Abstract: Various systems and methods for implementing feedback in a switching regulator are disclosed. For example, various current feedback circuits are disclosed that include a current feedback node and a sense node. In addition, the current feedback circuits include an operational amplifier with two inputs. One of the inputs is electrically coupled to a power source via a first resistor, and may further be electrically coupled to a ground by closing a first switch or to the sense node by closing a second switch. The other input is electrically coupled to the ground via a second resistor, and may further be electrically coupled to the sense node by closing a third switch or to the power source by closing a fourth switch. The operational amplifier drives the current feedback node.

Abstract: This invention relates to control techniques and controllers for resonant discontinuous forward power converters (RDFCs). A method of controlling a resonant discontinuous forward converter (RDFC), said converter including a transformer with primary and secondary matched polarity windings and a switch to, in operation, cyclically switch DC power to said primary winding of said transformer, said converter further having a DC output coupled to said secondary winding of said converter, said method comprising: sensing a primary winding signal during an on period of said switch, said primary winding signal representing a current in said primary winding; comparing said sensed primary winding signal with a threshold value; and controlling one or both of an on and off duration of said switch in response to said comparison.

Abstract: A system and method for a bridgeless power supply is disclosed. The bridgeless power supply includes a digital control module that controls a first switch, a second switch, and a transistor, thereby the bridgeless power supply rectifies an alternating current (AC) variable input voltage and regulates a direct current (DC) output voltage. The digital control module applies a first and second control signal to the first and second switches thereby rectifying and regulating the AC variable input voltage. Additionally, the digital control module provides a high frequency and constant duty cycle third control signal to the transistor in series with an output transformer of the bridgeless power supply device, to assure primary-to-secondary isolation.

Abstract: A commutation switch turning-on control switching element is controlled with a voltage generated at a fourth coil (auxiliary coil) of a main transformer and controls application of a control voltage to a control terminal of a commutation switching element. A commutation switch turning-off control switching element is provided which is connected to the control terminal of the commutation switching element and, when the commutation switch turning-off control switching element is turned on, controls a voltage at the control terminal of the commutation switching element to turn off the commutation switching element. A control switching element drive circuit turns on the commutation switch turning-off control switching element at a time when a primary switching element is turned on.

Abstract: A voltage conversion circuit and a switching power supply device achieving both a good response and a low loss of a power supply voltage, wherein a main voltage conversion portion (circuit block) for conversion an AC voltage to a DC voltage, an auxiliary voltage conversion portion for the same conversion but in transit period up to shifting to a stationary state, a voltage limiting portion (Zener diode) for limiting the DC voltage output from the auxiliary voltage conversion portion to a constant limit-voltage, and an output control switch (transistor) connected in the output pass and for switching the pass to conductive or nonconductive possible to apply a higher voltage in between a voltage at the output node and the limit-voltage based on their magnitude relation.

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 first series circuit, connected to both terminals of a direct current power supply Vdc1, in which a primary winding 5a of a transformer T, a reactor L3 and a first switch Q1 are connected in series; a second series circuit, connected to both terminals of the primary winding 5a and the reactor L3, which includes a switch Q2 and a capacitor C3; a smoothing circuit D1, D2, L1, C4; and a control circuit 10 alternately turning on and turning off the switches Q1, Q2. The transformer T includes: a main core 21, formed with a magnetic circuit, on which the primary and secondary windings 5a, 5b are wound with a given gap 23; and a plurality of auxiliary cores 24a, 24b disposed in the given gap 23 with a given distance in a circumferential direction of the primary winding 5a. Further, the reactor L3 is formed of a leakage inductance of the transformer T.

Abstract: A power supply device has first and second terminals, a transformer, a switching element and an auxiliary power supply element. The first and second terminals receive input power having an input voltage. The transformer has a primary winding and a secondary winding. The primary winding has a pair of winding terminals. One of the pair of winding terminals is connected to the first terminal. The switching element is connected between the second terminal and the other of the pair of winding terminals of the primary winding. The auxiliary power supply element feeds electric power to the transformer when the input voltage decreases to or less than a predetermined value. The auxiliary power supply element has a capacitor and a second switching element for storing energy from the primary winding into the first capacitor during a normal operation of the power supply device.

Abstract: A technique for extending the operating range of a flyforward converter to low input voltages. In one aspect, power converter includes a positive input supply rail and a negative input supply rail. A power converter input voltage is to be applied between the positive and negative input supply rails. A flyback energy transfer element having a flyback input winding and a forward energy transfer element having a forward input winding are also included. The flyback and forward input windings are coupled between the positive and negative input supply rails. Voltage control circuitry coupled to the forward energy transfer element is also included to reduce a voltage across the forward input winding, substantially to zero, when the power converter input voltage falls below a first threshold value.

Abstract: An object of the present invention is to lower the voltage applied to the starting resistor of the starting circuit in a switching power supply circuit to reduce the power loss especially when the receiving voltage is high and thereby provide a small and inexpensive switching power supply circuit. According to the present invention, a switching power supply circuit comprises: a DC voltage section having two or more capacitors connected in series; and a PWM control circuit for receiving DC power supply from the DC voltage section and performing switching control on a primary side of a transformer in order for the switching power supply circuit to output a DC voltage of different voltage specifications; wherein the starting resistor for the PWM control circuit is connected to a connection point of the capacitors.

Abstract: A chop-wave control circuit includes a feedback unit, a ramp generation unit, a latchup unit and a voltage transformation unit that is used on a forward transformation circuit which includes at least a main output unit and at least one auxiliary output unit. The feedback unit captures a feedback signal from an output end of the auxiliary output unit to generate a slope regulation signal. The ramp generation unit alters the trigger time sequence of the latchup unit through the slope regulation signal to set an auxiliary flywheel switch ON or OFF. The voltage transformation unit detects potential variations of the latchup unit to set a chop-wave switch ON or OFF. By controlling the auxiliary flywheel switch and the chop-wave switch a power output cycle of the auxiliary output unit can be formed.

Abstract: A power supply device includes: a regulator transformer; a primary switch for selectively supplying a current to the regulator transformer; a control circuit for reducing to 0, following each election made at the primary switch, the minimum value of a current output by the secondary side of the regulator transformer; and a coupling transformer for magnetically coupling routes along which a plurality of loads are connected in parallel to the secondary side of the regulator translator in a direction in which magnetic flux along each of the routes is offset by a current change. In this case, the control circuit increases the maximum value of the output current on the secondary side larger than twice of the target value of the current supplied to the loads.

Abstract: A DC converter includes a time difference detector to detect a time difference between a point around which a main switch provides a minimum voltage after an auxiliary switch turns off and a point at which the main switch turns on, an integrator to integrate the output of the time difference detector, and a first delay circuit to control a turn-on point of the main switch according to the output of the integrator and the output of the time difference detector. The first delay circuit operates to minimize the output of the time difference detector according to the output of the integrator and controls a turn-on point of the main switch in a pulse-by-pulse manner according to a pulse-by-pulse control signal based on the output of the time difference detector.

Abstract: In a post regulation control circuit mainly used in a switching power supply with several sets of outputs, the circuit adopts leading edge synchronization and conduction time regulation for the control, and a leading edge of the waveform of an input voltage of a detected secondary inductor generates a sync signal to reset a ramp generator to produce a stable continuous ramp signal, and compares with a feedback voltage to generate a power conduction signal corresponding to a stable output voltage. After the power conduction signal is cut off, a flywheel conduction signal in an inverted phase is produced. The two signals separately have an output terminal for driving two power switches of power conduction and flywheel conduction. The circuit applicable for various AC or DC step-down regulators gives a stable regulation control for the switching power supply with several alternating outputs.

Abstract: A voltage stabilizer circuit of forward converter is disclosed to include a transformer, a first switch, a rectifier, an error amplifier, a control circuit, and a driving circuit. The control circuit outputs a regulation signal that controls turn-on time of the first switch, keeping the output of the load voltage at a stable level.

Abstract: A DC/DC converter includes: a boost converter that boosts an input voltage in accordance with a first control signal; an insulated converter that converts an output of the boost converter in accordance with a second control signal; a current sensor that detects an output current of the insulated converter; a first controller that generates the first control signal based on an error between the output current detected by the current sensor and a first threshold value; and a second controller that generates the second control signal based on an error between the output current detected by the current sensor and a second threshold value that is larger than the first threshold value.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. In one embodiment, a power supply regulator includes a power transistor having first, second, third and fourth terminals. A control circuit is included, which is coupled to the third and fourth terminals of the power transistor. The power transistor is configured to switch a current between the first and second terminals in response a control signal received from the control circuit at the third terminal. A voltage between the fourth and second terminals of the power transistor is substantially proportional to a current flowing between the first and second terminals when a voltage between the first and second terminals is less than a pinch off voltage. The voltage between the fourth and second terminals of the power transistor is substantially constant and less than the voltage between the first and second terminals when the voltage between the first and second terminals is greater than the pinch off voltage.

Abstract: The present invention is directed to a power supply unit that provides large power supply to the load. The voltage detector 51 generates a voltage detection signal by detecting the voltage generated at the output terminals 21, 22. The current detector 52 generates a current detection signal by detecting the current that runs through the transformer 3. The control circuit 9 uses the voltage detection signal and the current detection signal and thereby controls, in at least one of the first and second switching elements SW1, SW2, the timing with which the switching element is turned ON and the length of time that the switching element remains ON, such that the transformer current flows in a continuous mode.

Abstract: An apparatus (54) is provided for preventing cross conduction in a synchronous rectifier of a DC-DC converter (10). The DC-DC converter has an input MOSFET switch (26) coupled to primary windings (22) of an isolation transformer (20), an output MOSFET switch (30) coupled to secondary windings (24) of the isolation transformer, and a complementary output MOSFET switch (34) coupled to an output terminal (14). A synchronous rectifier timing circuit (54) comprises a first timing output signal circuit (62) responsive to a pulse width modulated signal for providing first and second timing output signals (55, 56) that switches low at time t1 and high at time t4 to control the input MOSFET switch and output MOSFET switch, respectively, and a second timing output signal circuit (64) responsive to the pulse width modulated signal for providing a third timing output signal (58) that switches high at time t2 and low at time t3 to control the complementary output MOSFET switch.

Abstract: A method for driving a fluorescent lamp and an inverter circuit for performing the same are used to reduce an amount of electromagnetic interference (EMI) generated by a transformer and an instantaneous loading of a DC voltage source. The inverter circuit comprises a DC square wave voltage source, a bridge DC/AC converter, a transformer, a feedback control unit and a voltage control circuit wherein the voltage control circuit is coupled to the DC voltage source, the bridge DC/AC converter and the feedback control unit. The voltage control circuit is used to convert DC voltage provided by the DC voltage source into a two-level DC square wave, which in turn converts the two-level DC square wave into an AC quasi-sine wave to drive the fluorescent lamp through the bridge DC/AC converter and the transformer. The feedback control unit generates signals to control the voltage control circuit and the bridge DC/AC converter.

Abstract: A switching power supply apparatus has a switching device control circuit for performing overcurrent protection by controlling switching-on/off of a switching device, connected serially to a primary winding of a transformer, so as to make a voltage output from a rectifying and smoothing circuit, connected to a secondary winding of the transformer, have a specific value, and switching off the switching device when the electric current flowing through the switching device exceeds a value as an overcurrent detection point.

Abstract: Provided is a direct-current converter which can reduce power consumption at light load by reducing switching losses of a main switch. The direct-current converter is provided with: a first serial circuit which is connected to both ends of a direct current power supply Vdc1 and in which a primary winding P of a transformer T and a main switch Q1 are serially connected to each other; a second serial circuit which is connected both ends of the primary winding P of the transformer T and in which an auxiliary switch Q2 and a snubber capacitor C2 are serially connected to each other; rectifying/smoothing circuits D5, D6, L1 and C5 which rectify and smooth a voltage generated in a secondary winding S of the transformer T by energy supplied from the primary winding P of the transformer T when the main switch Q1 is turned on; and a control circuit 10 which turns on/off the main switch Q1 and the auxiliary switch Q2 alternately using a signal with predetermined switching frequency.

Abstract: A closed loop power converter circuit of a UPS or other power supply includes a pulse width modulator circuit in a forward path of the closed loop power circuit. A compensation circuit provides pulse width commands to the pulse width modulator at a first rate. A feedback circuit digitally filters samples of an output of the closed loop power converter at a second rate greater the first rate and that provides the filtered samples to the compensation circuit. In some embodiments, the compensation circuit may be operative to compensate for the phase lag associated with a low pass output filter.

Abstract: A switching converter in which an input voltage can be switched by means of at least one controlled switch to at least one primary winding of a transformer, with a control circuit for controlling the switch, to which control circuit a regulating signal in the sense of regulating at least one output voltage is sent, wherein the power supply of the control circuit takes place via the forward voltage of an auxiliary winding of the transformer, a rectifier, a capacitor and a series regulator, on the one hand, and, on the other hand, starting from the input voltage, via a current path and a storage capacitor, and the off-state voltage of an auxiliary winding, which is rectified by means of a rectifier, is additionally sent to the control circuit for power supply, wherein the rectified off-state voltage is used during the operation for supplying the control circuit as long as it has a sufficient voltage level.

Abstract: A controller controlling the output current at the primary side of a power supply is provided. A waveform detector generates a current-waveform signal. A second control circuit generates an oscillation signal for determining the switching frequency of a switching signal. An integrator generates an integrated signal by integrating an average current signal with a time signal. The average current signal is generated in response to the current-waveform signal. The time signal is generated in accordance with said oscillation signal. The time constant of the integrator is correlated with the switching period of the switching signal, therefore the integrated signal is proportional to the output current. A first control circuit generates the switching signal in correlated with the integrated signal, the oscillation signal and a reference voltage. Wherein the first control circuit controls the pulse width of the switching signal. Therefore, the output current of the power supply can be regulated.

Abstract: Provided is an inverter circuit including a rectification and filter circuit and an inverter driver circuit interconnected the rectification and filter circuit and a load. The inverter driver circuit comprises a second controller for receiving light adjustment cycle signals and outputting electrical conduction cycle signals wherein the second controller is either electrically connected to a power source or electrically connected to the rectification and filter circuit for obtaining a wave current, and an electrical conduction of the electrical conduction cycle signals depends on input on/off of the wave current at the second controller; and a driver operates in response to electrical conduction cycle signals and on/off of DC. A flashing effect is produced on the load and thus a power factor correction effect is produced without power factor corrector being involved.

Abstract: The present invention includes multiple power converters for driving one or more loads via an input power source, AC or DC. A first switching power converter has first one or more windings coupled to an input power source, and a second switching power converter having second one or more windings coupled to one or more loads. A magnetic device comprising a single integrated magnetic core couples the first one or more windings to the second one or more windings for reducing switching loss.

Abstract: A power supply device and a single photo-coupler control circuit thereof are provided. The power supply device includes a single photo-coupler control circuit, a main converter and an auxiliary converter. The main converter connects to an output load. The auxiliary converter connects in parallel with the main converter. The single photo-coupler control circuit, also connected to the output load, monitors the status of the power supply device and controls the main converter and the auxiliary converter accordingly. The single photo-coupler control circuit only has one photo-coupler. The main converter and the auxiliary converter together provide a first output to the output load when the power supply device works in a normal mode. The main converter is turned off so that only the auxiliary converter provides a second output to the output load when the power supply device works in a standby mode.

Abstract: In a lighting apparatus for a discharge lamp, a mask signal against a re-arc voltage is correctly generated to detect a lamp voltage accurately in view of a support to high frequency lighting such that the detection of the lamp voltage is not affected by the re-arc voltage. The lighting apparatus for the discharge lamp comprises a DC-AC converter for receiving an input voltage from a DC power supply to convert the input voltage to an AC voltage; detecting means for detecting a lamp voltage associated with a discharge lamp or a lamp voltage and a lamp current; and a signal generator circuit for generating a mask signal for excluding a re-arc voltage, which occurs at the time the polarity is inverted, from items to be detected, in the event of a detection of the lamp voltage. The signal generator circuit detects the lamp voltage or lamp current or a voltage at an output stage of the DC-AC converter to correctly capture a polarity inversion timing to generate a mask signal against the re-arc voltage.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A switching power source apparatus has a series circuit connected to both ends of a DC power source Vdc1 and having a reactor L3, a primary winding 5a of a transformer T, and a switch Q1, a series circuit connected to both ends of the primary winding and having an auxiliary switch Q2 and a clamp capacitor C3, a saturable reactor SL1 connected in parallel with the primary winding, a rectifying-smoothing circuit D1, D2, L1, C4 for rectifying and smoothing a voltage generated on a secondary winding 5b, and a control circuit 10 for alternately turning on/off the switches Q1 and Q2 and turning off the switch Q2 if a current of the switch Q2 increases due to saturation of the saturable reactor SL1. The reactor L3 is made of leakage inductance between the primary and secondary windings.

Abstract: In one embodiment, an apparatus includes a transformer having a primary winding and a secondary winding and a switching circuit to facilitate a periodic application of an input voltage to the primary winding. The switching circuit includes an active switch and a capacitor commonly coupled to the primary winding. In one embodiment, the apparatus further includes a synchronous rectification circuit coupled to the secondary winding to generate a rectified signal, an output filter coupled to the synchronous rectification circuit to provide an output voltage in response to the rectified signal, and a control circuit coupled to the output filter to receive the output voltage and coupled in a switching control relationship with the active switch and the synchronous rectification circuit.

Abstract: A circuit is provided for converting power from an AC power source to DC power. The circuit including bi-directional switches capable of conducting and blocking a current flow in both directions. One or more control switches are coupled to a bi-directional switch to enable and disable the current flow through the bi-directional switch, the control switches are controlled by a signal voltage to turn a bi-directional switch ON by discharging a threshold voltage on one of the bi-directional switch gates and turning a bi-directional switch OFF when the threshold voltage is not discharged by the control switches. Additionally, the circuit includes a transformer having one or more primary windings and a secondary winding, each primary winding being coupled to one of the bi-directional switch sources. The current flow through the primary winding is disabled when the current flow through the corresponding bi-directional switch source is disabled.

Abstract: The present invention discloses a power supply device for outputting a stable programmable power supply, which comprises a transformer disposed at a DC output end of the power supply device, and a clamp circuit connected to a secondary current of the transformer. Since the clamp circuit is disposed on the secondary current of the transformer, therefore it does not require a high DC voltage to drive the clamp circuit. The clamp circuit can release the high voltage produced when the metal oxide semiconductor field effect transistor (MOSFET) is off, and thus reducing the high voltage borne by the MOSFET to enhance the reliability of the MOSFET. Additionally, the present invention can prevent the transformer from being saturated due to magnetic leakage, inductance, and stored energies released or eliminated from the transformer.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. In one embodiment, a power supply regulator includes a power transistor having first, second, third and fourth terminals. A control circuit is included, which is coupled to the third and fourth terminals of the power transistor. The power transistor is configured to switch a current between the first and second terminals in response a control signal received from the control circuit at the third terminal. A voltage between the fourth and second terminals of the power transistor is substantially proportional to a current flowing between the first and second terminals when a voltage between the first and second terminals is less than a pinch off voltage. The voltage between the fourth and second terminals of the power transistor is substantially constant and less than the voltage between the first and second terminals when the voltage between the first and second terminals is greater than the pinch off voltage.

Abstract: A power factor correction circuit structure is described. The power factor correction circuit comprises a series connection of a first winding, a diode, an inductor and a first capacitor. The polarity of the first winding is opposite to that of the primary winding. A second capacitor is connected to the primary winding to control the primary winding and build a voltage across the first capacitor. This voltage is transferred to the first winding through the transformer to boost the first capacitor voltage and improve the power factor.

Abstract: In a switching DC/DC converter using an insulating transformer Tr, a primary coil and a secondary coil of the transformer Tr, an input choke coil L1, and an output choke coil L3 are wound around a common core and are formed into a single component. A primary circuit of the transformer Tr includes a switching device Q1 connected in series with the primary coil, an input choke coil L1 connected across the terminals of the primary coil, and a series circuit of a clamp capacitor C1 and a switching device Q1? which are connected across the terminals of the primary coil. A secondary circuit of the transformer Tr includes rectifying switching devices Q2 and Q2? connected to the secondary coil, the output choke coil L3, and an output smoothing capacitor C0. Further, a series circuit of the switching device Q1? and the clamp capacitor C1 may be connected across the terminals of the switching device Q1.

Abstract: A power converter having a primary circuit (e.g. full bridge) and a secondary circuit (e.g. current doubler) has switches in the secondary circuit that are controlled by a drive circuit. The drive circuit is connected to a swing node in the primary circuit, and is powered by the primary circuit. The drive circuit has an isolation device such as a transformer to provide electrical isolation between the primary circuit and secondary circuit. The drive circuit provides a current source for driving the secondary switch gates, thereby reducing power consumption. The present drive circuit provides clean gate drive signals without noise and oscillations. The drive circuits of the invention are simple, and require only a few components.

Abstract: A power device such as a forward converter employing a main switch in series with a power transformer coupling an input, primary circuit and an output, secondary circuit has its transformer reset from a reset capacitor that is switched. Switching of the reset capacitor is effected by a reset switch, preferably a MOSFET, the control electrode of which is driven from a reset winding on the power transformer. Current flow between the reset capacitor and the primary winding resets the transformer. The capacitor can be chosen such that flux density in the transformer core is substantially symmetrical about zero. Leakage and magnetizing conductance energy is recycled. Large spikes are not produced across the main switch.

Abstract: In a switching power supply device, the operating voltage is supplied to the power-factor improvement control circuit when the switching power supply device is operating under normal operating load. Thereby, the booster chopper circuit is controlled by the power-factor improvement control circuit so as to improve the power factor of the device. By contrast, during the non-oscillation period while the switching control circuit is in the intermittent oscillation mode when the power consumption is small, the voltage induced in the auxiliary winding drops. Accordingly, the voltage of the auxiliary power supply also drops. Furthermore, when the driving voltage to be supplied to the power-factor improvement control circuit is reduced below the operating voltage thereof by the voltage reduction circuit, the power-factor improvement control circuit stops functioning, thereby reducing power consumption accordingly.

Abstract: A method for operating a switch, which is connected in series with a primary coil of a transformer in a free-running switch mode power supply, includes the provision of a modulation signal and the provision of a drive signal for the switch. The drive signal includes a recurrent pulse sequence which has at least one first switching-on pulse with a first pulse duration and at least one second switching-on pulse with a second pulse duration, and with the pulse duration of at least one of the switching-on pulses being modulated by the modulation signal within a range of valves which is predetermined by the control signal.

Abstract: An induction heating device includes a plurality of induction coils connected to a single high-frequency power source and each being able to be ON/OFF controlled by a switch. A current is selectively fed only to desired part of the induction coils or to all of the induction coils connected in parallel. The coils are driven by a current fed thereto at the same time in the same phase. The device may include inverters for controlling power to be fed coil by coil. The device is free from interference and irregular heating and can readily cope with a change in a heating range while controlling power coil by coil.

Abstract: The present invention provides a power supply apparatus with a plurality of digital control units. Each digital control unit is used to control an independent output terminal for outputting a stable output voltage. The output voltage is not fed back to the primary side of the transformer.

Abstract: An apparatus for reducing the power consumption of a PFC-PWM power converter is described. The apparatus includes a control terminal used to detect a line-input voltage and to control a PFC signal and a PWM signal. The apparatus further includes a PFC power-manager and a PWM power-manager. The PFC power-manager of the PFC controller determines a PFC-reference voltage for an error amplifier of the PFC controller. The PFC-reference voltage is generated in response to the voltage at the control terminal. The PFC power-manager will disable the PFC signal whenever the voltage at the control terminal drops below a low-voltage threshold voltage. The PWM power-manager will disable the PWM signal whenever the voltage at the control terminal drops below a programmable threshold voltage. Furthermore, the PWM power-manager will pull the voltage at the control terminal low to disable the PFC circuitry during light-load and zero-load conditions.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. In one embodiment, a power supply regulator includes a power transistor having first, second, third and fourth terminals. A control circuit is included, which is coupled to the third and fourth terminals of the power transistor. The power transistor is configured to switch a current between the first and second terminals in response a control signal received from the control circuit at the third terminal. A voltage between the fourth and second terminals of the power transistor is substantially proportional to a current flowing between the first and second terminals when a voltage between the first and second terminals is less than a pinch off voltage. The voltage between the fourth and second terminals of the power transistor is substantially constant and less than the voltage between the first and second terminals when the voltage between the first and second terminals is greater than the pinch off voltage.

Abstract: To demagnetize a transformer (TR) in a single-ended forward DC/DC converter with self-driven synchronized rectifiers (V1, V2) connected across the secondary winding (N2) of the transformer (TR), a diode (D1) is connected in series with a capacitor (C1) across the primary winding (N1) of the transformer. The diode (D1) transfers magnetization energy stored in the transformer to the capacitor (C1) every time a primary switch (V3) of the converter is turned off. To ensure optimum efficiency of the synchronized rectifiers, a discharging circuit is connected to the capacitor (C1) for discharging the magnetization energy stored therein by drawing a DC current (I) from the capacitor (C1) in response to varying input DC voltage such that complete demagnetization of the transformer (TR) always is attained just before turn-on of the primary switch (V3).

Abstract: A common mode noise cancellation circuit eliminates common mode noise generated by one or more high-frequency switching devices. A common mode noise waveform generated by the one or ore switching devices is capacitively coupled from the primary winding to the first secondary winding of a transformer. A set of cancellation secondary windings generates a common mode cancellation waveform, and cancels the common mode noise waveform because the common mode cancellation waveform is approximately equal in amplitude and opposite in phase to the common mode noise waveform. A triac control circuit receives an AC input and determines whether the AC input is within a range where multiplying of the DC voltage is implemented. If the triac control circuit determines the AC input is within the range, the triac control circuit transmits a triac firing signal to the triac circuit. The triac circuit charges a capacitor bank to multiply the DC voltage.

Abstract: A switching power supply circuit ready for worldwide use is disclosed which suppresses a variation of a pulse voltage to be fed back when the alternating-current input varies. The switching power supply circuit includes a composite resonance type converter of a switching frequency control scheme wherein a voltage resonance pulse voltage generated in a primary side voltage resonance converter is fed back to a rectification diode through a high speed diode and an inductance or a transformer. An active clamp circuit is provided on the primary side to clamp the voltage resonance pulse voltage.

Abstract: An induction heating device includes a plurality of induction coils connected to a single high-frequency power source and each being able to be ON/OFF control led by a switch. A current is selectively fed only to desired part of the induction coils or to all of the induction coils connected in parallel. The coils are driven by a current fed thereto at the same time in the same phase. The device may include inverters for controlling power to be fed coil by coil. The device is free from interference and irregular heating and can readily cope with a change in a heating range while controlling power coil by coil.