Abstract: A power control system includes a current transformer to step down a switch current of a switching power converter. In at least one embodiment, the stepped down current is received by a switching power converter controller. Since the current is received by the controller, the current is not converted into a voltage prior to receipt by the controller in order for the controller to monitor an inductor current of the switching power converter. In at least one embodiment, the controller compares the stepped down switch current with a reference current. In at least one embodiment, the controller includes a voltage converter to convert the switch current into a voltage within the controller. The controller compares the voltage representing the switch current with a reference voltage. The controller can use the current or voltage comparisons to control power factor correction and output voltage regulation of a switching power converter.

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

Abstract: In an integrated transformer assembly, a common coil member has a first portion alternately wound, for each one electromagnetic turn, around the first core member and around the second core member. The first portion of the common primary coil member wound around the first core member is magnetically linked to the first magnetic path thereof so as to constitute a first primary coil. The first portion of the common primary coil member wound around the second core member is magnetically linked to the second magnetic path thereof so as to constitute a second primary coil. The first and second primary coils are connected in series. A secondary coil member has first and second secondary coils. The first and second secondary coils are arranged to be magnetically linked to the first and second primary coils of the common primary coil member, respectively.

Abstract: A method of supplying a power to elements in a power supply apparatus including a primary side and a second side. Particularly, a method of supplying a driving power to an element at the primary side of the power supply apparatus from a primary coil of a transformer. A power factor improvement section improves a power factor of a received alternating current (AC) power. A transformer then receives the AC power having the improved power factor from a primary coil and generates an induced power at a secondary coil. The transformer then provides the AC power to drive a predetermined element located at the primary side of the power supply apparatus from the primary coil.

Abstract: The present invention discloses a standby power saving method for power module applications, comprising the steps of: generating a mode signal according to voltage comparison of a feedback signal and a threshold voltage, wherein the mode signal has a normal mode state and a standby mode state; generating a pulse signal according to the mode signal, wherein the pulse signal has a normal PWM mode responsive to the normal mode state of the mode signal, and a VCC mode responsive to the standby mode state of the mode signal; and generating a gating signal according to the pulse signal for driving a primary side power switch. The present invention also provides a standby power saving apparatus for power module applications.

Abstract: Voltage converters with integrated low power leaker device and associated methods are disclosed herein. In one embodiment, a voltage converter includes a switch configured to convert a first electrical signal into a second electrical signal different than the first electrical signal. The voltage converter also includes a controller operatively coupled to the switch and a leaker device electrically coupled to the controller. The controller is configured to control the on and off gates of the switch, and the leaker device is configured to deliver power to the controller. The leaker device and the switch are formed on a first semiconductor substrate, and the controller is formed on second semiconductor substrate separate from the first semiconductor substrate.

Abstract: In one embodiment, a method of operating a switched-mode power supply having a switch coupled to a drive signal is disclosed. The method includes shutting off the switch with the drive signal at a first instance of time, and comparing a magnitude of a voltage of a power supply node to a threshold after shutting off the switch. If the magnitude of the voltage of the power supply node exceeds the threshold, the switch is inhibited from turning on for a first time interval.

Abstract: An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.

Abstract: A circuit includes a pulse transformer having primary and secondary windings. An oscillating waveform is applied to the primary winding to induce an oscillating waveform at the secondary winding. A transistor in series with a first resistor is coupled between the secondary winding and the ground. An R-C network formed by a second and a third resistor and a capacitor is coupled to a base junction of the transistor. The R-C network causes a slow, tapered linear pinch off of the transistor's conductance to enable the circuit to output a triangular waveform, which is characterized by a relatively short linear rise time followed by a substantially long linear fall time. The R-C network is coupled to the secondary winding via a first and a second diode, respectively.

Abstract: An SAR analog-to-digital converter performs bit decisions in each of a plurality of clock cycles. A sense circuit monitors signals input to a latch within a comparator of the ADC and, when the signals are sufficient to establish a bit decision, the sense circuit terminates a currently active clock cycle causes a bit decision to occur in advance of a normal expiration of the clock cycle. If the signals are insufficient to establish a bit decision prior to a default expiration time of the clock cycle, the clock cycle concludes at the default expiration time.

Abstract: To reduce power loss during standby. In a switching power supply device using a first power supply circuit (11) having a small output and a second power supply circuit (12) having a large output, the first power supply circuit (11) is continuously kept in an operating state and the second power supply circuit (12) is started by using an electric power generated in the first power supply circuit (11).

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 supply apparatus includes an AC-DC rectifier, a transformer, a feedback inductor, a resonant unit, and a primary and auxiliary switch. The AC-DC rectifier rectifies an input voltage. The transformer includes a primary coil having a first primary coil and an isolated second primary coil, and transforms a first voltage of the primary coil into a second voltage of the secondary coil. The feedback inductor is connected to a tap between the first primary coil and second primary coil and an output of the AC-DC rectifier. The resonance unit is connected in parallel with the secondary coil and is configured to output an output voltage by rectifying the second voltage provided from the secondary coil. The primary switch and secondary switch are connected in parallel between the transformer and AC-DC rectifier.

Abstract: A controller for a switching mode power supply includes two semiconductor chips. The first semiconductor chip has a high-voltage startup transistor coupled to a high-voltage supply input terminal and configured to provide a charging current in a startup phase or protection mode of a switching mode power supply (SMPS) and to provide substantially no current in a normal operation phase of the SMPS. The second semiconductor chip has a control circuit for controlling the switching mode power supply. The second semiconductor chip also has first and second on-chip high-voltage resistors coupled to the high-voltage supply input terminal and the high-voltage startup transistor in the first semiconductor chip. The first and the second on-chip high-voltage resistors are configured to provide a voltage and a current related to a voltage at the high-voltage supply input terminal.

Abstract: An example power converter includes a power switch, a controller, and a current offset circuit. The controller is coupled to switch the power switch between an ON state and an OFF state to regulate an output of the power converter. The controller is adapted to terminate the ON state of the power switch in response to a switch current flowing through the power switch reaching a switch current threshold. The current offset circuit is coupled to generate an offset current in response to an input voltage of the power converter and an input current of the power converter is adjusted in response to the offset current.

Abstract: A history-independent and noise-immune modulated transformer-coupled gate control signaling method and apparatus provides robust design characteristics in switching power circuits having a transformer-coupled gate drive. A modulated control signal at a rate substantially higher than the switching circuit gate control rate is provided from the controller circuit to a demodulator via transformer coupling. Codes specified by relative timing of transitions in multiple periods of the modulated control are assigned to gate-on and gate-off timing events that control the switching transistor gate(s) and unassigned patterns are decoded as gate-off events, reducing the possibility that a switching transistor will be erroneously activated due to noise. The modulated signal is constructed so that signal history is not required for decoding, eliminating any requirement of a reference clock. Blanking may be employed to conserve power between codes and to avoid mis-triggering due to noise events during power switching.

Abstract: An exemplary embodiment of a flyback power converter includes a transformer for power transfer, a high-side transistor, a low-side transistor, two diodes, a control circuit, and a high-side drive circuit. The high-side transistor and the low-side transistor are coupled to switch the transformer. The two diodes are coupled to said transformer to circulate energy of leakage inductance of the transformer to an input power rail of the power converter. The control circuit generates a switching signal coupled to control the high-side transistor and the low-side transistor. The high-side drive circuit is coupled to receive the switching signal for driving the high-side transistor. The transformer has an auxiliary winding generating a floating power to provide power supply for said high-side drive circuit.

Abstract: An embodiment of the invention provides a converter power-supply apparatus that is efficiently operable for a wide-range load. A power-supply control device controls a boost converter. The boost converter includes a basic switching circuit, an expansion switching circuit that is connected in parallel with the basic switching circuit. A control circuit supplies a control signal to the basic and the expansion switching circuit through a first and a second signal line, respectively. A detecting unit detects a voltage and/or a current in a predetermined point of the boost converter. A comparison circuit compares a detected value with a reference value and supplies a first signal when a load is relatively heavy, a second signal when the load is relatively light. A control signal switch connects the second signal line when receiving the first signal, and disconnects the second signal line when receiving the second signal.

Abstract: Power converter with a controllable first switch and a diode and a controllable second switch and a second diode, a transformer with a primary winding and a secondary winding, of which the secondary winding forms at least part of a control circuit for the first switch. As a result of an alternating voltage across the primary winding, a synchronously alternating voltage is induced in the secondary winding, which can be used to control the first switch essentially synchronously with the second switch.

Abstract: Lower surface terminals are disposed at the lower surface of a magnetic substrate. An upper surface electrode is disposed at the upper surface of the magnetic substrate. A control circuit, an input capacitor, and an output capacitor are mounted on the upper surface electrode. The control circuit contains a switching element. A smoothing choke is disposed inside the magnetic substrate. The connection wiring of connecting the upper surface electrode and at least one of the input terminal, the output terminal, and the ground terminal is constructed using an inner conductor passing through the inside of the magnetic substrate, and the connection wiring forms an inductor.

Abstract: A capacitor charging circuit is provided with a primary side output voltage sensing circuit including an RC network having an RC time constant with a predetermined relationship to the RC time constant of the output capacitor. Once the capacitor voltage reaches a fully charged level, the charging mode is terminated. The output voltage is continuously detected by measuring the voltage across the primary side RC network that decays at a predetermined rate with respect to the output capacitor and the charging mode is commenced once the RC voltage falls to a predetermined level. According to a further aspect of the invention, a switch control circuit in a flyback converter controls the switch off time in response to detection of a change in the slope polarity of the voltage at a terminal of the switch.

Abstract: A power converter is provided that has an alternating-current (AC) to direct-current (DC) switched-mode power converter circuit that converts alternating-current power into direct-current power for powering an attached electronic device. Power can be conserved by automatically placing the power converter circuit in a low-power standby mode of operation whenever the electronic device is detached from the power converter. A monitoring circuit can be powered by a capacitor or other energy storage element while the power converter is operating in the standby mode. If the monitoring circuit detects an output voltage change that is indicative of attachment of the electronic device or if the storage element needs to be replenished, the monitoring circuit can place the power converter circuit in an active mode of operation.

Abstract: An exemplary DC to DC converter (200) includes a first DC input (210) connected to a first DC power supply; a second DC input (220) connected to a second DC power supply; a transformer (230) including a primary winding (231), a sub-primary winding (232), and a secondary winding (233) for outputting a AC voltage; a pulse reverse circuit (260) including an input for receiving a square pulse and an output for providing the reverse square pulse; a first switch transistor (240) including a source connected to ground, a drain connected to the first DC input via the primary winding, and a gate connected to the output of the pulse reverse circuit; a second switch transistor (250) including a source connected to ground, a drain connected to ground via the sub-primary winding and a capacitor in series, and a gate connected to the output of the pulse reverse circuit.

Abstract: A switching power supply apparatus includes a transformer or an inductor, a switching element connected to the transformer or the inductor and configured to perform switching of an input power supply, and a switching control circuit including a digital control circuit configured to sample voltage values and/or current values and control on and off of the switching element in accordance with the voltage values and/or current values. The number of points of sampling is set to n or more points, where n is an integer greater than 3, in an ON period of the switching element except at around a turn-on point or a turn-off point of the switching element. The presence or absence of magnetic saturation of the transformer or the inductor is detected on the basis of whether or not a slope of change in current value over time is larger than a predetermined value, and circuit operation is protected from the effect of magnetic saturation.

Abstract: The power supply apparatus includes a first control part that controls a switching operation of a first converter, a second control part that controls a switching operation of a second converter, a zero crossing circuit that outputs a zero crossing signal of a voltage to be input; and a voltage supply part that supplies a DC voltage obtained by rectifying an output of an auxiliary coil of a transformer of the first converter to the first control part, the second control part, and the zero crossing circuit. When the first converter stops, the supply of the DC voltage to the second control part and the zero crossing circuit is stopped to reduce a power consumption.

Abstract: A switching power supply equipment has a function to protect a power supply from abnormalities such as an output short-circuit. An output signal from an error amplification circuit to amplify a difference voltage between an output voltage and a predetermined voltage is input into a feedback terminal of an integrated circuit power supply control circuit, and a power transistor is controlled by a pulse-width control circuit base on the output signal. n addition, a comparator having a reference voltage and a series circuit of a capacitor and a resistor making operation of an overload protection circuit delay are connected to a connecting point of the error amplification circuit and the pulse-width control circuit. The overload protection circuit starts operation by an output of the comparator.

Abstract: The present invention discloses a power supply control circuit, the power supply providing an output voltage to an output terminal from an input terminal through a transformer having a primary winding and a secondary winding, the power supply control circuit comprising: a power switch electrically connected with the primary winding; a switch control circuit controlling the power switch; and a sensing circuit supplying an output signal to the switch control circuit according to voltage signals obtained from two sides of the primary winding, wherein the sensing circuit includes a setting circuit for deciding the output voltage according to a reference signal. The present invention also relates to a voltage sensing method in the power supply control circuit.

Abstract: A first AC/DC converter circuit is coupled via two transformers to a second AC/DC converter circuit, the first AC/DC converter circuit having a symmetrical configuration of two switching elements performing complementary opened/closed switching, to alternately connect positive and negative terminals of a DC source to a junction between transformer primary windings. Each primary winding alternates between a condition of transferring electrical power to a secondary winding and a condition of serving as a choke coil which temporarily stores electromagnetic energy when a current flows through that primary winding and a primary winding of the other transformer.

Abstract: A power system having a power converter with an adaptive controller. In one embodiment, a power converter coupled to a load includes a power switch configured to conduct for a duty cycle to provide an output characteristic at an output thereof. The power converter also includes a power converter controller configured to receive a signal from the load indicating a system operational state of the load and enable a power converter topological state as a function of the signal.

Abstract: A control arrangement for a voltage converter includes a first input electrically connected to a device configured to sense a first current in a primary side of a transformer and a first output electrically connected to a control terminal of a transistor. The transistor is electrically connected with the primary side of the transformer and the first output is configured to supply a control signal to the control terminal. The control arrangement also includes a computing unit configured to adjust the control signal so that the transistor has a low resistance value during a switched-on phase and a high resistance value during a switched-off phase.

Abstract: The first sampling measurement value compares whether to exceed a prescribed threshold and judges the control part at the sampling time. The control part compares whether the first sampling measurement value exceeds a prescribed threshold. When the actual measurement value doesn't exceed a prescribed threshold, the control part predict the first sampling value at the next sampling time. [1] When the first sampling the predicting value doesn't exceed the threshold value, the status of the switch is maintained, [2] When the first sampling the predicting value exceeds the threshold value, the time when the movement of the switch should be changed is calculated and the status of the switch is changed at time concerned.

Abstract: A high-power modulation system includes drive circuitry that receives input signals from the signal source via a series of transformers. The drive circuitry amplifies the input signals and provides the resulting amplified signals to the high-power switch. The switch includes a series of stacked switching elements, each with a control terminal, first and second current-handling terminals, and feedback path extending between the first current-handling terminal and the control terminal. The feedback paths work in concert to turn the switches on and off together to prevent excessive voltage from developing across one or a subset of the switching elements. The feedback path includes a resistor that dampens the bandwidth of the feedback path to reduce turn-off and turn-on ringing and oscillation. The damping resistor may be coupled in series with a diode that holds charge against the control terminal of the switching element.

Abstract: A power conversion circuit capable of varying an output voltage within a range from a negative voltage lower than a ground voltage to a positive voltage higher than a supply voltage, and a driving method and a drive unit are provided. A power conversion circuit includes a transformer with a 1:1 ratio between the primary winding and secondary winding, a voltage outputting capacitor, and four switches. The power conversion circuit can be operated as a DC-DC converter of a step-up type, a step-up-and-down type, a step-down type, an inverted-output step-up-and-down type, or an inverted-output step-up type by selecting two switches used for control from among the four switches and alternately turning the two switches on. By switching the operating modes of the power conversion circuit, the output voltage can be varied within a range from a negative voltage to a positive voltage higher than a supply voltage.

Abstract: A high-voltage pulse generating circuit includes a direct current power source, a transformer, a switching device and a switching control circuit. The transformer includes a primary winding and a secondary winding. The switching device is connected between the direct current power source and the primary winding. The switching control circuit controls the switching device to be in the non-conductive state after the switching device is set in the conductive state during first conductive time and further controls the switching device to be in the conductive state during second conductive time after one of the voltages of the primary winding and the secondary winding excess the predetermined value and then to be in the non-conductive state.

Abstract: In an insulation type AC-dc converter in which input current from a commercial power supply is converted to obtain insulated direct current, the overall efficiency is raised and the structure is simplified. A multi-resonance type half-bridge DC-DC converter having an insulation transformer T is used as a first converter, and a boosting chopper circuit for power factor improvement is used as a second converter. Hence through multi-resonance operation, increases in losses can be suppressed even when the switching frequency is raised, and because a half-bridge circuit is used, switching elements and similar with lower voltage ratings can be employed, whereby overall efficiency can be increased.

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

Abstract: The invention relates to a half-bridge power converter controller that employs current mode control. The power converter controller includes pulse modulation circuitry, error circuitry, and stabilization circuitry. The stabilization circuitry stabilizes the voltage at the mid-point of a half-bridge power converter input capacitor circuit. The input capacitor circuit mid-point voltage is stabilized by selectively adjusting the on-times of the high-side switch and low-side switch of a half-bridge power converter. This adjustment tailors the current that is provided to the input capacitor circuit and thus maintains the mid-point voltage near a desired value.

Abstract: A digital signal processing circuit which performs average current control is disposed on a secondary side of a transformer of an isolated DC-DC converter, and a switching control signal output from the digital signal processing circuit is transmitted to a switching element included in a power factor correction converter through an isolated drive circuit. The digital signal processing circuit obtains an average value of currents supplied to an inductor in accordance with a voltage output from a bias winding of the inductor or an output from a secondary side of a current transformer which detects a drain current of the switching element. Furthermore, the average value of the currents corresponds to a waveform (full-wave rectification sine wave) of an input voltage Vi.

Abstract: An inductance element (1) includes a doughnut-shaped magnetic core (2) having a wound body or a stacked body of a magnetic ribbon, a bottomed container (3) in which the doughnut-shaped magnetic core (2) is housed, and a conductive lead portion (5) inserted into a hollow section of the doughnut-shaped magnetic core (2) housed in the bottomed container (3). An open section of the bottomed container (3) is covered with an adhesive portion (4) which integrally fixes the doughnut-shaped magnetic core (2), the bottomed container (3) and the conductive lead portion (5). The adhesive portion (4) is entered into a gap between the doughnut-shaped magnetic core (2) and the bottomed container (3) and a gap between the bottomed container (3) and the conductive lead portion (5) in a range of 5 to 50% in average to a thickness of the doughnut-shaped magnetic core (2).

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: A small and efficient DC-DC converter is provided. In this DC-DC converter, passive elements such as an inductor and a capacitor can be reduced in size by reducing switching loss by a soft switching technology and increasing the drive frequency of a switching element. The DC-DC converter has a main switching element, a main diode and an auxiliary circuit that discharges the electric charges of the capacitance between the ends of the main switching element. The DC-DC converter includes an auxiliary inductor magnetically coupled with the main inductor, an auxiliary switching element that stores energy in the auxiliary inductor, and an auxiliary diode that discharges energy stored in the auxiliary inductor to the direct-current power source or the output side. The auxiliary inductor is coupled with the main inductor in the direction in which backward voltage is applied to the auxiliary diode when the main inductor discharges energy.

Abstract: Disclosed is a small-size, high-efficiency, isolated, bidirectional DC-DC converter. The bidirectional DC-DC converter includes a transformer in which windings are magnetically coupled, switching circuits, a diode which is connected in parallel with a switch, smoothing capacitors, and a control section. First and second DC power supplies, which are connected in parallel with the smoothing capacitors, respectively, provide bidirectional electrical power transfer. When electrical power is to be transferred from the first DC power supply to the second DC power supply, the switch is maintained in the ON state. When, on the other hand, electrical power is to be transferred from the second DC power supply to the first DC power supply, the switch is maintained in the OFF state to prevent a reverse electrical power flow from the first DC power supply.

Abstract: Circuitry includes an acquiring circuit to acquire period and phase information of an oscillation. The acquiring circuit includes a first input electrically coupled to a first connection and a second input electrically coupled to a second connection. The first connection and the second connection are for electrically coupling to an oscillating circuit. A control circuit includes a first input electrically coupled to an output of the acquiring circuit. The control circuit includes a second input electrically coupled to a third connection for supply of a voltage that is based on the rectified voltage. A switch includes a controlled segment for electrically coupling a fourth connection to a reference potential connection, and a control connection that is electrically coupled to an output of the control circuit to excite an oscillation in the oscillating circuit via a DC voltage.

Abstract: A modulated transformer-coupled gate control signaling method and apparatus provides reduction of circuit complexity and robust design characteristics in switching power circuits having a transformer-coupled gate drive. A modulated control signal at a rate substantially higher than the switching circuit gate control rate is provided from the controller circuit to a demodulator via transformer coupling. Power for the demodulator can be obtained by rectifying the modulated control signal at the demodulator, or from another transformer winding. The modulation scheme is chosen to have a DC average value of zero, eliminating any magnetization current management requirements. The modulated control signal may carry redundant control information and/or may encode additional information to provide a more sophisticated gate drive control, such as oversampled gate control information.

Abstract: A capacitor charging circuit is provided with a primary side output voltage sensing circuit for generating a control signal indicative of whether the output voltage has reached a desired level. The control signal is unaffected by voltage spikes occurring when the main switch is turned off. In one embodiment, the circuit filters the primary side voltage for comparison to a reference voltage in order to provide the control signal. In another embodiment, an AND gate provides the control signal indicating that the output voltage has reached the desired level only in response to the primary side voltage being greater than a reference voltage and the secondary current being discontinuous. In a further embodiment, an AND gate provides the control signal indicating that the output voltage has reached the desired levels only in response to a predetermined delay occurring after the primary side voltage becomes greater than a reference voltage and the secondary current being discontinuous.

Abstract: A PWM controller compensates a maximum output power of a power converter, and includes a PWM unit and a compensation circuit. The PWM unit generates a PWM signal for controlling a power switch to switch a power transformer, which has a primary winding connected to the power switch and is supplied with an input voltage of the power converter. A pulse width of the PWM signal is correlated to an amplitude of the input voltage. The compensation circuit generates a current boost signal in response to the PWM signal by pushing up a peak value of a current-sense signal generated by a current-sense device in response to a primary-side switching current of the power transformer. A peak value of the current boost signal is adjusted by the pulse width of the PWM signal for compensating a difference of the maximum output power caused by the amplitude of the input voltage.

Abstract: The ON duration of an N channel MOS transistor is set based on a target voltage at a node between a resistor and a light receiving element of a photocoupler. A comparator compares the target voltage with a reference voltage at a node between a variable resistor and a resistor. A normal mode and a low frequency operation mode are switched from one to the other based on an output signal from the comparator. The resistance of the variable resistor becomes low when an input voltage from a power source is high. Even when the input voltage is high, therefore, the ON duration of the N channel MOS transistor at the transition between the normal mode and the low frequency operation mode becomes short. This reduces the switching energy in low frequency operation mode, thereby suppressing noise.

Abstract: A switching mode power supply and a method of operating the power supply in a power save mode. The switching mode power supply includes a first PWM controller and a second PWM controller that are driven by different driving voltages and control first and the second voltages to be output, respectively, a first transformer that is controlled by the first PWM controller to output the first voltage and having a primary coil, a secondary coil to induce the first voltage, and an auxiliary winding, and a rectifier that rectifies and smoothes a current flowing through the auxiliary winding of the first transformer, generates a power save mode voltage based on the respective driving voltages of the first and the second PWM controllers, and supplies the power save mode voltage to the first and the second PWM controllers. Accordingly, the power save mode is operated using a voltage difference without requiring an extra controller.

Abstract: A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

Abstract: A switching mode power supply and a method of operating the power supply in a power save mode. The switching mode power supply includes a first PWM controller and a second PWM controller that are driven by different driving voltages and control first and the second voltages to be output, respectively, a first transformer that is controlled by the first PWM controller to output the first voltage and having a primary coil, a secondary coil to induce the first voltage, and an auxiliary winding, and a rectifier that rectifies and smoothes a current flowing through the auxiliary winding of the first transformer, generates a power save mode voltage based on the respective driving voltages of the first and the second PWM controllers, and supplies the power save mode voltage to the first and the second PWM controllers. Accordingly, the power save mode is operated using a voltage difference without requiring an extra controller.