Abstract: System and method for regulating an output voltage of a power conversion system. The system includes an error amplifier coupled to a capacitor. The error amplifier is configured to receive a reference voltage, a first voltage, and an adjustment current and to generate a compensation voltage with the capacitor. The first voltage is associated with a feedback voltage. Additionally, the system includes a current generator configured to receive the compensation voltage and generate the adjustment current and a first current, and a signal generator configured to receive the first current and a second current. The signal generator is further configured to receive a sensing voltage and to generate a modulation signal. Moreover, the system includes the gate driver directly or indirectly coupled to the signal generator and configured to generate a drive signal based on at least information associated with the modulation signal.

Abstract: The invention includes a high-voltage power supply connected, by a network input, to an AC network of frequency Fr, with n phases, and providing a high DC output voltage at at least one HV output. The power supply includes a single-phase high-voltage conversion module per phase of the network having a current rectification circuit connected, by a single-phase input of the conversion module, to a respective phase of the network and, by a rectified-current output, to a switching circuit having at least one switching transistor for switching the rectified current at a frequency Fd and p secondary HV circuits, each providing a secondary, p being an integer greater than or equal to 1, j being the rank of the secondary HV circuit ranging between 1 and p. A control and regulation unit for the power supply comprises a control circuit per conversion module.

Abstract: An example controller includes a comparator coupled to receive a feedback signal representative of an output of the power converter. A counter is coupled to receive an output of the comparator and a feedback sampling signal. The counter is coupled to sample the output of the comparator in response to the feedback sampling signal. A state machine is coupled to receive a feedback time period signal. The state machine is coupled to control switching of the power converter according to one of a plurality of operating conditions in response to the counter and the feedback time period signal. A period of the feedback time period signal is substantially greater than a period of the feedback sampling signal. The state machine is coupled to be updated in response to the feedback time period signal.

Abstract: A power supply circuit for an electrical appliance, including a turning-on stage configured for determining a transition from a turned-off state, in which the power supply circuit is off and does not supply electric power, to a turned-on state of the power supply circuit. The turning-on stage includes a transducer of the remote-control type configured for triggering the transition in response to the reception of a wireless signal. In some embodiments, operating power is transmitted from a remote controller to a control circuit of the electronic equipment, such that the electronic equipment can be turned on remotely but draws zero standby power.

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal and a second controller terminal. The system controller is configured to receive at least an input signal at the first controller terminal, and generate a gate drive signal at the second controller terminal based on at least information associated with the input signal to turn on or off a transistor in order to affect a current associated with a secondary winding of the power conversion system. The system controller is further configured to, if the input signal is larger than a first threshold, generate the gate drive signal at a first logic level to turn off the transistor.

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal, a second controller terminal and a third controller terminal. The system controller is configured to receive an input signal at the first controller terminal and turn on or off a switch based on at least information associated with the input signal to adjust a primary current flowing through a primary winding of the power conversion system, receive a first signal at the second controller terminal from the switch, and charge a capacitor through the third controller terminal in response to the first signal.

Abstract: The present invention discloses CVCC circuits and methods with improved load regulation for an SMPS. In one embodiment, the CVCC can include: a voltage feedback circuit to generate an output voltage feedback signal; a current feedback circuit to generate an output current feedback signal; a control signal generating circuit that receives the output voltage feedback signal and the output current feedback signal, and generates a constant voltage/constant current control signal; a first enable signal generating circuit that compares a first reference voltage and the constant voltage/constant current control signal to generate a first enable signal; and a PWM controller that generates a PWM control signal based on the constant voltage/constant current control signal to control a main switch of the flyback SMPS.

Abstract: Provided is a current sensing signal comparing device and current sensing signal comparing method. The current sensing signal comparing device includes a current sensing circuit for detecting a current signal of a switching circuit and thereby generating a current sensing signal, a control unit for outputting a control signal, and a compensating circuit for compensating the current sensing signal according to the control signal. The compensated current sensing signal is compared with a constant current reference signal in order to issue a constant current control signal. The device can also be provided to configure the compensating circuit to compensate the constant current reference signal, such that the current sensing signal is compared with the compensated constant current reference signal in order to issue a constant current control signal.

Abstract: A resonant power converting circuit is provided, which includes a resonant converting unit, a control unit, a current detecting unit and a frequency modulation unit. The control unit outputs switching signals to the resonant converting unit to adjust an output thereof. The current detecting unit is configured to detect an output current of the resonant converting unit. The frequency modulation unit may adjust a lowest switching frequency of the control unit according to the detected output current so as to increase a gain of the resonant converting unit and an output stability of the resonant converting unit.

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

Abstract: An example switched mode power supply includes a timer, a threshold adjust circuitry, a comparator, and a control circuitry. The timer times a duration between crossings of a phase-dimmed signal across a first threshold. The threshold adjust circuitry adjusts a second threshold representative of a desired output of the switched mode power supply, where the second threshold is adjusted responsive to the timed duration between crossings. The comparator compares a feedback signal with the second threshold and generates a comparison result. The control circuitry controls switching of a power switch responsive to the comparison result to regulate the output of the switched mode power supply.

Abstract: A power source device includes: a transformer; a switching section driving a primary side of the transformer; and a controller capable of performing a switching operation on driving of the switching section for controlling an output of a secondary side of the transformer. The device detects a drive frequency for the switching section in the switching operation, and switches the drive frequency so as not to be a frequency in a prescribed range when the detected drive frequency reaches a threshold.

Abstract: A two-switch Flyback power converter is disclosed. The two-switch Flyback power converter comprises a transformer, a first switch, a second switch, and a control circuit. The transformer includes a primary-winding and a secondary-winding. The primary-winding has a first winding and a second winding. The first switch is coupled to switch the first winding. The second switch is coupled to switch the first winding and the second winding. The control circuit generates a first-drive signal and a second-drive signal to control the first switch and the second switch for switching the transformer and regulating an output of the two-switch Flyback power converter. The two-switch Flyback power converter with less capacitance of the bulk capacitor or bulk capacitor-less can reduce the voltage ripples at the output voltage for cost saving.

Abstract: The present invention relates to a constant voltage constant current (CVCC) controller, and associated control methods. In one embodiment, a CVCC controller for a flyback converter can include: (i) a current controller configured to generate an error signal by comparing an output current feedback signal against a reference current; (ii) a voltage controller configured to receive an output voltage feedback signal and a reference voltage, and to generate a control signal; (iii) a selector configured to control the flyback converter to operate in a first or a second operation mode based on the control signal, and to further generate a constant voltage or a constant current control signal based on the error signal; and (iv) a pulse-width modulation (PWM) controller configured to generate a PWM control signal to control a main switch, and to maintain the output voltage and/or current of the flyback converter as substantially constant.

Abstract: Some of the embodiments of the present disclosure provide an apparatus comprising a voltage sensor circuit configured to generate a voltage feedback signal indicative of an output voltage of the apparatus, a current sensor circuit configured to generate a current feedback signal indicative of a load current of the apparatus, a converter configured to receive the current feedback signal, and generate a fault signal that is indicative of a fault condition associated with the load current, and an optocoupler configured to receive the voltage feedback signal and the fault signal, and generate a feedback signal that is indicative of the output voltage and indicative of the fault condition. Other embodiments are also described and claimed.

Abstract: A current reference generating circuit including a first multiplier module, configured to receive a rectified voltage waveform signal of a switch mode power supply and an output signal generated by an average current loop, and to generate a sinusoidal half-wave signal having the same frequency and phase as the rectified voltage waveform signal, the sinusoidal half-wave signal varies with the output signal generated by the average current loop. A second multiplier module, configured to receive the sinusoidal half-wave signal and a control signal to generate a pulse signal. An average current loop for comparing the average of the pulse signal to a predetermined average current loop reference signal. The circuit can generate a self-adapted reference signal that follows the primary-side current signal of main circuit of the switch mode power supply, which is then supplied to the constant current switch mode power supply control circuit with high power factor.

Abstract: A switching mode power supply, and a primary-side controlled PFM converter using the primary-side regulated PFM controller are discussed. In present embodiment, the primary side cycle by cycle switch peak current is no longer a constant. The time detector is added to monitor the waveform of primary-side sample voltage and then generate the duty cycle. The transfer function should be selected to satisfy a specific relationship of switching frequency and switch peak current against with output loading current. The new design shows higher switching frequency but lower value of switch peak current at light load condition. This resolves the audible noise and poor transient response issue from the prior art PFM controller.

Abstract: An example integrated circuit for use in a power supply includes a feedback terminal, a controller and a clamp. The feedback terminal is to be coupled to receive a feedback signal that is representative of a bias voltage across a bias winding of the power supply. The controller is to be coupled to control switching of a power switch included in the power supply in response to the feedback signal. The clamp is coupled to clamp the feedback terminal to a voltage for at least a time that the bias voltage is negative with respect to an input return of the power supply.

Abstract: A power factor correction device, and a controller and a total harmonic distortion (THD) attenuator used by same. The power factor correction device comprises a converter and a controller (320) connected to the converter to obtain an input voltage. The controller (320) comprises a THD attenuator (407) for automatic THD optimization. The converter comprises an input current detection resistor (3R8), a power switch tube (3NMOS) and an output circuit. The input current detection resistor (3R8), the power switch tube (3NMOS) and the output circuit form a feedback control loop to maintain a constant output voltage. A THD optimization function is built in the device so that the entire device is capable of being accurately offset to a designed voltage so as to be used for THD optimization, thereby dispensing with external manual adjustment and overcoming internal technical deviations while achieving high consistency.

Abstract: An alternating parallel flyback converter with alternated master and slave circuit branches is provided. The flyback converter includes a master flyback circuit branch, a slave flyback circuit branch connected with the master flyback circuit branch in parallel, and a controller. The controller controls the operation of each of the flyback circuit branches based on the current and the voltage at the output terminal of the flyback converter. The master flyback circuit branch operates continuously while the slave flyback circuit branch only operates when the output power of the flyback converter is higher than a threshold. The master flyback circuit branch and the slave flyback circuit branch are periodically alternated, and in particular, through zero crossing of the power. With the flyback converter of the present invention, the reliability and the service life of the converter can be improved.

Abstract: A control circuit and method are provided for a flyback converter converting an input voltage to an output voltage, to compensate for an entry point of a burst mode of the flyback converter, so that the entry point is not affected by the input voltage, and audible noise resulted from a higher input voltage is reduced without impacting the light load efficiency of the flyback converter.

Abstract: A flyback converter uses primary side sensing to sense the output voltage for regulation feedback. Such sensing requires a predetermined minimum duty cycle even with very light load currents. Therefore, such a minimum duty cycle may create an over-voltage condition. In the flyback phase, after a minimum duty cycle of the power switch at light load currents, a synchronous rectifier turns off approximately when the current through the secondary winding falls to zero to create a discontinuous mode. If it is detected that there is an over-voltage, the synchronous rectifier is turned on for a brief interval to draw a reverse current through the secondary winding. When the synchronous rectifier shuts off, a current flows through the primary winding via a drain-body diode while the power switch is off. Therefore, excess power is transferred from the secondary side to the power source to reduce the over-voltage so is not wasted.

Abstract: Embodiments of circuits and methods for a switching mode power supply are described in detail herein. In one embodiment, a switching mode power supply includes a transformer having a primary winding and a secondary winding to supply power to a load, a feedback circuit that generates a feedback signal that varies in relation to the load on the secondary winding, a switching circuit coupled to the primary winding to control current flow through the primary winding, and a control circuit coupled to the switching circuit to control the on/off status of switching circuit in response to the feedback signal and the current flow through the primary winding. The control circuit comprises a spectrum shaping circuit configured to generate a spectrum shaping signal in response to the feedback signal. The spectrum shaping signal can then be used to regulate the switching frequency and the spectrum shaping range.

Abstract: A capacitor discharging circuit and a converter are disclosed. The converter comprises: a capacitor connected between the live line and null line of an AC power input terminals, a conversion module coupled to the capacitor and comprising an energy storage component at least, an energy transfer unit coupled with the energy storage component and the capacitor, an AC power-off detecting unit and a control unit; wherein the energy transfer unit comprises a switch device; when AC power is disconnected, the AC power-off signal triggers the control unit to output a switch driving signal, controlling the operation of the energy transfer unit to transfer the energy stored in the capacitor to the energy storage component to discharge the capacitor.

Abstract: The present invention relates to an electronic circuit with which input voltages at an input of the circuit are converted into higher output voltages at an output of the circuit, whereby the voltage conversion already starts at low voltages at the input. According to the present invention, the DC converter circuit for the generation of an output voltage from an input voltage (Vin) comprises a transformer (Tr) with a first primary winding (1) that can be connected to the input voltage (Vin) via a first transistor (T1) that is connected in series, and a second primary winding (2) that can be connected to the input voltage (Vin) via a second transistor (T2) that is connected in series.

Abstract: A switching mode power supply (SNIPS) includes a rectifying unit transforming AC power input from outside to DC power, a main transformer transforming and outputting the rectified DC power, a pulse width modulation control unit controlling output voltage by applying a pulse signal to a primary winding of the main transformer, and a feedback control unit controlling an output signal of the pulse width modulation control unit by detecting output voltage of the main transformer, including: a first state transform unit, including: a second photo diode; and a second photo transistor included between an AC power input unit and the pulse width modulation control unit to form a photo coupler with the second photo diode, and a second state transform unit, including: a comparator connected to a secondary winding of the main transformer to apply the output voltage and reference voltage to an inverting terminal and a noninverting terminal, and compare the output voltage with the reference voltage and output the voltage t

Abstract: The invention relates to a method for operating a switched mode power supply as an isolating transformer. According to said method, magnetic energy is stored in the core of a transformer during a storage stage via a primary coil that is connected to an intermediate circuit current and the stored magnetic energy is delivered to a load in a subsequent discharge phase, for the most part by means of a secondary coil, a small part of said magnetic energy being discharged on the primary side. The energy that is discharged on the primary side charges a capacitor in such a way that the capacitor current is always held above the secondary current multiplied by the transmittance ratio of the transformer.

Abstract: This relates to detecting unwanted couplings between a protected terminal and other terminals in an integrated controller of a power supply. Offset and clamp circuitry may apply a positive or negative offset voltage and clamp current to one or more terminals of the controller. In the event that a terminal having the offset voltage and clamp current is accidentally coupled to the protected terminal, the offset voltage and clamp current may be applied to the protected terminal. The protected terminal may be coupled to a fault detection circuitry operable to detect a fault signal at the protected terminal. The fault detection circuitry of the controller may cause the power supply to shut down in response to a detection of the fault signal at the protected terminal or may cause the power supply to shut down in response to a detection of a predefined threshold number of cycles in which the fault signal is detected.

Abstract: The prevent invention provides an AC-DC flyback converter and a loop compensation method thereof. The AD-DC flyback converter comprises an isolating transformer, a power switch, and a feed control module. The feed control module includes a compensating circuit, a voltage buffer, and an error amplifier having a first resistor and a second resistor, and a pulse width modulation controller. With the AC-DC flyback converter and the loop compensating method, the system stability can be improved and the loop bandwidth can be reduced.

Abstract: The present invention relates to a converter, a switch controller controlling switching operation of a power switch in the converter, and a switch control method. An exemplary embodiment of the present invention generates a reference current corresponding to an output current of the converter and generates a control voltage that depends on the reference current. The exemplary embodiment controls an increase or a decrease of the control voltage and determines a switching frequency of the power switch according to the control voltage. The exemplary embodiment controls on-time of the power switch using a reference voltage determined according to a control current that depends on the reference current.

Abstract: A switching amplifying method or a switching amplifier for obtaining one or more than one linearly amplified replicas of an input signal, is highly efficient, and does not have the disadvantage of “dead time” problem related to the class D amplifiers. Said switching amplifying method comprises the steps of: receiving the input signal; pulse modulating the input signal for generating a pulse modulated signal; switching a pulsed current from a direct current (DC) voltage according to the pulse modulated signal; conducting said pulsed current positively or negatively to a filter according to the polarity of the input signal; filtering said pulsed current positively or negatively conducted to the filter for outputting an output signal by the filter.

Abstract: An example controller for a primary side control power converter includes a feedback circuit, a driver circuit, and an adjustable voltage reference circuit. The feedback circuit compares a feedback signal representative of a bias winding voltage of the power converter with a voltage reference. The driver circuit outputs a switching signal having a switching period to control a switch to regulate an output of the power converter in response to the feedback signal and enables or disables a switching period based on the output of the feedback circuit. The adjustable voltage reference circuit adjusts the voltage reference by a first amount in response to a first number of disabled switching periods indicating a first load condition at the output of the power converter and by a second amount in response to a second number of disabled switching periods indicating a second load condition at the output of the power converter.

Abstract: According to an example embodiment, a controller for a Switched Mode Power Supply having opto-coupler-based feedback from secondary to primary side, is disclosed, in which the optocoupler current varies inversely with the output voltage over a voltage control range. The converter is thereby enabled to consume less power than do conventional converters, when in lower-power standby mode. Also disclosed are low-voltage startup and over-voltage protection arrangements combined with such a controller. Corresponding methods are also disclosed.

Abstract: Consistent with an example embodiment, a circuit comprises a power factor correction stage having a DC input, a ground input, a DC output and a ground output. The circuit further includes a capacitor; a diode; and a discharge circuit. A first terminal of the diode is connected to an input of the power factor correction stage, a second terminal of the diode is connected to the first plate of the capacitor; and the second plate of the capacitor is connected to the other input of the PFC stage. The discharge circuit is connected to the capacitor and is configured to discharge the capacitor such that it contributes to the output of the PFC stage when the level of a signal at the input of the PFC stage falls below a threshold value.

Abstract: A power converter control circuit includes a ramp signal circuit, a blanking circuit, and a pulse driver circuit. The ramp signal circuit provides a ramp signal in response to a power converter feedback signal and an enable signal. The blanking circuit provides a blanking signal in response to the ramp signal and a clock signal. The blanking signal is provided when both the ramp signal is increasing in value and the enable signal indicates a light load operating condition. The pulse driver circuit provides a power switch control pulse in accordance with the clock signal and in the absence of the blanking signal.

Abstract: System and method are provided for regulating a power converter. The system includes a signal processing component configured to receive a first input signal and a second input signal, process information associated with the first input signal and the second input signal, and output a drive signal to a switch based on at least information associated with the first input signal and the second input signal. The first input signal is associated with at least a feedback signal related to an output voltage of the power converter. The second input signal is associated with at least a primary current flowing through a primary winding of the power converter. The signal processing component is further configured to change a peak value of the primary current within a first predetermined range, and change the switching frequency of the power converter within a second predetermined range.

Abstract: A switch-mode power supply (SMPS) is provided. When the switch power of the SMPS turns on, the inductor current of the SMPS may flow through an inductor current sensing circuit which then provides a sensing voltage. An apparatus for compensating the inductor current peak receives a reference voltage and the sensing voltage as inputs and outputs a compensation voltage. The compensation voltage is combined with the reference voltage and/or the sensing voltage and is provided to a first comparator. The result keep 7t as 7s is provided to the logic control circuit coupled to the gate of the power switch after being driven by a driver circuit. The actual inductor current peak is kept identical with the reference current, which effectively controls the inductor current peak, thereby protecting the SMPS.

Abstract: A method of operating a DC-DC converter according to the current mode control is provided. A current measuring signal for determining a turn-off time of a converter switching element is supplied to a PWM controller and a voltage that is proportional to the current measuring signal is compared by a comparator to a reference voltage. When the reference voltage is exceeded, the converter switching element is turned off.

Abstract: An example controller for a power converter includes a track and hold circuit, a sample and hold circuit, and drive logic. The track and hold circuit receives a signal from a terminal of the controller that is representative of an output voltage of the power converter. The track and hold circuit includes a first capacitor that provides a first voltage that tracks the signal and then holds the first voltage. The sample and hold circuit samples the first voltage when the first voltage is held on the first capacitor. The sample and hold circuit includes a second capacitor coupled to hold a second voltage representative of the first voltage after a sample period, where the second capacitor has a capacitance value larger than that of the first capacitor. The drive logic controls the first switch to regulate an output of the power converter in response to the second voltage.

Abstract: An example controller for a power converter includes a feedback sampling circuit, drive logic and a false sampling prevention circuit. The feedback sampling circuit is coupled to sample a feedback signal received from a terminal of the controller and to generate a sample signal representative of a value of the feedback signal. The drive logic is coupled to the feedback sampling circuit and coupled to control the power switch to regulate an output of the power converter in response to the sample signal. The false sampling prevention circuit is coupled to receive a sampling complete signal that indicates when the sampling of the feedback signal is complete. The false sampling prevention circuit is further coupled to the drive logic to extend the off time of the power switch until the sampling complete signal indicates that the sampling of the feedback signal by the feedback sampling circuit is complete.

Abstract: Methods and apparatuses are disclosed for generating a temperature independent current limit. The value of the temperature independent current limit may be determined based in part on an error signal representative of a difference between an actual output value and a desired output value of a power converter. When the error signal is below a lower threshold voltage, the temperature independent current limit may be set to a first value. When the error signal is above an upper threshold voltage, the temperature independent current limit may be set to a second, higher value. When the error signal is between the lower threshold voltage and the upper threshold voltage, the temperature independent current limit may change linearly with the error signal. The error signal may be adjusted to compensate for changes in the system caused by a change in temperature.

Abstract: A drive circuit drives a normally-on high-side switch Q1 and a normally-off low-side switch Q2 that form a series circuit connected in parallel with a DC power source. The drive circuit includes a controller 10 that outputs a control signal to turn on/off the high- and low-side switches, a rectifier D2 having a first end connected to a connection point of the high- and low-side switches, a capacitor C2 that is connected to a second end of the rectifier and a first end of the DC power source and serves as a power source for the controller, and a driver (A1, AND1, Q3, Q4) that turns on/off the high- and low-side switches according to the control signal from the controller and a voltage from the capacitor.

Abstract: A method of operation for flyback power converter includes operating a controller of the flyback power converter in a regulation mode when a control signal is below a first threshold. The control signal is provided as an input to a terminal of the flyback power converter. When the control signal is below a second threshold and above the first threshold, the controller is operated in a limiting mode. The controller is operated in an external command mode when the control signal is below a third threshold and above the second threshold. Lastly, when the control signal is above the third threshold, the controller is operated in a protection mode.

Abstract: An input voltage detection unit detects whether an AC input voltage is the voltage of a 100V system or of a 200V system. In response, a frequency decreasing gain setting unit switches between frequency decreasing gain characteristics relative to load factors. The frequency decreasing gain characteristics are established so that the initiation of a decrease in a feed back signal in the 100V system is earlier than that in the 200V system. By switching the frequency decreasing gain characteristics based on an AC input signal, the characteristics, in which a decrease in a feed back signal in the 200V system is earlier than that in the 100V system, are cancelled to allow load factors, at each of which a power supply operation frequency reaches the audible region, to be approximately the same to enable a vibration isolating measure to be independent of the AC input voltage.

Abstract: A control circuit of the power converter according to the present invention comprises a feedback circuit, an output circuit and an adaptive clamping circuit. The feedback circuit generates a feedback signal in accordance with an output of the power converter. The output circuit generates a switching signal in accordance with the feedback signal for regulating the output of the power converter. The adaptive clamping circuit limits the level of the feedback signal under a first level for a first load condition. The feedback circuit determines a slew rate of the feedback signal for increasing the level of the feedback signal from the first level to a second level. The adaptive clamping circuit is disabled and the level of the feedback signal can be increased to the second level for a second load condition.

Abstract: In one embodiment, a quasi-resonant power supply controller is configured to select particular valley values of a switch voltage to determine a time to enable a power switch. The valleys values are selected responsively to a range of values of a feedback signal.

Abstract: A current reference generating circuit including a first multiplier module, configured to receive a rectified voltage waveform signal of a switch mode power supply and an output signal generated by an average current loop, and to generate a sinusoidal half-wave signal having the same frequency and phase as the rectified voltage waveform signal, the sinusoidal half-wave signal varies with the output signal generated by the average current loop. A second multiplier module, configured to receive the sinusoidal half-wave signal and a control signal to generate a pulse signal. An average current loop for comparing the average of the pulse signal to a predetermined average current loop reference signal. The circuit can generate a self-adapted reference signal that follows the primary-side current signal of main circuit of the switch mode power supply, which is then supplied to the constant current switch mode power supply control circuit with high power factor.

Abstract: A frequency jittering control circuit for a PFM power supply includes a pulse frequency modulator to generate a frequency jittering control signal to switch a power switch to generate an output voltage. The frequency jittering control circuit jitters an input signal or an on-time or off-time of the pulse frequency modulator to jitter the switching frequency of the power switch to thereby improve EMI issue.

Abstract: A multiple-output switching power supply unit includes: a voltage generating circuit Q1, Q2, T1a, 10a configured to generate a pulse voltage by intermittently interrupting a direct current power supply 1; a series resonance circuit including a current resonance capacitor Cri2, a primary winding P2 of a transformer T2, and a switching element Q3, the pulse voltage generated in the voltage generating circuit being applied to the series resonance circuit; a rectifying/smoothing circuit D2, C2 configured to rectify and smooth a voltage which is generated in a secondary winding S2 of the transformer, and thus to output a direct current output voltage; and a control circuit 11 configured to turn on and off the switching element based on the direct current output voltage.

Abstract: The present invention relates to a switch control circuit, a power factor corrector including the same, and a driving method thereof. According to an exemplary embodiment of the present invention, a turn-on time of a power switch is controlled according to a zero crossing voltage to sense a voltage of both terminals of the power switch, and a turn-off time of the power switch is controlled according to a feedback voltage corresponding to the output voltage. At this time, the switching frequency of the power switch is sensed by the zero crossing voltage and the switching frequency is restricted by a predetermined threshold frequency.