Abstract: A power converter controller asserts a leading edge signal when a leading edge of a voltage signal is detected. The voltage sense signal is representative of an input voltage of the power converter. A trailing edge signal is asserted when a trailing edge of the voltage signal is detected. A first state of a threshold signal is generated when the voltage sense signal is at or above an upper threshold and generating a second state of the threshold signal when the voltage sense signal is at or below a lower threshold. A conduction signal is updated in response to the leading edge signal, the trailing edge signal, and the threshold signal. The conduction signal is for controlling a switch coupled to regulate an output of the power converter.

Abstract: A control circuit of a power converter is provided. It comprises a voltage detection circuit detecting a reflected signal for generating a voltage-loop signal. A current detection circuit detects a current of a transformer for generating a current-loop signal. An oscillator generates an oscillation signal in accordance with an output load of the power converter. A PWM circuit generates a switching signal according to the voltage-loop signal, the current-loop signal and the oscillation signal for regulating an output of the power converter. A load detection circuit receives a detection signal through an signal-transfer device for increasing a switching frequency of the switching signal. The detection signal is generated once the output is lower than a low-voltage threshold. The oscillation signal determines the switching frequency of the switching signal. The control circuit reduces the voltage drop of the output when the output load is changed.

Abstract: A primary-only power supply enables transmission of a signal or message from the secondary side of an isolated power supply to the primary side. To enable robust detection of the message without interfering with primary side sensing for output regulation, a configurable impedance current path is configured between the primary winding and ground. The primary side controller controls the configurable impedance current path to have a relatively low impedance during the normal mode and a relatively high impedance during the messaging mode.

Abstract: Switching regulator methods and systems are provided for supplying output current at a regulated voltage level to a load. Upon determining that the output current is not below a predetermined current threshold, the regulator is operated in a continuous mode. The input voltage is monitored. If the input voltage is not below a first input threshold level, the system remains in continuous mode. Otherwise, the system enters a burst mode in which the switch mode power supply is turned OFF, thereby reducing transistor gate charge losses.

Abstract: A power control system includes a switching power converter and a controller. The controller is configured to detect an over-current condition of an inductor current in the switching power converter using at least one non-inductor-current signal. In at least one embodiment, the switching power converter does not have a resistor or resistor network to sense the inductor current. In at least one embodiment, the controller indirectly determines a state of the inductor current using at least one non-inductor-current signal. Potentially damaging inductor current values that are, for example, greater than a normal maximum value or at a value that causes a discontinuous conduction mode system to operate in continuous conduction mode represent exemplary inductor over-current conditions addressed by one embodiment of the power control system.

Abstract: A method for forming a sensor includes forming a base-region barrier in contact with a base substrate. The base-region barrier includes a monocrystalline semiconductor having a same dopant conductivity as the base substrate. An emitter and a collector are formed in contact with and on opposite sides of the base-region barrier to form a bipolar junction transistor. The collector, the emitter and the base-region barrier are planarized to form a level surface opposite the base substrate such that when the level surface is exposed to charge, the charge is measured during operation of the bipolar junction transistor.

Abstract: A soft-start switching power converter includes a voltage converting circuit and a soft-start circuit. The voltage converting circuit includes a transformer, and a first switch which includes a first terminal connected to the transformer, a second terminal providing a trigger signal, and a control terminal receiving a control signal, and which is controlled to switch between conduction and nonconduction, such that the transformer generates a feedback voltage. The soft-start circuit receives the trigger signal, generates the control signal according to the trigger signal, and determines whether or not to clamp the control signal at a preset voltage level based on the trigger signal.

Abstract: A controller for adjusting an output voltage of a power converter includes a gate control signal generation circuit, a feedback signal detection module, and a reference voltage generation module. The gate control signal generation circuit generates a gate control signal to a power switch of a primary side of the power converter according to a reference voltage and a plurality of signals corresponding to the primary side and a secondary side of the power converter. The feedback signal detection module generates a logic signal according to a combination corresponding to the plurality of signals. The reference voltage generation module generates the reference voltage to the gate control signal generation circuit according to the logic signal. The power switch adjusts the output voltage of the secondary side of the power converter according to the gate control signal.

Abstract: The embodiments disclosed herein describe a method of a controller to maintain a substantially constant average output current at the output of a switching power converter. In one embodiment, the controller uses a regulation voltage that corresponds to the primary peak current regulation level to regulate the average output current.

Abstract: The present invention is to provide a frequency jitter circuit and a method for generating frequency jitter. The frequency jitter circuit, comprising: an oscillating circuit, configured to generate an oscillating frequency output signal; a decoding circuit, configured to be controlled by said oscillating frequency output signal for generating several pulse output signals; a delay circuit, through which said oscillating frequency output signal is passed for generating a frequency jitter output signal that is delayed a period of time compared to said oscillating frequency output signal. Application of the invention into switched-mode power supply might reduce EMI average noise in the switched-mode power supply, and smooth energy spectrum density.

Abstract: In one embodiment, a method of controlling an AC-DC power converter, can include: (i) receiving, by a filter capacitor, a first branch current from an input current of the AC-DC power converter; (ii) receiving, by a power converting circuit, a second branch current from the input current; (iii) receiving, by the power converting circuit, a feedback signal that represents an output signal of the power converting circuit, and a triangular wave signal that is determined by the first branch current; (iv) generating a first conduction time based on the feedback signal such that the power converting circuit produces a first converting current; and (v) generating a second conduction time based on the triangular wave signal such that the power converting circuit produces a second converting current having a same absolute value as the first branch current.

Abstract: An insulated power supply apparatus includes an upper arm transformer which has a primary side coil and a secondary side coil, a lower arm transformer which has a primary side coil and a secondary side coil, and a power supply control section which has a voltage control switching element and an integrated circuit which turns on or off the voltage control switching element. At least one of the upper arm transformer and the lower arm transformer is adjacent to the power supply control section when viewing a surface of the substrate from a front thereof. An electric path transfers output voltage of the secondary side coil of the transformer adjacent to the power supply control section, to the integrated circuit. The integrated circuit turns on or off the voltage control switching element to perform feedback control so that the output voltage detected via the electric path reaches a target voltage.

Abstract: The present disclosure provides systems and methods for protecting a switch mode power supply (SMPS). An SMPS may include an input power connector, an input rectifier and filter, a transformer, an output rectifier and filter, and an output power connector. A control circuit may selectively generate a switching signal for driving the transformer based on a feedback signal and a protection signal generated by a protection circuit. The protection circuit may generate the protection signal with an asymmetric duty cycle oscillating between an enable state and an inhibit state. The protection signal may inhibit the control circuit from generating the switching signal when the protection signal is in the inhibit state. A detection circuit may receive the feedback signal and selectively force the protection signal to the enable state when the feedback signal indicates that an output voltage is too high.

Abstract: The present invention relates to a power supply for controlling current that uses a flyback converter for electrical insulation between a load line unit and the power supply for controlling current. In a transformer (a flyback converter) having a flyback structure in the present invention, disclosed is a device which expects a current of the second coil by sensing a current of the first coil of the transformer, and controls the current flowing through the load line unit. A level detector is included, which updates a duty time or an on-time of the switch by transferring a reset signal to an integrator and a second sampler in accordance with a cycle of an input power. As a result, it is possible to reduce power loss by increasing a power factor through the adjustment of the phase of the current of the load line unit and an input voltage.

Abstract: Aspects of the disclosure provide a power circuit to provide electric energy with control and protection for driving a load, such as a light emitting diode (LED) array, and the like. The power circuit includes a converter, a voltage feedback module, a current feedback module and a controller. The converter is configured to receive electric energy from an energy source and to deliver the electric energy for driving the load. The voltage feedback module is configured to generate a first feedback signal based on a voltage of the delivered electric energy. The current feedback module is configured to generate a second feedback signal based on a current of the delivered electric energy. The controller is configured to receive the first feedback signal and the second feedback signal, and to control the converter to receive and deliver the electric energy based on the first feedback signal and the second feedback 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: Systems and methods are provided for regulating a power conversion system. An example system controller includes a driving component and a detection component. The driving component is configured to output a driving signal to a switch associated with a first current flowing through a primary winding of a power conversion system, the switch including a first switch terminal related to a first voltage and a second switch terminal related to a second voltage, the driving signal being associated with a plurality of switching periods. The detection component is configured to receive an input signal associated with a difference between the first voltage and the second voltage, detect at least one valley of the input signal in magnitude during a detection period for the first switching period, and output a detection signal based on at least information associated with the input signal to affect the driving signal.

Abstract: A power delivery (PD) device includes: an AC/DC converter connected to an AC input, the AC/DC converter configured to change the AC input to a desired voltage value to be output in accordance with a first voltage changing control signal supplied from outside; and a DC/DC converter connected between an output of the AC/DC converter and a DC output, the DC/DC converter configured to change the output from the AC/DC converter to a desired voltage value to be output as a DC output in accordance with a second voltage changing control signal supplied from outside, wherein the AC/DC converter at a previous stage and the DC/DC converter at a subsequent stage are interlocked to change the output voltage to desired target voltage. There can be provided the PD device capable of delivering power with high power efficiency over the wide voltage ranges.

Abstract: The present invention is a switched-mode power supply for providing a stable output voltage. An excitation winding, a vice-output winding and an active snubber circuit are connected to a primary side of a flyback-based transformer. A main-output winding is connected to a secondary side of the transformer. A primary-side PWM controller and a secondary-side PWM controller are respectively connected to the primary side and the secondary side of the transformer. By a time-shared-energy-transfer method, the main-output winding and the vice-output winding are controlled to sequentially extract demand electricity from the transformer during a same switching cycle. Additionally, by a time-shared-energy transformation, the output voltage on the secondary side of the transformer is stabilized to be provided between a stable minimal voltage and a preset higher voltage for satisfying a heavy-loading status and a light-loading status.

Abstract: On the secondary side of a flyback switching power converter, a compensation diode and a voltage divider with an averaging circuit generate an output current-compensated reference voltage that is proportional to converter output current. The current-compensated reference voltage is added to a regulation feedback controller reference voltage, which in turn adjusts the negative feedback signal to the PWM regulation controller on the primary side in proportion to the converter output current draw. The net effect is to increase the converter output voltage set-point in proportion to the converter output current draw as compensation for a voltage drop in a cable connecting the converter to a powered device. More precisely-regulated voltage levels may be delivered to an input of the powered device as a result.

Abstract: A first rectified voltage obtained by rectifying an AC voltage is input to an input detection terminal of a control circuit. A first NMOS transistor configured as a depletion-type high-voltage element, and its drain is connected to the input detection terminal, and its gate is connected to its source. An AC voltage detection circuit detects the amplitude of the AC voltage based on a current that flows through the first NMOS transistor.

Abstract: A voltage converter controller and a voltage converter circuit, either of which includes a voltage-drop compensating circuit for compensating a voltage drop between an output voltage and a load. The voltage-drop compensating circuit includes a trans-conductance stage and a squarer. The trans-conductance stage outputs a compensating sink current to a voltage dividing terminal of the output voltage and outputs a compensating source current to a reference voltage terminal of an error amplifier. An input terminal of the squarer is coupled to an output terminal of the error amplifier. An output terminal of the squarer is coupled to an input terminal of the trans-conductance stage.

Abstract: Provided is regulation of a line current. The regulation of the line current includes comparing a reference voltage with a line sensing voltage to generate a feedback voltage, and controlling a switching operation of a power switch using the feedback voltage. The reference voltage may be a voltage having a constant level, a voltage which varies according to an output current, or a voltage which follows a sine wave to compensate a power factor. Provided is sensing of an output current. The sensing of the output current includes sensing the output current using a feedback voltage corresponding to a voltage between both terminals of an inductor connected to a power switch, a peak of current flowing through the power switch, and a switching cycle of the power switch.

Abstract: A switching power converting apparatus includes a voltage conversion module, a detecting unit, and a switching signal generating unit. The voltage conversion module converts an input voltage into an output voltage associated with a secondary side current, which flows through a secondary winding of a transformer and is generated based on a switching signal. The detecting unit generates a detecting signal based on the output voltage and a predetermined reference voltage. The switching signal generating unit generates the switching signal based on the detecting signal and an adjusting signal so that the secondary side current is gradually increased during a start period of the switching power converting apparatus.

Abstract: This relates to sampling a feedback signal representative of an output of a power converter. The sampling is performed using a buffer sampling circuit having three sample and hold stages coupled in series to sense and store the feedback signal. The first stage is coupled to sample and hold the feedback signal on a capacitor. If the output diode is conducting, the sampled signal is transferred to the second stage. If the output diode is conducting, the first stage will sample the feedback signal and the sampled signal will be transferred to be sampled and held by the second stage. When the output diode stops conducting, the sampled voltage held by the second stage is transferred to the third stage. The third stage stores the sampled voltage on a capacitor. As such, the controller may sample the feedback signal near the end of the output diode conduction time.

Abstract: A method for controlling an active-clamp flyback power converter is provided. The method includes comprises: generating a switching signal in response to a feedback signal for switching a low-side transistor and regulating an output of the active-clamp flyback power converter; generating an active-clamp signal after the switching signal is disabled; generating a hysteresis bias to adjust the feedback signal; and generating a pulse signal periodically to enable the switching signal. The low-side transistor is coupled to switch a transformer. The switching signal is coupled to drive the low-side transistor. The active-clamp signal is coupled to drive a high-side transistor. A pulse width of the active-clamp signal is determined by a first resistor. The high-side transistor is connected in series with a capacitor to develop an active-clamp circuit. A minimum frequency of the switching signal is determined by a second resistor during a heavy load condition.

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: 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: The power supply includes a transformer for generating a first output voltage by a first secondary winding, and a superimposing voltage by a second secondary winding, and a driver. Furthermore, the circuit includes first and second rectifying and smoothing circuits for respectively rectifying and smoothing the first output voltage and superimposing voltage, and an adder for adding the rectified and smoothed superimposing voltage on the rectified and smoothed first output voltage to output a second output voltage. The first and second output voltages are fed back respectively by DC coupling, the fed-back first and second output voltages are respectively adjusted by first and second feedback factors, and the adjusted feedback components are combined and amplified to be applied to the driver for PWM-control.

Abstract: Provided is a switching power supply device in a critical mode, including a load detection section that detects a load. When the detected load is lighter than a setting value, an upper limit of a switching frequency is lowered stepwise.

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: A power supply device includes, for example, a switching element, a rectifying circuit having a first rectifying element, and a control circuit which controls an output of the rectifying circuit. In particular, the power supply device includes a detection unit which detects a current flowing through the first rectifying element, and an output reduction unit which reduces the output of the rectifying circuit as an output of the switching power supply device. The output reduction unit changes a switching state of the switching element when the detection result of the detection unit exceeds a predetermined value.

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

Abstract: In one embodiment, a power switch driving circuit can include: (i) an upper switch having a first power terminal coupled to a voltage source, and a second power terminal coupled to a driving signal; (ii) a lower switch having a first power terminal coupled to the driving signal, and a second power terminal coupled to a first voltage level, where the first voltage level is higher than a first ground potential; (iii) an upper switch driving sub circuit configured to receive a control signal, and to drive the upper switch in response thereto; and (iii) a lower switch driving sub circuit configured to receive the control signal, and to drive the lower switch in response thereto, where the upper and lower switch driving sub circuits are coupled to a second ground potential.

Abstract: A method providing short-circuit protection and a flyback converter utilizing the same wire are disclosed. The a method, adopted by a flyback converter, includes a transformer, including generating a feedback voltage according to an output voltage output from a secondary winding of the transformer; controlling a primary current through a primary winding of the transformer based on the feedback voltage; determining a sense voltage according to the primary current; determining a short circuit based on the sense voltage; setting the primary current according to a short-circuit sense voltage limit when a short circuit occurs; and setting the primary current according to a normal sense voltage limit when a short circuit does not occur.

Abstract: A controller for a power converter includes a drive circuit coupled to generate a drive signal in response to an error signal representative of a load of the power converter. The drive circuit includes a pulse skipping circuit coupled to generate a blanking signal in response to the error signal. The pulse skipping circuit includes an enable circuit and a blanking circuit. The enable circuit is coupled to output an enable signal in response to the error signal. The blanking circuit is coupled to output the blanking signal in response to the enable signal and a ramp signal. The ramp signal is generated in response to the error signal. A duration of the blanking signal corresponds to a length of time for the ramp signal to reach a reference signal. The length of time is responsive to the error signal.

Abstract: System and method for regulating a power converter. The system includes a comparator configured to receive a first signal and a second signal and generate a comparison signal based on at least information associated with the first signal and the second signal. The first signal is associated with at least an output current of a power converter. Additionally, the system includes a pulse-width-modulation generator configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, and a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter. The modulation signal is associated with a modulation frequency corresponding to a modulation period.

Abstract: A switching power supply apparatus includes a PFM control circuit that outputs a clock signal Set such that a switching frequency of a switching element varies in accordance with a load state. The clock signal Set determines a turn-on timing of the switching element. A reference value of a current flowing through the switching element determines a turn-off timing of the switching element. A modulation signal is applied to the turn-off timing of the switching element to modulate one of a peak value of a drain current flowing through the switching element and an on-time of the switching element. Input control is performed separately on the clock signal Set and the modulation signal. Accordingly, even when the clock signal Set and the modulation signal contribute to each other to offset each other, modulation effects are not cancelled.

Abstract: A protection circuit of a DC-DC converter is disclosed. An input terminal of the DC-DC converter receives an input voltage and an output terminal of the DC-DC converter provides an output voltage. The DC-DC converter includes an output stage between the input terminal and the output terminal. The protection circuit includes a current sensor, a comparator, a determining circuit, and a protection control circuit. The current sensor provides a sensing signal. The comparator compares a default over-voltage with the sensing signal to provide an over-current control signal. The determining circuit provides a determining control signal. The protection control circuit determines whether to enable a short protection according to the over-current control signal and the determining control signal.

Abstract: The present invention relates to a switch control circuit that controls a switching operation of a power switch circuit that includes cascode-coupled first and second transistors. A switch control circuit includes a first zener diode coupled between a gate of the first transistor and a first end of a capacitor supplying a power voltage and a second zener diode coupled to a gate and a source of the first transistor, and a first resistor coupled between the first zener diode and the second zener diode.

Abstract: A power supply apparatus comprises: a transformer that includes primary/secondary windings that are electromagnetically connected to each other with polarities opposite to each other, an output switch that activates/inactivates an electric-current route that extends from an application terminal for an input voltage to a ground terminal via the primary winding a rectifying-smoothing portion that generates an output voltage from an induced voltage, a feedback voltage generation portion that monitors a switch voltage appearing at a connection node between the primary winding and the output switch and generates a feedback voltage in accordance with the output voltage, a reference voltage generation portion that generates a reference voltage, a comparator that compares the feedback voltage and the reference voltage with each other to generate a comparison signal, and a switching control portion that generates an output switch control signal by means of an on-time control method in accordance with the comparison si

Abstract: A controller for use in a power converter includes a comparator coupled to receive a signal representative of an output of the power converter. A counter is coupled to an output of the comparator to sample the output of the comparator a plurality of times within a period. A state machine is coupled to an output of the counter to control switching of the power converter according to one of a plurality of operating condition states in response to the output of the counter. The state machine is coupled to be updated at an end of the period.

Abstract: A switching power converter includes an inductor coupled to a terminal operably supplied with an input voltage. A semiconductor switch is coupled to the inductor and configured to enable and disable an input current passing through the inductor in accordance with a drive signal. A current sense circuit is coupled to the inductor or the semiconductor switch and is configured to generate a current sense signal representing the input current passing through the inductor or the semiconductor switch. A control circuit receives the current sense signal and is configured to: close the semiconductor switch regularly in accordance with a clock frequency, to integrate the current sense signal thus providing an integrated current sense signal to compare the integrated current sense signal with a threshold that is a function of the input voltage.

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: A controller for use in a power converter includes a drive circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from a power converter input to a power converter output. The controller also includes an input for receiving an enable signal including enable events responsive to the power converter output. The drive circuit is coupled to turn ON the power switch in response to the enable events and turn OFF the power switch in response to a power switch current reaching a current limit threshold. A current limit threshold generator is coupled to receive the drive signal from the enable events of the enable signal. The current limit threshold may be a ramp signal and the ramp signal along with the time between enable events may be used to modulate the drive signal.

Abstract: One embodiment includes a power supply system including a transformer comprising a primary, secondary, and auxiliary winding that are magnetically coupled. The system also includes a switch stage that generates a current through the primary winding in response to activation of a switch based on a control signal that is generated based on a feedback voltage associated with the auxiliary winding. The current can be induced in the secondary winding. The system also includes an output stage coupled to the secondary winding and that generates an output voltage based on the current induced in the secondary winding. The system further includes a feedback stage coupled to the auxiliary winding and comprising a discriminator configured to determine a zero-current condition associated with the current induced in the auxiliary winding based on monitoring a change in slope of the feedback voltage and to measure the feedback voltage during the zero-current condition.

Abstract: A control circuit of a flyback power converter includes a first reference signal generating circuit for generating a first reference signal; a reference signal adjusting circuit for generating an adjustment signal according to the first reference signal and a test signal corresponding to an output voltage signal of the flyback power converter, and to generate a second reference signal according to the adjustment signal and the first reference signal; an error detection circuit for generating an error signal according to the second reference signal and a feedback signal; and a control signal generating circuit for generating a control signal according to the error signal to control operations of a power switch to thereby adjust the test signal. The feedback signal corresponds to a current flowing through a primary side coil of the power converter or a sensing voltage of an inductive coil of the power converter.

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: System and method for regulating a power conversion system. An example system controller includes a signal processing component and a driving component. The signal processing component is configured to receive a feedback signal associated with an output signal of a power conversion system and generate a processed signal based on at least information associated with the feedback signal. The driving component is configured to generate a drive signal based on at least information associated with the processed signal and output the drive signal to a switch in order to affect a primary current flowing through a primary winding, the drive signal being associated with a demagnetization period corresponding to a demagnetization process of the power conversion system. The signal processing component is further configured to, sample and hold the feedback signal a plurality of times during the demagnetization period to generate a plurality of sampled and held signals.

Abstract: System and method for regulating a power conversion system. An example system controller for regulating a power conversion system includes a signal generator and a driving component. The signal generator is configured to receive a feedback signal associated with an output signal of a power conversion system and a current sensing signal associated with a primary current flowing through a primary winding of the power conversion system and generate a modulation signal based on at least information associated with the feedback signal and the current sensing signal. The driving component is configured to receive the modulation signal and output a drive signal to a switch based on at least information associated with the modulation signal.