Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: A switched-mode power supply with near valley switching includes a quasi-resonant converter. The converter includes a switch element that is turned on not only at the valley, but also in a window range of ?tNVW close to the valley, where the voltage across the switch element is at its minimum. This advantageously reduces switching loss and maintains a balance between efficiency and frequency variation.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: A switched-mode power supply with near valley switching includes a quasi-resonant converter. The converter includes a switch element that is turned on not only at the valley, but also in a window range of ?tNVW close to the valley, where the voltage across the switch element is at its minimum. This advantageously reduces switching loss and maintains a balance between efficiency and frequency variation.

Abstract: A switched-mode power supply with near valley switching includes a quasi-resonant converter. The converter includes a switch element that is turned on not only at the valley, but also in a window range of ?tNVW close to the valley, where the voltage across the switch element is at its minimum. This advantageously reduces switching loss and maintains a balance between efficiency and frequency variation.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: A method for communicating with a power converter comprises initiating a communication sequence by sensing a first distortion of a sensed waveform during a discharge period of a first power transfer cycle of the power converter. The sensed waveform is proportional to a secondary current of the power converter. At a primary side of the power converter, a data bit is received from a secondary side of the power converter, by sensing a second distortion to represent one state of the data bit and sending an absence of the second distortion to represent another state of the data bit. The secondary distortion is applied to the secondary current during the discharge period of a subsequent power transfer cycle.

Abstract: A method for communicating with a power converter comprises initiating a communication sequence by sensing a first distortion of a sensed waveform during a discharge period of a first power transfer cycle of the power converter. The sensed waveform is proportional to a secondary current of the power converter. At a primary side of the power converter, a data bit is received from a secondary side of the power converter, by sensing a second distortion to represent one state of the data bit and sending an absence of the second distortion to represent another state of the data bit. The secondary distortion is applied to the secondary current during the discharge period of a subsequent power transfer cycle.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a circuit configured configuring the PWM circuit to form a first signal having a value formed to be representative of a peak value of a primary current through the power switch and having a duration that is representative of a time interval that a secondary current is flowing through a secondary winding wherein the peak value is the peak value during an on-time of the power switch, and configured to form a current having a value that is representative of an average value of the secondary current.

Abstract: A method for communicating with a power converter comprises initiating a communication sequence by sensing a first distortion of a sensed waveform during a discharge period of a first power transfer cycle of the power converter. The sensed waveform is proportional to a secondary current of the power converter. At a primary side of the power converter, a data bit is received from a secondary side of the power converter, by sensing a second distortion to represent one state of the data bit and sending an absence of the second distortion to represent another state of the data bit. The secondary distortion is applied to the secondary current during the discharge period of a subsequent power transfer cycle.

Abstract: A method for communicating with a power converter comprises initiating a communication sequence by sensing a first distortion of a sensed waveform during a discharge period of a first power transfer cycle of the power converter. The sensed waveform is proportional to a secondary current of the power converter. At a primary side of the power converter, a data bit is received from a secondary side of the power converter, by sensing a second distortion to represent one state of the data bit and sending an absence of the second distortion to represent another state of the data bit. The secondary distortion is applied to the secondary current during the discharge period of a subsequent power transfer cycle.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a circuit configured configuring the PWM circuit to form a first signal having a value formed to be representative of a peak value of a primary current through the power switch and having a duration that is representative of a time interval that a secondary current is flowing through a secondary winding wherein the peak value is the peak value during an on-time of the power switch, and configured to form a current having a value that is representative of an average value of the secondary current.

Abstract: In one embodiment, a power supply controller, or alternately a semiconductor device having a power supply controller, may have a first circuit configured to form a sense signal that is representative of a signal from an auxiliary winding of a transformer. A feedback circuit may be configured to allow the sense signal to increase in response to a turn-off of the power switch, to subsequently detect a second increase of the sense signal prior to subsequently turning on the power switch, and to form a feedback signal as a value of the sense signal responsively to the second increase of the sense signal.

Abstract: A switched-mode power supply with near valley switching includes a quasi-resonant converter. The converter includes a switch element that is turned on not only at the valley, but also in a window range of ?tNVW close to the valley, where the voltage across the switch element is at its minimum. This advantageously reduces switching loss and maintains a balance between efficiency and frequency variation.

Abstract: A sampling circuit of the power converter according to the present invention comprises an amplifier circuit receiving a reflected voltage for generating a first signal. A first switch and a first capacitor are utilized to generate a second signal in response to the reflected voltage. A sample-signal circuit generates a sample signal in response to a falling edge of a switching signal. The switching signal is generated in accordance with a feedback signal for regulating an output of the power converter. The feedback signal is generated in accordance with the second signal. The sample signal is utilized to control the first switch for sampling the reflected voltage. The sample signal is disabled once the first signal is lower than the second signal. The sampling circuit precisely samples the reflected voltage of the transformer of the power converter for regulating the output of the power converter.

Abstract: A sampling circuit of the power converter according to the present invention comprises an amplifier circuit receiving a reflected voltage for generating a first signal. A first switch and a first capacitor are utilized to generate a second signal in response to the reflected voltage. A sample-signal circuit generates a sample signal in response to the disable of a switching signal. The switching signal is generated in accordance with a feedback signal for regulating an output of the power converter. The feedback signal is generated in accordance with the second signal. The sample signal is utilized to control the first switch for sampling the reflected voltage. The sample signal is disabled once the first signal is lower than the second signal. The sampling circuit precisely samples the reflected voltage of the transformer of the power converter for regulating the output of the power converter.

Abstract: A method for controlling a power converter is provided. The method includes the following steps. A switching signal coupled to switch a transformer for regulating the output of the power converter is generated in accordance with a feedback signal and a ramp signal. The ramp signal is generated in accordance with a switching current signal and a slope compensation signal. The slope compensation signal is generated in response to an input voltage signal. The input voltage signal is generated in response to the level of the input voltage of the power converter. The feedback signal is generated in accordance with the output of the power converter, and the switching current signal is correlated with a switching current of the transformer.

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.