Abstract: A control circuit and a method for controlling a power converter are provided. The method for controlling the power converter includes the following steps. A detection signal is received from the secondary side of the power transformer and a first switching signal is generated in accordance with the detection signal. A second switching signal is generated in accordance with the first switching signal. A voltage signal is generated in accordance with the second switching signal. A comparison signal is generated in accordance with the first switching signal and the second switching signal. The voltage signal and the comparison signal are compared for outputting a comparison result. A gate signal is generated in accordance with the detection signal and the comparison result to control on and off states of a synchronization switch.

Abstract: A controller for a power converter includes a clamping circuit, a switching circuit and a pulse generator. The clamping circuit is coupled to an input terminal of the controller for detecting a detection signal from a transformer. The switching circuit generates a switching signal to switch the transformer in response to the detection signal for regulating the power converter. A maximum level of the detection signal is clamped to be under a level of a threshold voltage during an off-period of the switching signal. Since the maximum level of the detection signal is clamped and the oscillating energy of the reflected signal is discharged, the speed of detecting the detection signal is increased. Therefore, the regulation of the primary-side controlled power converter can be improved accordingly.

Abstract: A trim circuit for a power supply controller includes: a control circuit; at least a capacitance type programmable circuit connection; and a switching circuit, under control of the control circuit, the switching circuit selectively coupling the capacitance type programmable circuit connection to anyone of an operation voltage and a programming voltage, for determining a programming state of the capacitance type programmable circuit connection.

Abstract: A control circuit with protection circuit for power supply according to the present invention comprises a peak-detection circuit and a protection circuit. The peak-detection circuit detects an AC input voltage and generates a peak-detection signal. The protection circuit comprises an over-voltage protection circuit. The over-voltage protection circuit generates an over-voltage protection signal in response to the peak-detection signal. The protection circuit generates a reset signal to reduce the output of the power supply in response to the over-voltage protection signal. The present invention can protect the power supply in response to the AC input voltage effectively through the peak-detection circuit.

Abstract: A start-up circuit with low standby power loss for power converters according to present invention comprises a first diode and a second diode coupled to an input voltage of the power converter. A start-up resistor is coupled to the join of the first diode and the second diode. A high-voltage switch is coupled to the start-up resistor to generate a power source. A control circuit generates a switching signal for switching a transformer. A detection circuit generates a disable signal in response to the input voltage to disable the switching signal. A winding of the transformer is coupled to the power source to generate the power for the power source. The high-voltage switch is turned off to cut off the start-up resistor for saving the power loss once the voltage of the power source is higher than a threshold.

Abstract: A synchronous rectifier for a switching power converter is provided and includes a power transistor, a diode, and a control circuit. The power transistor and the diode are coupled to a transformer and an output of the power converter for the rectification. The control circuit generates a drive signal to switch on the power transistor once the diode is forward biased. The control circuit includes a phase-lock circuit. The phase-lock circuit generates an off signal to switch off the power transistor in response to a pulse width of the drive signal. The pulse width of the drive signal is shorter than a turned-on period of the diode. The phase-lock circuit further reduces the pulse width of the drive signal in response to a feedback signal. The feedback signal is correlated to an output load of the power converter.

Abstract: A control circuit and a method for controlling a power converter are provided. The method for controlling the power converter includes the following steps. A detection signal is received from the secondary side of the power transformer and a first switching signal is generated in accordance with the detection signal. A second switching signal is generated in accordance with the first switching signal. A voltage signal is generated in accordance with the second switching signal. A comparison signal is generated in accordance with the first switching signal and the second switching signal. The voltage signal and the comparison signal are compared for outputting a comparison result. A gate signal is generated in accordance with the detection signal and the comparison result to control on and off states of a synchronization switch.

Abstract: A control circuit of a power converter for light-load power saving according to the present invention comprises a first feedback circuit coupled to an output voltage of the power converter to receive a first feedback signal. A second feedback circuit is coupled to the output voltage to receive a second feedback signal. A control circuit generates a switching signal for switching a transformer of the power converter and regulating the output voltage of the power converter in response to the first feedback signal and the second feedback signal. The switching signal is generated in accordance with the first feedback signal when an output load is high. The switching signal is generated in accordance with the second feedback signal during a light-load condition.

Abstract: An adaptive synchronous rectification control circuit and a control method are developed. The control circuit comprises an adaptive circuit that generates a reference signal in response to a detection signal of a power converter. A clamped circuit clamps the reference signal at a threshold voltage if the reference signal equals or is greater than the threshold voltage. A switching circuit generates a control signal to control a synchronous switch of the power converter in response to the detection signal and the reference signal. The control method generates the reference signal in response to the detection signal. The reference signal is clamped at the threshold voltage if the reference signal equals or is greater than the threshold voltage. The method further generates the control signal to control the synchronous switch of the power converter in response to the detection signal and the reference signal.

Abstract: A control circuit with protection circuit for power supply according to the present invention comprises a peak-detection circuit and a protection circuit. The peak-detection circuit detects an AC input voltage and generates a peak-detection signal. The protection circuit generates a reset signal to reduce the output of the power supply in response to the peak-detection signal. The present invention can protect the power supply in response to the AC input voltage effectively through the peak-detection circuit.

Abstract: A control circuit of an interleaved PFC power converter according to the present invention comprises a master switching control circuit, a slave switching control circuit, and a slave reference signal generator. The master switching control circuit generates a control signal and a first switching signal in response to an input voltage and a feedback signal. The first switching signal is utilized to control a first switch of the PFC power converter. The slave reference signal generator generates a slave control signal in response to a load condition of the PFC power converter and the control signal. The slave switching control circuit generates a second switching signal in response to the slave control signal. The slave control signal is utilized to control a second switch of the PFC power converter. The slave reference signal generator adjusts the control signal in response to the load condition for generating the slave control signal correspondingly.

Abstract: A trim circuit for a power supply controller includes: a control circuit; at least a capacitance type programmable circuit connection; and a switching circuit, under control of the control circuit, the switching circuit selectively coupling the capacitance type programmable circuit connection to anyone of an operation voltage and a programming voltage, for determining a programming state of the capacitance type programmable circuit connection.

Abstract: A method and an apparatus of operating a primary-side-regulation power converter at both continuous current mode and discontinuous current mode are provided. The apparatus includes a switching circuit, a signal generator, a correlation circuit, and a feedback modulator. The signal generator generates a half signal and a second sampling pulse in response to a switching signal. The correlation circuit receives the half signal, the second sampling pulse and a switching-current signal for generating a modulating current. The feedback modulator modulates a feedback signal in response to the modulating current, a detection signal and the switching signal. The detection signal obtained from a transformer is correlated to an output voltage of the primary-side-regulation power converter. An on-period of the half signal is half of an on-period of the switching signal. The switching-current signal is sampled at a falling-edge of the half signal.

Abstract: A control circuit of an interleaved PFC power converter according to the present invention comprises a master switching control circuit, a slave switching control circuit, and a slave reference signal generator. The master switching control circuit generates a control signal and a first switching signal in response to an input voltage and a feedback signal. The first switching signal is utilized to control a first switch of the PFC power converter. The slave reference signal generator generates a slave control signal in response to a load condition of the PFC power converter and the control signal. The slave switching control circuit generates a second switching signal in response to the slave control signal. The slave control signal is utilized to control a second switch of the PFC power converter. The slave reference signal generator adjusts the control signal in response to the load condition for generating the slave control signal correspondingly.

Abstract: A control circuit with protection circuit for power supply according to the present invention comprises a peak-detection circuit and a protection circuit. The peak-detection circuit detects an AC input voltage and generates a peak-detection signal. The protection circuit comprises an over-voltage protection circuit. The over-voltage protection circuit generates an over-voltage protection signal in response to the peak-detection signal. The protection circuit generates a reset signal to reduce the output of the power supply in response to the over-voltage protection signal. The present invention can protect the power supply in response to the AC input voltage effectively through the peak-detection circuit.

Abstract: An adaptive synchronous rectification control circuit and a control method are developed. The control circuit comprises an adaptive circuit that generates a reference signal in response to a detection signal of a power converter. A clamped circuit clamps the reference signal at a threshold voltage if the reference signal equals or is greater than the threshold voltage. A switching circuit generates a control signal to control a synchronous switch of the power converter in response to the detection signal and the reference signal. The control method generates the reference signal in response to the detection signal. The reference signal is clamped at the threshold voltage if the reference signal equals or is greater than the threshold voltage. The method further generates the control signal to control the synchronous switch of the power converter in response to the detection signal and the reference signal.

Abstract: A start-up circuit with low standby power loss for power converters according to present invention comprises a first diode and a second diode coupled to an input voltage of the power converter. A start-up resistor is coupled to the join of the first diode and the second diode. A high-voltage switch is coupled to the start-up resistor to generate a power source. A control circuit generates a switching signal for switching a transformer. A detection circuit generates a disable signal in response to the input voltage to disable the switching signal. A winding of the transformer is coupled to the power source to generate the power for the power source. The high-voltage switch is turned off to cut off the start-up resistor for saving the power loss once the voltage of the power source is higher than a threshold.

Abstract: A method and an apparatus of operating a primary-side-regulation power converter at both continuous current mode and discontinuous current mode are provided. The apparatus includes a switching circuit, a signal generator, a correlation circuit, and a feedback modulator. The signal generator generates a half signal and a second sampling pulse in response to a switching signal. The correlation circuit receives the half signal, the second sampling pulse and a switching-current signal for generating a modulating current. The feedback modulator modulates a feedback signal in response to the modulating current, a detection signal and the switching signal. The detection signal obtained from a transformer is correlated to an output voltage of the primary-side-regulation power converter. An on-period of the half signal is half of an on-period of the switching signal. The switching-current signal is sampled at a falling-edge of the half signal.

Abstract: A controller for a power converter includes a clamping circuit, a switching circuit and a pulse generator. The clamping circuit is coupled to an input terminal of the controller for detecting a detection signal from a transformer. The switching circuit generates a switching signal to switch the transformer in response to the detection signal for regulating the power converter. A maximum level of the detection signal is clamped to be under a level of a threshold voltage during an off-period of the switching signal. Since the maximum level of the detection signal is clamped and the oscillating energy of the reflected signal is discharged, the speed of detecting the detection signal is increased. Therefore, the regulation of the primary-side controlled power converter can be improved accordingly.

Abstract: A low-pass filter of the present invention comprises a plurality of filter units and a regulation unit. The filter units are coupled in series with each other and receive an input signal to filter the input signal for generating an output signal. The regulation unit is coupled to the filter units to regulate voltage levels of the filter units. The low-pass filter of the present invention can be integrated within the integrated circuit and reduce the prime cost.