Abstract: A control circuit for use in a power converter in one aspect limits the magnetic flux in a transformer of a switching power converter. A first controlled current source has a first current that is substantially directly proportional to an input voltage to be applied to a winding of the transformer. A second controlled current source has a second current that is substantially directly proportional to a reset voltage to be applied to the winding of the transformer. A first switch is adapted to charge an integrating capacitor with the first current while the input voltage is applied to the winding of the transformer. A second switch is adapted to discharge the integrating capacitor with the second current when the reset voltage is applied to the winding of the transformer. A third switch is adapted to remove and to prevent application of the input voltage to the winding of the transformer.

Abstract: The switching power supply unit includes: a transformer having a primary winding and two secondary windings; and a rectifying-smoothing circuit having two rectifying elements, three choke coils and a capacitive element. A first rectifying element is between a junction of ends of the first secondary winding and the second choke coil, and one end of the capacitive element. A second rectifying element is between a junction of ends of the second secondary winding and the third choke coil, and the one end of the capacitive element. The other end of the first secondary winding and the other end of second secondary winding are connected to the one end of the first choke coil. The other end of the first choke coil, the other end of the second choke coil, and the other end of the third choke coil are connected to the other end of the capacitive element.

Abstract: One embodiment of the invention relates to a power apparatus. The power apparatus includes a power converter configured to convert an input voltage to an output voltage for providing power at an output thereof to which a load is connectable. The converter can include an isolation barrier configured to electrically isolate the output and the load from an input source that provides the input voltage. The system also includes a control loop that includes indirect sense circuitry configured to indirectly derive an indication of at least one of output current and output power of the converter. The control loop is configured to control output current or output power based on the indirectly derived indication of output current or output power, respectively.

Abstract: A single-board power supply structure and a method for providing a power supply are provided. An operational processor sends control signals capable of controlling the output of the power supply to a DC/DC converter. The DC/DC converter converts a received bus voltage into a required power supply voltage according to the received control signals. The operational processor may further monitor the output of the power supply and report the monitored result to a connected upper-layer machine, and may also control the sequence of a plurality of the outputs of the power supply converted by the DC/DC converter by controlling the time for sending the control signals. The structure and the method provided by the present invention can both uniformly, timely, and effectively monitor the output of the single-board power supply.

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: To detect a peak time of an exciting current of a transformer, a primary current corresponding to the peak time, or a variation time of the primary voltage, and to switch a switch after expiration of a predetermined period from the peak time, after the peak time occurs. A control apparatus 1 is applied to a power conversion circuit 2 which includes a switch circuit 23 including one switch or a plurality of switches and a transformer 21. The control apparatus includes: an output voltage detector 11 detecting a value of an output voltage of the power conversion circuit; an exciting current peak time generator 12 detecting a peak time of an exciting current of the transformer; a timing generator 13 generating a switching timing of the one switch or the plurality of switches. The timing generator 13 generates the switching timing of the one switch or the plurality of switches on the basis of the output voltage and the peak time.

Abstract: A self-coupled transformer boostbuck circuit includes a first transformer having a first winding, a second winding and a third winding, a first switch having a first voltage output at its one end, a second switch, a second transformer, a third switch having a second voltage output at its one end, a fourth switch, a fifth switch having a third voltage output at its one end, and a sixth switch.

Abstract: A power supplying device includes: an output transformer including first and second output coils for generating first intermediate voltages from an input voltage; a voltage adjusting transformer including primary and secondary coils; a first rectifying-and-filtering circuit connected to the first output coil for generating a first output voltage from the first intermediate voltage obtained from the first output coil; the primary coil being connected in parallel to the first output coil, the secondary coil being connected in series to the second output coil and being coupled to the primary coil for generating a second intermediate voltage from the first intermediate voltage obtained from the first output coil; and a second rectifying-and-filtering circuit connected to the secondary coil for generating a second output voltage from a combined voltage combining the second intermediate voltage obtained from the secondary coil with the first intermediate voltage obtained from the second output coil.

Abstract: An isolated DC-DC converter includes a transformer, a main switch, an active clamp circuit and a control unit. The transformer has a primary winding. The main switch and the active clamp circuit are connected to the primary winding. The active clamp circuit has an auxiliary switch and a clamp capacitor connected in series. The control unit is provided for controlling the main switch and the auxiliary switch. The control unit performs a soft start operation of the converter before a normal operation. The control unit performs anti-saturation control before starting the soft start operation. The anti-saturation control includes an act of controlling the main switch and the auxiliary switch so that the auxiliary switch performs ON-OFF operation with the main switch kept OFF until voltage of the clamp capacitor drops below a level at which the transformer is to be magnetically saturated after starting the soft start operation.

Abstract: An integrated circuit is disclosed that integrates a low current, high speed optical receiver with the primary side control functions of the power supply. This is further combined with an optical emitter to create a single component for feedback and control, providing improved performance and manufacturing. A method of providing feedback for the power supply using such an integrated optically coupled control circuit is also disclosed.

Abstract: A DC converter includes: a transformer (T1) including a primary winding (P1) and a secondary winding (S1); a series resonant circuit in which a current resonant reactor (Lr), the primary winding (P1) of the transformer, and a current resonant capacitor (Cri) are connected in series; conversion circuits (Q1, Q2) for converting a DC voltage of a DC power supply (Vin) into a rectangular-wave voltage, so as to output the rectangular-wave voltage to the series resonant circuit; and a rectifier smoothing circuit (D3, D4, Co) for rectifying and smoothing a voltage generated at the secondary winding (S1) of the transformer, so as to output a DC output voltage to a load, wherein a capacitive element (Cr) including a capacitive component corresponding to a floating capacitance (Cp) equivalently present between the primary winding of the transformer was connected to the current resonant reactor (Lr) in parallel.

Abstract: An isolated switching power supply device includes a main transformer having a primary coil on a primary circuit side and a secondary coil on a secondary circuit side. On the primary circuit side are disposed an input smoothing capacitor, a switching control circuit, a high-side driver, a low-side power switch, a high-side power switch, capacitors, and edge signal-generating circuits. A symmetrical control half bridge converter is thus provided. The secondary circuit side has a voltage clamping circuit including a clamp capacitor, a clamp switch and a diode.

Abstract: A single-stage isolated high power factor AC/DC converter with a leakage inductor energy recovery function includes a buck-boost circuit, for step-down or step-down a power supply; a transformer, electrically connected to the buck-boost circuit, for transforming the stepped-down or stepped-up power supply; a switch, electrically connected to the buck-boost circuit; an input capacitor, electrically connected to the buck-boost circuit; and an output circuit, for outputting the power supply transformed by the transformer. When the switch is cut off, the buck-boost circuit provides an energy recovery path to return energy stored in a leakage inductor of the transformer to the input capacitor. The energy stored in the leakage inductor of the transformer in a flyback converter or a forward converter is returned to the input capacitor through the energy recovery path. The problem caused by the leakage inductor of the transformer is solved without using any additional element.

Abstract: A switching regulator. A pulse width modulation (PWM) unit comprises an output stage and generates a PWM driving signal to control the output stage, such that an inductor delivers an inductor current signal to the load, and a slope compensation unit outputs a slope compensation signal with a compensation slope proportional to a falling slope of the inductor current signal to the PWM unit according to the inductor current signal.

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 transformer signal, said transformer signal representing a voltage across a winding of said transformer or a resonant current in a winding of said transformer; calculating a resonance period of said RDFC from said sensed transformer signal; and controlling an off duration of said switch in response to said calculated resonance period such that a sub-harmonic oscillation in said resonant voltage across said primary winding is reduced.

Abstract: A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current.

Abstract: A system and method for operating power supplies. A method comprises altering a current sense (CS) signal, turning off a switch of the converter in response to a determining that the CS signal is greater than or equal to a first threshold, and leaving on the switch of the converter in response to a determining that the CS signal is less than the first threshold.

Abstract: A power supply (V1) for an electrical device comprising a transformer (X1) having primary and secondary windings. The primary winding is connectable to an AC voltage supply and circuitry on the secondary side is arranged to provide a DC output voltage for the electrical device. The power supply also comprises a switch (111—transistors Q1 & Q2) between the primary winding of the transformer and the AC supply, and a rectifier (Diode D6) for rectifying the AC voltage. The switch is arranged to switch on at some point as the rectified AC voltage increases, once it has reached a non-zero value, thereby providing a current flow through the primary winding and hence through the secondary winding when the switch (111—transistors Q1 & Q2) is switched off. The switch is further arranged to switch off before the rectified AC voltage starts to increase again.

Abstract: There is provided a power supply unit, comprising: a converter transformer; a first low voltage generation unit to generate a first voltage on a secondary side of the converter transformer and output the first voltage; a first controller that controls an activation state of a primary side of the converter transformer based on the first voltage; an inactivation unit to inactivate operation of the first controller based on the first voltage to let the first low voltage generation unit to suspend output of the first voltage; a high voltage supply unit to output a high voltage higher than the first voltage by using the first voltage; a detection unit to detect an anomalous state concerning output of the high voltage of the high voltage supply unit. The high voltage supply unit inactivates the operation of the first controller through the inactivation unit when the anomalous state is detected.

Abstract: Provided is a DC-DC converter that can reduce losses. Ein and C1 are serially connected. Q1 and Q2 are serially connected so that antiparallel diodes thereof face the same direction. A terminal of C1 that is not connected to Ein and a terminal of Q2 that is not connected to Q1 are connected. A terminal of Ein that is not connected to C1 and a terminal of Q1 that is not connected to Q2 are connected. A coil N1 of T is connected between a connection point of Ein and C1 and a connection point of Q1 and Q2. Among a pair of terminals of a coil N2, a terminal having the same polarity as a terminal the coil N1 that is connected to Ein is connected to the connection point of C1 and Q2 through D1 and the other terminal is connected to the connection point of Ein and C1. A coil N3 is connected to a smoothing circuit through a rectification circuit. The direction of D1 is set in such a manner that energy can be transferred to C1 from the coil N2 when Q1 is in a conduction state.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. An example power supply control element includes a power transistor that has first and second main terminals, a control terminal and a tap terminal. A control circuit is coupled to the control terminal. The tap terminal and the second main terminal of the power transistor are to control switching of the power transistor. The tap terminal is coupled to provide a signal to the control circuit substantially proportional to a voltage between the first and second main terminals when the voltage is less than a pinch off voltage. The tap terminal is coupled to provide a substantially constant voltage that is less than the voltage between the first and second main terminals to the control circuit when the voltage between the first and second main terminals is greater than the pinch-off voltage.

Abstract: A lower-cost and more precise control methodology of regulating the output voltage of a flyback converter from the primary side is provided, which works accurately in either continuous voltage mode (CCM) and discontinuous mode (DCM), and can be applied to most small, medium and high power applications such cell phone chargers, power management in desktop computers and networking equipment, and, generally, to a wide spectrum of power management applications. Two highly integrated semiconductor chips based on this control methodology are also described that require very few components to build a constant voltage flyback converter.

Abstract: A rectification switch control switch element (Q7) is provided between a gate and a source of a rectification switch element (Q2). The rectification switch control switch element (Q7) is turned ON in response to a signal on a secondary side of a pulse transformer (T2) at a turn OFF timing of a main switch element (Q1) to forcedly turn OFF the rectification switch element (Q2). As a result, the rectification switch element (Q2) can be turned OFF in synchronism with an OFF of the main switch element at a time of a backflow. With use of a free resonance between a capacitance between a gate and a source of the rectification switch element (Q2) and a commutation switch element (Q3) and a choke coil (L2), an excitation state of the choke coil (L2) can be reset. Then, it is possible to stabilize a detection voltage of a tertiary rectification smoothing circuit (22) which uses a tertiary winding (N13) of a transformer (T1), thus stabilizing control of the circuit functions.

Abstract: In one embodiment, a switching controller uses an auxiliary winding voltage of a transformer to form a signal representative of current flow through a secondary winding of the transformer. The controller id configured to limit a current through a secondary winding to a maximum value.

Abstract: We describe a switch mode power supply (SMPS) current regulation system comprising: a current sense signal input sensing a primary current of the SMPS; a voltage sense input to receive a voltage sense signal from a primary or auxiliary winding; a switch drive signal input to receive a drive signal; a timing signal generator coupled to said voltage sense input and to said drive signal input to generate a timing signal T0 indicating a duration of a period for which current is flowing through said primary winding and a timing signal T1 indicating a duration of a period for which current is flowing through said secondary winding; and a regulator to provide an output current regulation signal responsive to an average of the current sense signal multiplied by a ratio of T1 to T0, and wherein T0 and/or T1 are generated responsive to the voltage or current sense signal.

Abstract: A control circuit for adjusting leading edge blanking time is disclosed. The control circuit is applied to a power converting system. The control circuit adjusts a leading edge blanking time according to a feedback signal relative to a load connected to the output terminal of the power converting system. An over-current protection mechanism of the power converting system is disabled within the leading edge blanking time.

Abstract: A control circuit having a programmable waveform for the output power limit comprises an oscillation circuit to generate an oscillation signal. The oscillation signal is used for producing a switching signal to control a switching device in response to a feedback signal of the power converter. A waveform generator generates a waveform signal in accordance with the oscillation signal. The waveform signal controls the control signal and limits the output power of the power converter. A resistor is coupled to the waveform generator to program the waveform of the waveform signal. By properly selecting the resistance of the resistor, which can be used to achieve an identical output power limit of the power converter for the low line and high line voltage input.

Abstract: A semiconductor device includes: a high breakdown voltage semiconductor element including a switching element and a JFET element; and a sense element. The sense element includes a first drift region of a first conductivity type, a first base region of a second conductivity type, a first source region of a first conductivity type, a first gate insulating film, a first drain region of a first conductivity type, a sense electrode electrically connected to the first source region, a first gate electrode, and a first drain electrode electrically connected to the first drain region. The first gate electrode of the sense element and the second gate electrode of the switching element are connected to each other. The first drain electrode of the sense element and the electrode shared by the switching element and the JFET element are connected to each other.

Abstract: The subject invention reveals improvement methods for circuits that use a coupled inductor wherein overshoot and ringing associated with leakage inductance of said coupled inductor is entirely eliminated by addition of non-dissipative active clamp networks that clamp each winding during each operating state of a power supply containing said coupled inductor. A further improvement applicable to zero voltage switching circuits that employ an inductor for driving a zero voltage turn on switching transition of a switch enables elimination of said inductor and preserves said zero voltage switching properties by adding leakage inductance to a coupled inductor without any adverse overshoot and ringing effects associated with said leakage inductance. The subject invention also reveals a coupled inductor with enhanced leakage inductance which can be used with said other improvements.

Abstract: Techniques are disclosed to regulate an output current through a load coupled to a power converter using a current source coupled to the load. For instance, one power converter according to the teachings of the present invention includes an energy transfer element coupled between an input of the power converter and an output of the power converter. A power converter controller is coupled to the energy transfer element to control a transfer of energy from the input of the power converter to the output of the power converter. A load is to be coupled to the output of the power converter. A current source is to be coupled to the load. The current source regulates the current flowing through the load to a threshold current value. The current source is coupled to sense a current through the load. A switch having a first and second end is also included. The first end is to be coupled to the load and the second end is coupled to the current source.

Abstract: The invention relates to a switched-mode power supply system comprising two buffer capacitors connected in series and connected between the two input terminals of a DC input voltage source, two switches connected in series, a primary inductive assembly connected in series with the two switches, and a secondary winding magnetically coupled to the primary inductive assembly in order to deliver a DC output voltage. A current injection module injects current at a mid-point of the two buffer capacitors in order to generate a current imbalance at this mid-point. A balancing circuit for balancing the leakage currents of the capacitors, one end of said balancing circuit being connected to the mid-point of the buffer capacitors, maintains this imbalance at a predetermined value. The invention also relates to a speed variator using such a power supply system.

Abstract: A control circuit for controlling a subsidiary (high-side) switching device in an insulating electric power converter having a half-bridge structure includes a first series circuit of a resistor and a diode, a second series circuit of a resistor and a diode, and a transistor. The control circuit turns the subsidiary switching device ON and OFF using the voltage generated in a transformer winding for a signal voltage. The control circuit also turns the transistor ON and OFF with the voltages generated in the first and second series circuits so as not to make the gate voltage of subsidiary switching device exceed the gate breakdown voltage thereof in all the operation modes.

Abstract: A converter having a plurality of channels includes a transformer having a primary winding and at least one secondary winding. A first switch connected to the primary winding chops a substantially DC voltage in compliance with a first squarewave periodic signal to form an input signal presenting a positive sequence phase and a freewheel phase. A second switch at the input of one of the channels chops an output signal at the secondary winding corresponding to the channel in compliance with a second squarewave periodic signal. The converter also includes a measurement component for measuring a primary current and connected to the primary winding. The converter further includes a storage component for storing a plurality of measured values corresponding to the primary current, the values being measured at distinct times during the positive sequence phase of the input signal, and also includes a processor for processing the measured values.

Abstract: A fly-forward converter topology for a switched-mode power supply (SMPS) that may incorporate the advantages of both a forward converter and a flyback converter into a two-stage half-wave converter is provided. The fly-forward converter may be considered as a half-wave forward converter that has been modified with the addition of another secondary winding and a second rectifier, operating as a forward converter during the on period of the primary-side switch(es) and functioning as a flyback converter during the off period. Magnetizing energy stored in the core of the converter's transformer is not lost or recirculated in the primary, but may be transferred from the primary to the secondary. By transferring the transformer magnetizing energy to the secondary during the off period, the transformer core of the fly-forward converter may be reset without additional core resetting circuitry.

Abstract: An exemplary DC to DC converter includes a first transistor, a second transistor, a transformer, and a pulse generating circuit having a first capacitor, a sampling resistor, a zener diode, and a first diode. A DC voltage input terminal is configured for receiving a first DC voltage and is grounded via the primary winding of the transformer, a collector electrode and an emitter electrode of the first transistor in series. A terminal of the auxiliary winding of the transformer is grounded via the inverted first diode, the non-inverted zener diode, the sampling resistor, and the first capacitor. The other terminal of the auxiliary winding is grounded. A first transistor having a base electrode connected to the DC voltage input terminal. A second transistor includes an emitter electrode a cathode of the zener diode, a collector electrode connected to a base electrode of the first transistor, and a grounded base electrode.

Abstract: A power converter includes: a transformer controlled by a main switch to receive an input power according to a driving signal; a switching circuit outputting a sync signal; and a driving circuit including a dead time controller that includes first and second switches operating according to the sync signal, and an inverse phase generator that includes third and fourth switches and that generates a switching signal. A circuit switch of the switching circuit operates according to the switching signal. Transition of the driving signal from high to low causes the switching signal to transition from low to high with a dead time between a falling edge of the sync signal and a rising edge of the switching signal. Transition of the driving signal from low to high causes the switching signal to transition from high to low with a dead time between a falling edge of the switching signal and a rising edge of the sync signal.

Abstract: An AC/DC power converter has, as its first stage, a capacitor divider and rectifier and, as the second stage, a switch mode power supply. This configuration may be suitable for low power low voltage aerospace applications. The benefits of the circuit may include small reactive component size; near sinusoidal input current, low EMI emissions resulting from low inrush current; intrinsic current limiting that may eliminate the need for short circuit protection; and low overall component count.

Abstract: The present invention is an AC/DC (alternating current to direct current) converter. The converter contains two semi-stages. One is the boost-flyback semi-stage that has excellent self-PFC property when operating in DCM even though the boost output is close to the peak value of the line voltage. Moreover, it allows part input power transferred to load directly through the flyback path so the power conversion efficiency is improved. The other one is the D/DC semi-stage that provides another parallel power flow path and improves the regulation speed.

Abstract: A mixed flyback-forward topology converter includes a transformer having a core, a primary winding, a first secondary winding and a second secondary winding. A switch connects power to the primary winding. A forward stage is connected to the first secondary winding. A flyback stage is connected to the second secondary winding. An output voltage is provided by the flyback stage when the switch is in an off state and by the forward stage when the switch is in an on state.

Abstract: Provided herein is a power factor correction (PFC) power supply, comprising: a bridge rectifier having an input and an output, a filter capacitor connected to the output of the bridge rectifier, a transformer having a primary winding, a fly-back winding and a secondary winding, a forward diode, a fly-back diode, a storage capacitor circuit having a valley-fill circuit and a capacitor connected in parallel, and a switch connected between the primary winding and the output of the bridge rectifier. The PFC power supply features improved efficiency and low switching loss.

Abstract: A switching mode power supply and method for generating a bias voltage is described. The bias voltage is generated by using a current source coupled to a primary coil of a transformer during the start-up of the switching mode power supply. The generation of the bias voltage through the current source is stopped at a second time, a delay time after a first time when the bias voltage becomes essentially equal to a reference voltage that is an operational voltage of a PWM controller. The switching operation of a main switch is started after the first time, when the bias voltage exceeded the operational voltage. In this interval the bias voltage is also generated by the secondary coil of the transformer.

Abstract: A switching power supply, in which a switching element turns on and off electric current flowing on the primary side of an output transformer so as to rectify and output a pulsating flow generated on the secondary side of the output transformer, includes a voltage detecting section that detects an output voltage, a current detecting section that detects electric current flowing through a power transistor as the switching element, a controller that compares a voltage detection signal from the voltage detecting section and a current detection signal from the current detecting section to control the duty of the power transistor during an ON time, and a slope compensation circuit that compensates the rate of change of the voltage detection signal using a slope compensation signal. The slope compensation circuit subtracts the slope compensation signal from the voltage detection signal and outputs the resulting signal to a PWM comparator.

Abstract: A pulse power source comprises a first circuit, a second circuit, a transformer for coupling the first circuit and the second circuit, and a switching controller. The second circuit comprises a third semiconductor switch connected in series with a secondary winding of the transformer. The third semiconductor switch is connected in such a direction that a voltage generated in the second circuit is reverse-biased during a period in which the second semiconductor switch is turned on. A gate amplifier for forming a control signal from the switching controller into a pulse and outputting the pulse as a pulse signal is connected between a gate terminal and a cathode terminal of the third semiconductor switch.

Abstract: A first drive control signal regenerating circuit outputs an ON timing drive signal at turn-ON of a main switch element, and a second drive control signal regenerating circuit generates an OFF timing drive signal at turn-OFF of the main switch element. A rectifying switch controlling switch element connected between the gate and source of a rectifying switch element is driven by an output of the second drive control signal regenerating circuit. An output of the first drive control signal regenerating circuit connects to the gate of a commutating switch controlling switch element, which connects to one end of an auxiliary winding, the other end thereof being connected to the gate of a commutating switch element. Accordingly, the rectifying switch element is directly controlled from the primary side.

Abstract: A switching power supply device has a large load power supply line for a CRT circuit, to and from which a dummy resistor for voltage stabilization is connected and disconnected by a switch. In standby state, a control unit turns off the switch to disconnect the dummy resistor from the power supply line. When receiving a power supply ON command input by a user operating a remote control, the control unit turns on the switch to connect the dummy resistor to the power supply line. At a predetermined time after the dummy resistor connection, the control unit makes a regulator active to start providing voltage to a video/audio signal processing circuit with sufficient current providable thereto. This enables to reduce power consumption of the power supply line with the dummy resistor, and to prevent problems caused by insufficient current in transient state from standby state to power supply ON state.

Abstract: A pulse frequency modulation (PFM) controller for controlling a switching mode power supply. The controller includes an output terminal for providing a control signal to turn on and off a current in the power supply to regulate an output of the power supply. A first input terminal receives a feedback signal related to the output of the power supply, the feedback signal exhibiting a ringing waveform when the current in the power supply is turned off. The controller also includes a control circuit configured to provide the control signal in response to the feedback signal. The control signal is adapted to turn on the current in the power supply when the feedback signal is substantially at a valley of the ringing waveform of the feedback signal. In an embodiment, such a PFM controller can reduce turn-on transition loss in a power supply and provides frequency dithering to reduce electromagnetic interference.

Abstract: The separately-excited inverter circuit for performing the protecting operation upon the rise in the output voltage caused by the contact failure includes a switching circuit 26b which applies the AC to a primary coil of a pressure-rising transformer 26e, a control circuit C1 which starts a switch control of the switching circuit 26b upon an input of a command signal to set an oscillation state ON from a transmission line for the command signal to command to set the oscillation state ON and OFF, an output voltage monitor circuit 51 which allows a comparator 51a to compare an output voltage of the separately-excited inverter circuit with a predetermined voltage, and to output a predetermined reference voltage when the output voltage is higher than the predetermined voltage, and a thyristor circuit 52 which is turned ON to set the transmission line of the command signal into an oscillation OFF state upon the input of the reference voltage to the gate to stop a switch control of the control circuit C1.

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 synchronously switched buck post regulator is revealed for multi-output forward converters. The synchronously switched buck post regulator accomplishes precise independent load regulation for each output and reduced magnetics volume by using a coupled inductor with a common core for all outputs plus a second smaller inductor for each output except the highest voltage output.

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.