and in which the control circuit includes a timing variable unit which varies switching timings of the two synchronous rectifier switches of the rectifier and smoothing circuit based on an output current flowing in the output terminal provided in the rectifier and smoothing circuit.

Abstract: A power converting device includes a main switch, a synchronous rectifier switch, a rectifier-filter circuit which outputs an output voltage, and a synchronous rectifier control circuit which includes a sampling circuit coupled to the rectifier-filter circuit for outputting a voltage variation signal, a differential amplifier circuit that outputs an amplified signal by adding the output voltage and an offset voltage to the voltage variation signal attenuated thereby, and a comparison circuit that compares the amplified signal with the output voltage so as to output a trigger signal, such that the synchronous rectifier switch is turned on when the main switch is turned off, and is turned off prior to conduction of the main switch.

Abstract: A circuit and method for compensating for parasitic elements of a transistor. A transistor, a controller, and a compensation element are mounted to a printed circuit board. The transistor includes parasitic drain and source inductors. The compensation element may be a discrete inductor that has an inductance value equal to about the sum of the inductance values of the parasitic drain and source inductors. The magnitudes of the compensation voltage and the sum of the voltages across the parasitic drain and source inductances are substantially equal. Thus, the compensation voltage developed across the compensation inductor is used to adjust a reference voltage within the controller. A drain-to-source voltage is applied to one input of a comparator within the controller and the adjusted reference voltage is applied to another input of the comparator. An output signal of the comparator is input to drive circuitry that drives a gate of the transistor.

Abstract: A synchronous rectifier network unit and synchronous rectifying method. The synchronous rectifier network unit includes a first body diode to which a first current flows at a first time when the first current flows to a first coil, and a first transistor which is turned on after the first body diode is conducted, and to which the first current flows, and it rectifies the first current by differently controlling the turn-off time of the first transistor according to the first current.

Abstract: A DC to DC converter for controlling the on time and off time of a pair of synchronous switches, which reside in the position of output rectifiers in a half bridge transformer type circuit is provided. The circuit is actually two identical circuits, one for each half of the transformer output. The circuits consist of a voltage reference, a dual comparator, a bias switch, and drive buffer as well as biasing means for proper set up of the various parameters.

Abstract: A switching power supply device that includes a feedback terminal to which a feedback signal according to a load state is input, and a comparator which compares a terminal voltage of the feedback terminal with a reference voltage and determines whether the load state is a normal load state or a light load state. The switching power supply device also includes pull-up resistors which are connected to the feedback terminal, a switch element which switches resistance values of the pull-up resistors according to the change of the load state, and a switch element which switches the resistance values of the pull-up resistors according to whether the input voltage is high or low.

Abstract: A method and apparatus for bi-directional current sensing for a synchronous rectifier bi-directional converter system is disclosed. A first current is measured through a first synchronous rectifier via a first transformer to provide a first signal. A second current is measured through a second force synchronous rectifier via a second transformer to provide a second signal. The first signal and the second signal are DC restored to provide a first DC restored signal and a second DC restored signal respectively. A first correction current is added to the first DC restored signal to produce a first corrected signal, and a second correction current is added to the second DC restored signal to produce a second corrected signal. The first corrected signal and the second corrected signal are added to produce a combined signal.

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: The present invention provides a DC/DC converter for use with a DC input signal. The DC/DC converter includes a control signal generator, a primary and a secondary side, a voltage generating portion, a threshold voltage providing portion and a feedback signal generator. The control signal generator can control the primary side and the secondary side. The voltage generating portion can generate a surge voltage based a control signal from the control signal generator. The threshold voltage providing portion can generate a threshold voltage. The feedback signal generator can generate a feedback signal based on the surge voltage and the threshold voltage. The control signal generator can further modify control of one of the primary and secondary sides based on the feedback signal.

Abstract: The invention relates to a switched mode power converter and a method of operating such a converter A switched mode power converter according to the invention includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b) and a secondary side rectifier circuit including an output filter (6, 10) coupled to the at least one secondary winding (2b), and a secondary side active switch device (S3) coupled between the at least one secondary winding and the output filter. The converter further includes primary side and secondary side control means (12, 16, 18) for regulating the switching of the primary side and secondary side switches, respectively, and configured so as to reduce the duty cycle of the primary side switch device (S1) during a lower power mode of operation of the converter, the reduction of the duty cycle of the primary side switch being determined with reference to the duty cycle of the secondary side switch (S3).

Abstract: A power converter includes a DC power source, a transformer having a first winding, a first MOSFET and a PWM controller at the primary side and a second winding, a drive control unit, a current detection control unit, a comparator and a second MOSFET at the secondary side. The comparator has its input end electrically connected to the current detection control unit and its output end electrically connected to the drive control unit, which is electrically connected to the second MOSFET for synchronous rectification. The second MOSFET is electrically connected to one end of the second winding, having a body diode built therein. The second winding and the second MOSFET constitute a combination circuit electrically connected to a load that has a capacitor electrically connected thereto in a parallel manner. By means of the aforesaid arrangement, conduction loss at a low load is minimized, thereby improving the efficiency at a low load.

Abstract: Consistent with an example embodiment, there is a method of controlling a synchronous rectifier having an input signal having oscillations therein and a switch which is switchable between an open state and a closed state. The method comprises filtering the input signal to produce a filtered signal, comparing the filtered signal with a reference value, and opening the switch in response to the comparison, in which the filtering is active filtering. The active filtering may be based on determination of the peaks (positive and/or negative) of the signal, either directly, including a quarter period offset, or including decay—or a combination of the above; alternatively, the active filtering may be based on the a smoothing functions such as a switched low-pass filter or a short time integrator.

Abstract: A power conversion apparatus includes main circuits, in which switching elements are connected in parallel with diodes, respectively. An auxiliary circuit, which is formed of a series-connected second switching element and a capacitor, is connected in parallel with the diode operating as a freewheeling diode. The switching element of the main circuit, which is opposite to the auxiliary circuit, is set to turn on at a reference time. The second switching element of the auxiliary circuit is set to turn on in advance of the reference time by an interval of a discharging time period of the capacitor in a dead time period.

Abstract: A resonant converter equipped with a phase shifting output circuit includes a resonant circuit to receive input power and regulate to become at least one resonant power, a switch unit to switch an ON period for the input power to pass through the resonant circuit and a power transformation circuit to regulate the resonant power and output a transformed power. The resonant converter further has a primary output circuit and at least one secondary output circuit. The primary output circuit regulates the transformed power to become a primary output power. A resonant control unit captures a feedback signal from the primary output circuit and generates a resonant control signal. A phase shifting control unit receives the resonant control signal and regulate to become a phase shifting driving signal. The secondary output circuit is controlled by the phase shifting driving signal and provides a secondary output power.

Abstract: A synchronous rectification circuit includes a transformer receiving an input voltage at a primary side and outputting an output voltage at a secondary side and a controller arranged and programmed to operate independently from the input and output voltages. The controller preferably outputs control signals to switching logic devices, the switching logic devices being arranged to output timing signals to drive individual synchronous rectifiers included in the secondary side of the transformer. The synchronous rectification circuit includes at least one logic gate which receives the control signals output from the controller and supplies clock signals to the switching logic devices, the clock signals being generated by the at least one logic gate based on the control signal and driving devices arranged to receive the timing signals from a respective one of the switching logic devices, the driving devices driving the synchronous rectifiers in accordance with the timing signals.

Abstract: A predictive synchronous rectification controller for controlling at least one synchronous rectification switch is provided. The synchronous rectification controller has a ramp generator, a peak sampling unit, and an output control unit. The ramp generator receives a synchronous signal and generates a ramp signal accordingly. The peak sampling unit generates a predicted reference voltage signal by retrieving a peak voltage of the ramp signal. The output control unit compares the ramp signal with the predicted reference voltage signal to generate a synchronous rectification control signal to control a conducting state of the switch.

Abstract: A power supply device includes a main unit and a power switching module. The main unit includes a primary circuit board, a transformer including a primary and a secondary coil, a primary-side circuit and a secondary-side circuit. The power switching module includes a separate PCB formed with at least two connection pads and two conductive tracks, and at least one power switching element disposed on the PCB and having two terminals respectively connected to the two connection pads through the two conductive tracks. The power switching module is in the form of a separate PCB that is electrically connected to the primary- or secondary-side circuits through the two connection pads.

Abstract: A power circuit is applicable to a Direct Current (DC) to DC converter. The power circuit includes a gate driver circuit and a High Electron Mobility Transistor (HEMT). The gate driver circuit functions as a Sigmoid (S) function and controls a gate and a source of the HEMT with a cross voltage of the sigmoid (S) type function. Accordingly, an overall characteristic curve of the HEMT and the gate driver circuit is like a characteristic curve of a single rectifier diode, so as to achieve a rectifying, freewheeling, or reversing effect. In addition, since an energy loss is low when the HEMT is conducted, the energy loss of the whole power circuit is much less than that of a conventional diode.

Abstract: A switching power-supply apparatus includes a first converter 3, a second converter 4, an output smoothing capacitor Co1, a series resonance circuit 1 and a control circuit 11. The first converter 3, in which switching elements Q11 and Q12 are connected to both ends of a direct-current power-supply Vin in series, and a capacitor Ci1 and a primary winding Np1 of a transformer T1 including an auxiliary winding Na1 are connected to both ends of the switching element Q12 in series, includes diodes D11 and D12 that rectify voltages generated in secondary windings Ns11 and Ns12 of the transformer T1. The second converter 4, in which switching elements Q21 and Q22 are connected to the both ends of the direct-current power-supply Vin in series, and a capacitor Ci12 and a primary winding Np2 of a transformer T2 are connected to both ends of the switching element Q22 in series, includes diodes D21 and D22 that rectify voltages generated in secondary windings Ns21 and Ns22 of the transformer T2.

Abstract: Disclosed is a light load control circuit and the method accordingly where the synchronous rectification is latched off when the light load condition is detected for several successive cycles.

Abstract: An AC/DC power converter has an AC input and a DC output, with an input rectifier circuit coupled to the AC input. The input rectifier circuit includes a passive half-bridge rectifier circuit functional to provide passive rectification of an AC input power sign and at least one current shaper circuit. The current shaper circuit includes an input inductor coupled between the AC input and a switch node in the input active rectifier circuit. The input current shaper circuit is functional to shape an AC input current signal associated with an AC input power signal to a substantially sinusoidal current signal. A bulk capacitor circuit is coupled to the input active rectifier circuit. A DC/AC converter circuit is coupled to the bulk capacitor circuit. A resonant circuit is coupled to the DC/AC converter circuit and an output rectifier circuit may be coupled between the resonant circuit and the DC output.

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: A driver for a switch, method of driving a switch, and a power converter employing the same. The driver for the switch includes a first driver switch coupled to a terminal of the switch. The driver also includes a second driver switch inverted with respect to the first driver switch and coupled to another terminal of the switch, wherein the first and second driver switches are configured to provide a drive signal to a control terminal of the switch.

Abstract: According to one embodiment, a power conversion apparatus determines a peak value of circuit current in each pulse cycle, from a corrected output voltage value by subtracting a predetermined reference voltage from an output voltage detected by the output voltage detector, and an input voltage detected by the input voltage detector. The pulse signal output unit outputs a pulse signal to the first switch when the polarity of input voltage is positive, and outputs a pulse signal to the second switch when the polarity of input voltage is negative. A pulse signal turns on in synchronization with a clock signal input from the oscillator, and is kept on until the circuit current detected by the circuit current detector reaches the peak value. A pulse signal turns off when the circuit current reaches the peak value, and turns on again in synchronization with the next clock signal.

Abstract: Methods, systems, and devices are described for both power and control signal transmission through a single coupled inductor. A current driver generates a cyclical current signal on a primary winding of a coupled inductor, to induce a voltage signal at the secondary winding corresponding to the cyclical current signal. A rectifier module is coupled with the secondary winding and configured to rectify the signal induced at the secondary winding. A control timing signal module is coupled with the primary winding and configured to induce voltage pulses on the secondary winding, the induced voltage pulses having an insubstantial impact on the output of the rectifier module. A switching module coupled with the secondary winding is configured to receive the voltage pulses and control a switching signal for a power switch coupled with the output of the rectifier and provide power to a load coupled with the output of the rectifier.

Abstract: A solid-state lighting system comprises a plurality of light-emitting devices (e.g., light-emitting diodes) and an alternating current to direct current (AC-DC) converter that converts AC power to DC power for powering the plurality of light-emitting devices. The AC-DC converter is configured to perform AC-DC conversion directly, without the need for or use of a bridge rectifier or step-down transformer. According to one aspect of the invention, the light-emitting devices of the solid-state lighting system are autonomous and individually powered by a plurality of DC power supplies generated from the DC power produced by the AC-DC converter. According to another aspect, a plurality of phase-offset dimmer control signals are generated based on waveform distortions in a dimming signal produced by a conventional dimmer switch. The phase-offset dimmer control signals are used to individually control the dimming of the light-emitting devices.

Abstract: A pseudo-resonant switching power source device is provided which comprises a primary winding 2a of a transformer 2 and a main MOS-FET 3 connected in series to a DC power source 1, a voltage-resonant capacitor 12 connected in parallel to main MOS-FET 3, a rectification smoother 4 connected to a secondary winding 2b of transformer 2 and having a rectification MOS-FET 51 and a smoothing capacitor 6, a synchronized rectification controller 52 for turning rectification MOS-FET 51 on after turning-off of main MOS-FET 3 and turning rectification MOS-FET 51 off before turning-on of main MOS-FET 3, a pulse width elongation circuit 55 for extending on-pulse width of rectification MOS-FET 51, and a main control circuit 8 for producing main drive signals to turn main MOS-FET 3 off and on with operation frequency responsive to on-pulse width of rectification MOS-FET 51 extended by pulse width elongation circuit 55 to vary operation frequency of main MOS-FET 3 so as to restrain noise by high frequency components in main d

Abstract: A DC to DC converter can include a reverse-blocking semiconductor switch that makes a synchronously rectifying MOSFET become parallel-connected with a capacitor that is connected to a power supply of a controller IC for a conventionally used synchronously rectifying circuit. The reverse-blocking semiconductor switch can be driven either by signals for adjusting a voltage of the capacitor within a permitted range of voltage of the power supply of the controller circuit, or by signals that are determined by a signal obtained from voltage across the MOSFET and the signals for adjusting a voltage of the capacitor within a permitted range of voltage of the power supply of the controller circuit.

Abstract: A drive circuit for a synchronous rectifier, a method of driving a synchronous rectifier and a power converter incorporating the drive circuit or the method. In one embodiment, the drive circuit includes: (1) a first drive circuit stage configured to derive a timing for at least one drive signal from a secondary winding of a transformer coupled to the synchronous rectifier and (2) a second drive circuit stage, coupled to the first drive circuit stage and configured to employ a substantially stable voltage source to provide power for the at least one drive signal and apply the at least one drive signal to at least one control terminal of at least one synchronous rectifier switch in the synchronous rectifier.

Abstract: A circuit for operating a household appliance, wherein the circuit includes a switched-mode power supply for converting the power supply of a public power supply network into direct supply voltage. The circuit also includes a controller that is connected to the switched-mode power supply for being supplied with the direct supply voltage and for controlling processes of the household appliance. An EMC filter is provided to protect the public supply network from interference signals from the household appliance. The EMC filter includes a condenser that is connected between a phase conductor pole and a neutral conductor pole of the public power supply network; a bleeder resistor that is connected in parallel with the condenser; and a switch that can be activated by the controller to connect the condenser and the bleeder resistor to the neutral conductor pole.

Abstract: Methods and circuits for synchronous rectifier control are disclosed herein. In one embodiment, a synchronous rectifier control circuit can include: (i) a first sense circuit to sense a voltage between first and second power terminals of a synchronous rectifier device prior to a turn-on of the device, where a timing of the turn-on of the synchronous rectifier device is adjustable using a first control signal generated from the first sense circuit; (ii) a second sense circuit configured to sense a voltage between the first and second power terminals after a turn-off of the device, where a timing of the turn-off of the device is adjustable using a second control signal generated from the second sense circuit; and (iii) a driver control circuit configured to receive the first and second control signals, and to generate therefrom a gate control signal configured to drive a control terminal of the synchronous rectifier device.

Abstract: A synchronous rectification control device achieves high power conversion efficiency without supplying additional signal to a secondary side from a primary side. An insulated type switching power supply provides such a synchronous rectification control device. An output power is regulated based on a phase difference between two half bridges in the primary side. In the secondary side of the full bridge converter circuit, a center tap is lead out from the secondary windings of a transformer to obtain two symmetrical sections of windings. A device for detecting winding voltage observes winding voltages at terminals of the sections of windings. The synchronous rectification control circuit controls transistors and MOSFETs connected to the secondary windings to make the transistor in the ON or OFF state depending on the current flow in the secondary windings.