Abstract: A power conversion apparatus supplies power to a load, and the power conversion apparatus includes a power switch, a transformer, and a control module. The control module alternately turns on and turns off a power switch of the power conversion apparatus to convert an input voltage into an output voltage through the transformer. When the power switch is turned off, a primary side of the transformer generates a resonance voltage. The control module sets a predetermined counting threshold according to the output voltage, and sets a blanking time interval according to a feedback signal related to the load. After the blanking time interval ends, the control module counts a number of an oscillation turning point generated by the resonance voltage due to the oscillation of the resonance voltage. When the number reaches the predetermined counting threshold, the control module turns on the power switch.

Abstract: In an embodiment, an USB interface includes a transformer, a primary winding of the transformer and a first switch connected in series between a first node and a second node, a secondary winding of the transformer and a component connected in series between a third node and a fourth node, the fourth node configured to be set a first reference potential, a second switch connected between the third node and a first terminal, the first terminal configured to provide an output voltage of the USB interface; wherein the component is configured to avoid a current circulation in the secondary winding when the first switch is closed and a control circuit configured to compare a first voltage of an interconnection node between the secondary winding and the component to a first threshold and compare the first voltage to a second threshold when the first voltage is, in absolute values, above the first threshold.

Abstract: A startup control method for a DC/DC converter is used for starting the DC/DC converter with energy transferred from a low-voltage side to a high-voltage side, and includes: determining a duty cycle or a frequency of a driving signal based on at least a voltage spike reference value and a voltage spike measurement value of a power switch at the low-voltage side; and outputting the driving signal to the power switch, thereby controlling the on and off of the power switch. The startup control method for a DC/DC converter of the disclosure can improve a reverse charging power of the converter to the maximum extent and reduce the time needed for charging a bus capacitor during a reverse startup process while ensuring voltage stress on the power switch not to exceed a limit.

Abstract: A short circuit protection circuit may comprise a first configuration channel line extending from a first connector, a first resistor connected to the first configuration channel line; a voltage divider connected to a junction point on the first configuration channel line, the voltage divider comprising a second resistor and a thermistor, and a field effect transistor (FET) comprising a source, gate, and drain. The thermistor may be connected to a ground line. The drain of the FET may be connected to the first resistor, the source of the FET may be connected to the ground line, and the gate of the FET may be connected to a second junction point between the second resistor and thermistor of the voltage divider.

Abstract: An integrated circuit for a power supply circuit that includes a transformer and a transistor controlling an inductor current flowing through a primary winding of the transformer. The integrated circuit includes a terminal receiving a voltage corresponding to the voltage of a secondary winding of the transformer when the transistor is in an off-state, a first detection circuit detecting that the inductor current is smaller than a first current value, and a determination circuit determining whether an AC voltage applied to the primary winding of the transformer is a first or second AC voltage, both based on the received voltage in the off-state of the transistor. The integrated circuit is configured to drive the transistor in response to a detection result of the first detection circuit, a determination result of the determination circuit, and an output voltage of the power supply circuit generated from the AC voltage.

Abstract: A converter for driving a load has a main switch for controlling, at a switching frequency, the path of current flow through a power inductor and power commutation thereof so as to provide an output. A hysteretic control circuit generates a burst signal for turning on and off the power commutation to implement a burst mode operation with a burst frequency lower than the switching frequency. An adjusting circuit adjusts the upper threshold and/or the lower threshold of the hysteretic control in dependence on the detected burst signal. This burst mode hysteresis controlled converter in this way has the hysteresis adapted in dependence on the load being driven so that load regulation problems are reduced.

Abstract: A signal transmission circuit is configured for transmitting control information from a secondary side of a power converter to a primary side of the power converter. The signal transmission circuit includes a transmitter circuit, a signal transformer and a detection circuit. The transmitter circuit is configured to generate a ramp signal at least according to a first control signal outputted from the secondary side. The first control signal indicates the control information provided for a switch in the primary side. The signal transformer, coupled to the transmitter circuit, is configured to convert the ramp signal to generate an output signal. The output signal includes a positive-going component and a negative-going component to indicate the control information. The detection circuit, coupled to the signal transformer, is configured to detect the positive-going component and the negative-going component to provide the control information for the switch.

Abstract: An apparatus comprises a controller operative to: i) monitor a resonant voltage associated with a primary winding magnetically coupled to a secondary winding; ii) control a flow of current through the primary winding to produce an output voltage at the secondary winding; and iii) control magnetization of the primary winding with respect to a detected a zero crossing event associated with the monitored resonant voltage. The controller further controls a duration of activating a switch coupled to an auxiliary winding (which is magnetically coupled to the primary winding) based on a magnitude of the monitored resonant voltage and/or a magnitude of an input voltage supplied to the primary winding. The controller operates in different modes of magnetizing the primary winding such as at peaks or valleys of the monitored resonant voltage depending on a magnitude of the input voltage.

Abstract: The power supply apparatus includes a transformer, a switching element, a full-wave rectification circuit, a smoothing circuit having one end connected to a first primary winding of the transformer, and another end connected to a second primary winding of the transformer through the switching element, and a circuit connected to an output end of the full-wave rectification circuit and including an inductor and a rectifying element connected in series with each other, wherein the number of turns of the first primary winding is greater than the number of turns of the second primary winding.

Abstract: A semiconductor switching circuit associated with a power semiconductor circuit is described. The semiconductor switching circuit includes a snubber circuit comprising a snubber switch element that comprises a first terminal configured to couple to a supply node associated with the power semiconductor circuit and a second terminal configured to couple to a switch node associated with the power semiconductor circuit. In some aspects, the snubber switch element is configured to bypass a ringing voltage at the switch node associated with the power semiconductor circuit to the supply node associated with the power semiconductor circuit. In some aspects, the ringing voltage at the switch node comprises a voltage that is greater than a supply voltage associated with the supply node.

Abstract: Disclosed is a dynamic regulation power controller having a work voltage input pin, a feedback voltage input pin, a driving voltage output pin, a current sensing input pin, and a regulation power input pin, and being in collocation with a switching unit, an input power processing unit, a transformer, a current sensing resistor, a power regulation unit, an output rectification unit, and an output capacitor for converting an input AC voltage into an output voltage for supplying a load. In particular, the driving voltage and the driving current are dynamically adjusted according to the feedback voltage and the current sensing signal, thereby greatly increasing efficiency of power conversion and Electromagnetic Interference (EMI).

Abstract: A system includes an input voltage supply and a switching converter coupled to the input voltage supply. The switching converter includes a transformer having a primary coil and a secondary coil. The switching converter also includes a Y-rated capacitor with a top plate and a bottom plate, wherein the top plate is coupled to a first end of the secondary coil. The switching converter also includes a push-pull current source coupled to the bottom plate of the Y-rated capacitor. The switching converter also includes a controller coupled to the push-pull current source.

Abstract: A resonant or semi-resonant DC/DC converter makes use of one or more synchronous rectification (SR) switches for rectifying an output current that is provided to a load of the converter. The SR switches are ideally turned off when zero current is flowing through them. To achieve such zero-current switching, the current through each of the SR switches is monitored and compared against a turn-off threshold. The turn-off threshold for a particular SR switch is determined from the slope of a waveform of the current together with a transition delay for turning off the SR switch. This transition delay typically includes a delay through a driver circuit for the SR switch together with a latency through the SR switch itself. Once it is detected that the current for an SR switch has dropped to or below the turn-off threshold, a signal is provided to the SR switch turning it off.

Abstract: The disclosure is directed to techniques to determine the output voltage on the secondary side of a power converter. These techniques maintain isolation between the primary and secondary by measuring a voltage on the primary side with a single sample event synchronized to a power cycle of the power converter. A measuring circuit may determine a drain voltage of a primary side switch that controls current to the primary side coil. The measuring circuit may sample the drain voltage at a predetermined delay time from a trigger pulse based on a control signal to the primary side switch. The output voltage may be calculated based on the sampled drain voltage and other characteristics of the flyback converter circuit, such as transformer turns ratio, primary side input voltage and other characteristics. The output voltage calculation does not require auxiliary windings or isolation components, such as an opto-coupler.

Abstract: A flyback power converter circuit includes a transformer, a power switch, a primary side controller circuit, and a secondary side controller circuit. The transformer converts an input voltage to a first, a second and a third output voltages. The primary side controller circuit and the secondary side control are powered by the second voltage and a third voltage, respectively. In a burst mode, when the second output voltage is lower than a first threshold, a power regulation mode is triggered to control the power switch, such that the second output voltage is between the first threshold and a second threshold. After a predetermined delay time period, the power regulation mode stops and the flyback power converter circuit enters a reboot procedure, wherein the power switch is OFF such that the third voltage is lower than a secondary side reboot threshold, whereby the secondary side controller circuit is reboot.

Abstract: A dual-output flyback voltage conversion circuit and a display device are provided. The dual-output flyback voltage conversion circuit includes an input module, a voltage transformation module, an output module, and a feedback module. The input module is used for rectifying and filtering an input voltage. The voltage transformation module is used for performing a voltage conversion process on the input voltage which is obtained after rectifying and filtering. The output module is used for outputting a first output voltage and a second output voltage according to conversion voltages. The feedback module is used for controlling the voltage transformation module to output the input voltage which is obtained after rectifying and filtering according to the first output voltage and the second output voltage.

Abstract: An exemplary embodiment of an alternating valley switching controller is provided. The alternating valley switching controller includes a valley detection circuit and an alternating circuit. The valley detection circuit is coupled to an auxiliary winding of a transformer to generate a valley-detection signal. The alternating circuit alternates a plurality of switching periods of a switching signal according to a blanking-window signal and the valley-detection signal. The blanking-window signal switches between a first voltage level and a second voltage level in the plurality of switching periods. The plurality of switching periods includes at least two first periods and at least two second periods which occur alternately in response to the first voltage level and the second voltage of the blanking-window signal.

Abstract: Systems and methods are provided for regulating a power conversion system. An example system controller includes a first controller terminal and a second controller terminal. The first controller terminal is configured to receive a first signal associated with an input signal for a primary winding of a power conversation system. The second controller terminal is configured to output a drive signal to a switch to affect a first current flowing through the primary winding of the power conversion system, the drive signal being associated with an on-time period, the switch being closed during the on-time period. The system controller is configured to adjust a duration of the on-time period based on at least information associated with the first signal.

Abstract: A control circuit for a switch mode power supply (SMPS) includes a power switch for coupling to a primary winding of the power supply and a startup resistor coupled to an external input voltage and to a control terminal of the power switch. The control circuit also includes a controller. During startup, the controller is configured to cause the power switch to amplify a startup current from an external input voltage through the startup resistor and provide a startup power to the controller. During normal operation, the controller is configured to provide a power switch control signal to turn on and off the power switch for controlling a current flow in the primary winding and regulating an output of the power supply. The controller is configured to provide a current signal for driving an NPN power switch and to provide a voltage signal for driving an NMOS power switch.

Abstract: A power supply includes a transistor that is connected to a primary winding of a transformer. A controller controls a switching operation of the transistor by quasi-resonant switching. The controller receives a feedback voltage and adjusts the feedback voltage to adjust a blanking frequency, which is an inverse of a blanking time during which the transistor is prevented from being turned on. The controller turns on the transistor after expiration of the blanking time based on a level of a resonant ring.

Abstract: The present disclosure relates to a controller and a controlling method of a switching power supply. The controller of the switching power supply is used for turning on and off a power transistor so that inductor current flows through an inductor which is connected in series with the power transistor. The controller includes a frequency-jittering signal generating circuit, a superimpose circuit and a first comparator. The frequency-jittering signal generating circuit generates a frequency-jittering signal variable over time. The superimpose circuit superimposes the frequency-jittering signal on a sampling signal of the inductor current to generate a superimposed signal. The first comparator compares the superimposed signal with a control voltage to generate an OFF signal for turning off the power transistor. The controller of the switching power supply reduces conducted electromagnetic interference by a frequency-jittering control on the sampling signal of the inductor current.

Abstract: Techniques are provided for controlling power switches that couple an input power source to a transformer within a voltage converter, in order to control the power transfer through the transformer and to a load of the voltage converter. Different techniques are provided for different operational modes. In an initial steady-state interval, the switches are switched using a fixed first switching period and variable duty cycle. Upon detecting a load transient, e.g., a sudden increase in the load power requirements, a ramp-up interval is entered during which the switches are switched using a second switching period and a second duty cycle, in order to increase the output current of the converter at a maximum rate. Upon detecting that a current within the voltage converter has reached a maximum allowed level, a current-limited interval is entered during which the switches are switched using a third switching period and a third duty cycle.

Abstract: Systems and methods for mitigation of resistor nonlinearity errors in a power converter are provided. In at least one embodiment, the power converter comprises at least one power switch coupled to an input voltage, a pulse width modulation (PWM) circuit for generating control pulses for the at least one power switch, at least one output inductor coupled to a respective one of the at least one power switches, a current sensor coupled in parallel with the at least one output inductor, and at least one circuit element. The current sensor comprises at least one capacitor, at least one resistor for each of the at least one output inductors, and is coupled to the PWM circuit at a current bleed node. The at least one circuit element is coupled to the current bleed node and bleeds a bleed current from the current bleed node when a power switch is turned on.

Abstract: A control circuit for a switch mode power supply (SMPS) includes a power switch for coupling to a primary winding of the power supply and a startup resistor coupled to an external input voltage and to a control terminal of the power switch. The control circuit also includes a controller. During startup, the controller is configured to cause the power switch to amplify a startup current from an external input voltage through the startup resistor and provide a startup power to the controller. During normal operation, the controller is configured to provide a power switch control signal to turn on and off the power switch for controlling a current flow in the primary winding and regulating an output of the power supply. The controller is configured to provide a current signal for driving an NPN power switch and to provide a voltage signal for driving an NMOS power switch.

Abstract: A jitter control circuit, which reduces conducted EMI noise by giving jitter (frequency diffusion) to the operating frequency for driving a switching element, determines an operating frequency fc (e.g., 40 kHz) at which reduction effects change from a feedback voltage that represents magnitude of a load. The jitter control circuit causes a, for example, 8-bit counter that generates a modulation frequency to operate with, for example, 8 bits when 40 kHz?fc and 7 bits when fc<40 kHz. In this way, even when the range of the EMI noise measurement frequency is extended to the lower frequency side, for example, to 25 kHz, the maximum reduction effect is maintained in the entire frequency range. Thus, the maximum EMI noise reduction effect is obtained.

Abstract: A control circuit of a power supply is provided. The control circuit includes a circuit and a PWM circuit. The circuit generates a limit signal in response to an output voltage of the power supply for limiting a switching current of a transformer of the power supply. The PWM circuit generates a switching signal in response to a feedback signal and the limit signal for switching the transformer and regulating the output voltage of the power supply. A level of the feedback signal is related to a level of the output voltage of the power supply. The output voltage of the power supply is programmable.

Abstract: A switching power-supply device, in which an input power is applied to a primary winding of a transformer, a pulse voltage is induced in a secondary winding of the transformer by turning on and off a switching element connected to the primary winding of the transformer and an output voltage rectified and smoothed by a secondary-side rectifying-and-smoothing circuit having a rectifier diode and a smoothing capacitor is outputted. The switching power-supply device includes: a transient state detection circuit, which detects a transient state and outputs a soft-drive instruction signal; and a drive circuit which turns on-and-off the switching element in a soft-drive operation, in which a charging speed of a gate voltage at a time of passing a gate threshold voltage is delayed as compared to a normal operation, in a case where the soft-drive instruction signal is inputted.

Abstract: A selected-parameter adaptively switched power conversion system, for example, includes a counter for determining a period of an output oscillation a power supply switch, where the output oscillation starts when an output current generated by stored power of the power supply coil decays substantially to zero. An event generator for generating a switching delay event in response to the determined output oscillation period and generates a switching delay event in response to a determination of a phase of the output oscillation.

Abstract: An integrated circuit includes: an inductor; a switching element connected to the inductor in series; an oscillator, of which an oscillation frequency is variable; a control unit, which controls the oscillation frequency of the oscillator based on a signal according to an output voltage of a switching power-supply device; a drive signal generating unit, which generates a drive signal used for controlling the switching element based on an output of the oscillator; a drive circuit, which drives the switching element based on the drive signal generated by the drive signal generating unit; and an on-period intermittent control unit, which intermittently performs on-period extension control in which an on-period of the switching element is set to be longer than an on-period based on the drive signal in a state where the oscillation frequency is controlled not to be fixed by the control unit.

Abstract: A leakage current detection circuit includes a driving voltage detection unit that detects a cut-off point of a driving voltage regulated through a driving voltage switch, a leakage current detection unit that detects a leakage current of the driving voltage switch after cutting off of the driving voltage, generates a leakage detection signal when a driving voltage related to the leakage current exceeds a reference detection voltage and a driving voltage control unit that turns off the driving voltage switch at a cut-off point of the driving voltage to cut off the driving voltage and maintain the driving voltage switch in an off state when the leakage detection signal is received. The leakage current detection circuit detects a leakage current passing through the driving voltage switch when abnormal operation of a light emitting diode light apparatus occurs, and keeps the driving voltage switch in an off state during cutoff periods to prevent burning of the drive voltage switch.

Abstract: A voltage detecting circuit used with a switching converter. The switching converter having an energy storage component, a first power switch and a second switch. The voltage detecting circuit has a sample and hold circuit configured to sample and hold the voltage at the connection node of the energy storage component and the first power switch when the first power switch is OFF and the second power switch is ON; and an average circuit configured to average the sampled voltage during a switching period to generate a detecting signal in proportional to the output voltage of the switching converter.

Abstract: In one embodiment, an undervoltage protection circuit for a switching power supply can include: (i) an undervoltage detection circuit that determines whether an input voltage of the switching power supply is in an undervoltage state; (ii) a selection circuit configured to select a first or a second control signal to be provided as a main control signal to a control circuit; (iii) the control circuit being configured, in response to the main control signal being the first control signal, to control a switching operation of a power transistor in the switching power supply such that an output voltage of the switching power supply is maintained as substantially stable; and (iv) the control circuit being configured, in response to the main control signal being the second control signal, to control the switching operation of the power transistor to reduce an input power of the switching power supply.

Abstract: An object is to suppress deterioration of a high-voltage side battery regardless of the magnitude of a load current. Provided is a control device of a DC-DC converter that is constituted by a primary side circuit that is electrically connected between an input side and a transformer, and a secondary side circuit that is electrically connected between an output side and the transformer. The control device includes a command generating unit 325 that sets an output current limiting value to a predetermined value on the basis of a detected input voltage, a duty generating unit 330 that calculates a duty configured to turn ON/OFF a switching element on the basis of the output current limiting value and a detected output current, and a switching signal generating unit 335 that generates a switching signal on the basis of the duty. The duty generating unit 330 generates the duty so that an output current is limited to the output current limiting value or less.

Abstract: In a switching power supply device, a voltage of a counter electromotive force induced in a drive winding as a high side switching element is turned off is output to a ZT terminal of a switching control IC, and thus an OUT terminal of the switching control IC is brought to a high level, and thus a low side switching element is turned on. A constant current circuit charges a capacitor with a constant current through a voltage at the OUT terminal. A comparator in the switching control IC inverts the voltage at the OUT terminal to a low level upon a voltage at an IS terminal exceeding a voltage at an FB terminal. Thus, an on time of the low side switching element is controlled in accordance with a voltage output to the FB terminal, and an output voltage Vo is turned into a constant voltage.

Abstract: A detection circuit for converting a control signal while maintaining electrical isolation between a first ground and a second ground. The detection circuit includes a first input configured to receive the control signal; a gate signal input configured to receive a gate signal; a transformer; an isolator; a rectifier; and an output electrically connected to the rectifier, the output configured to output the converted control signal. The transformer is configured to receive the control signal from the first input, transform the control signal into a transformed control signal, and output the transformed control signal. The isolator is configured to receive the gate signal from the gate signal input, and control the transformer in response to the gate signal. The rectifier is configured to receive the transformed control signal from the transformer, and convert the transformed control signal to a converted control signal.

Abstract: The present invention discloses a power supply circuit for driving an LED lamp and a power supply method. The power supply circuit is constituted by an AC-DC converter by adopting DCM-DCM. Also, the power supply circuit adopts a valley fill circuit to reduce rippling of output current and adopts the DCM-DCM to stabilize a link voltage, thereby realizing a power factor correction circuit having two-stage structures. Thus, an input voltage of the flyback converter may be improved, and a high reverse voltage may be applied.

Abstract: A controller of a power converter with adjustable jitter amplitude includes a feedback pin, a logic circuit, an auxiliary pin, and a current sensing pin. The feedback pin is used for receiving a feedback voltage from a secondary side of the power converter. The feedback voltage corresponds to an output voltage of the secondary side of the power converter. The logic circuit is used for generating a jitter signal according to a clock, the feedback voltage, and a first resistor. The auxiliary pin is used for receiving a voltage corresponding to an auxiliary winding of the power converter. The current sensing pin is used for generating a detection voltage according to a current flowing through a primary side of the power converter. The voltage, the jitter signal, and the detection voltage determine turning-on time of the primary side of the power converter.

Abstract: A power supply device including a switch arrangement including switches for generating a square wave output, a switch control arrangement for controlling the switch arrangement, a resonator tank, a rectifier circuitry for rectifying in an output from the tank, and a burst mode operation arrangement configured to facilitate a standby mode of the power supply and including a burst mode restriction arrangement for receiving and evaluating a first feedback parameter associated with a switch of the switch arrangement, the burst mode operation arrangement further receiving and evaluating a second feedback parameter indicative of the output voltage of the power supply device, and being configured to disable and enable the burst mode feature based on the evaluation of both the first feedback parameter and second feedback parameter by controlling an output from the burst mode operation arrangement.

Abstract: A regulator control circuit includes a switch control signal generator to generate a switch control signal and a soft start circuit to generate a soft start signal for use by the switch control signal generator. The soft start circuit includes a soft start controller and a decreasing circuit to decrease the soft start signal in response to the soft start controller. The soft start controller may comprise a non-regulation detector to detect a non-regulation condition. Embodiments include decreasing the soft start signal in response to a non-regulation condition lasting a predetermined time, detecting the non-regulation condition in response to a maximum duty cycle of the regulator switch, generating a soft start level indicator to control decreasing the soft start signal, and maintaining the soft start signal at a predetermined relationship with respect to a feedback signal.

Abstract: Disclosed are a voltage waveform detector, a power controller and a control method used therein, adaptive for a switched-mode power supply having a power switch and an inductive device. A disclosed power controller has a voltage waveform detector and a constant-current control unit. The voltage waveform detector estimates a discharge time of the inductive device when the power switch is turned off. In the voltage waveform detector, a differential capacitor is coupled between an input node of a comparator and a feedback node, at which the feedback voltage corresponds to a reflection voltage of the inductive device. The constant-current control unit integrates a current-detection signal over the discharge time to control a maximum output current of the switched-mode power supply.

Abstract: According to an embodiment, an LED current control apparatus controls conduction of a switching transistor which is connected to a primary winding of a flyback convertor. The LED current control apparatus includes a pseudo sine wave generation unit, a synchronous control unit, a first comparator, a switch control unit, a crest value correction unit, and a pulse monitor control unit.

Abstract: A switch mode power supply (SMPS) system includes a rectifying circuit for coupling to an AC input voltage and a transformer having a primary winding for coupling to the rectifying circuit and a secondary winding coupled to the primary winding. The system also has a power switch coupled to the primary winding and a control circuit coupled to the power switch. The control circuit is configured to control current flow in the primary winding such that an envelop waveform formed by peak points of current pulses are in phase with the magnitude of the AC input voltage. Moreover, the SMPS system is configured to provide a constant average output current.

Abstract: A system configured to provide current to power a solid-state light emitting diode in accordance with a dimming level, wherein the dimming level corresponds to an amount of light provided from the solid-state light emitting diode. The system includes a transformer and a switch. The transformer includes a coil. The transformer is configured to receive a first current. The coil is configured to, based on the first current, output a second current to power the solid-state light emitting diode. The switch is configured to, based on a dimming level that corresponds to the amount of light provided from the solid-state light emitting diode of the system, bleed a portion of the second current out of the coil to a ground reference in order to divert the portion of the second current from being supplied to the solid-state light emitting diode.

Abstract: An isolated switching mode power supply, having: a transformer having a primary winding, a secondary winding and a third winding; a current limit comparator configured to provide a current limit signal based on the current sense signal and the peak current signal; a logic circuit configured to provide a logic control signal based on the frequency control signal and the current limit signal; a startup control circuit configured to generate a startup control signal based on the current sense signal; a load detecting circuit configured to provide a load detecting signal based on the second feedback signal and the switching signal; and a selector configured to provide the logic control signal or the startup control signal based on the load detecting signal.

Abstract: A method can be used for controlling the switching operation of a switching power converter that includes a semiconductor switch coupled in series to an inductor. The switching power converter consumes an input current from a power supply and provides an output current to a load. In each switching cycle a switch-on time instant is detected for the semiconductor switch. The semiconductor switch is closed thus enabling, at the detected switch-on time instant, the input current passing through the semiconductor switch. The semiconductor switch is opened after a desired on-time, during which the input current rises from zero to a peak value, has passed. A time interval is detected, in which the instantaneous output current is not zero. A first value that represents the peak of the input current is obtained during the on-time.

Abstract: The present invention discloses a power supply circuit for driving an LED lamp and a power supply method. The power supply circuit is constituted by an AC-DC converter by adopting DCM-DCM. Also, the power supply circuit adopts a valley fill circuit to reduce rippling of output current and adopts the DCM-DCM to stabilize a link voltage, thereby realizing a power factor correction circuit having two-stage structures. Thus, an input voltage of the flyback converter may be improved, and a high reverse voltage may be applied.

Abstract: A power conversion system with adjustable frequency includes an electric transformer, a pulse width modulation driving controller, a switching transistor, a first and second voltage division resistors connected in series, an output diode and an output capacitor. The electric transformer receives the input power and generates the sensing current and induced current. The sensing current flows through the first and second voltage division resistors to generate the feedback signal. The induced current flows through the output diode and output capacitor to generate the output voltage to supply the load. The pulse width modulation driving controller determine whether the loading state of the load based on the feedback signal, and change the switching frequency according to the loading state and the input power, thereby increasing the whole efficiency of the power conversion system and achieving the aim of dynamically adjusting the optimal frequency.

Abstract: A method for controlling voltage crossing a power switch of a switched-mode power converter includes the steps of: controlling a switch frequency of the power switch of the switched-mode power converter to a first frequency as activating the switched-mode power converter; and then changing the switch frequency of the power switch to a second frequency after the switched-mode power converter is activated for a predetermined time; wherein the first frequency is lower than the second frequency.

Abstract: A power conversion system has a power converter configured to receive an input voltage signal, convert the input voltage to an output voltage signal, and provide the output voltage signal to a load and a closed loop compensator configured to receive the output voltage signal and a reference voltage signal, the closed loop compensator configured to transmit an error signal indicative of a difference between the output voltage signal and the reference voltage signal. The power conversion system further has a pulse with modulator configured to receive the error signal and modulate a control signal with the error signal to control the output voltage signal, the pulse width modulator configured to transmit the control signal to the power converter and logic configured to receive the error signal and control the closed loop compensator based upon the error signal.

Abstract: An inverter and driving method of the inverter are disclosed. The inverter includes an active clamp forward (ACF) converter and a flyback converter. One of a forwarding operation of delivering current from a primary side to a secondary side by using the ACF converter and a backwarding operation of delivering current from the secondary side to the primary side by using the flyback converter is selected to generate a rectified AC.