Abstract: A valley detecting circuit and method are provided for a voltage across a switching device, which detect a voltage across the switching device to produce a first voltage proportional to the voltage across the switching device, clamp the first voltage to produce a second voltage, level shift the second voltage to produce a third voltage, and compare the second voltage with the third voltage to determine a valley for the first voltage.

Abstract: A controller which has functions of remote control, multiple protection and PWM inside. The controller can shut down and latch the converter, when a failure happens (such as under voltage and over voltage of output, and over power protection). But, under-voltage and over-power protection will also happen when Vin is decreased by AC interruption or Vin source is removed. This invention is to provide a method to reset the latch protection by detecting Vin and Vo voltage.

Abstract: Disclosed are circuits and methods for use in a control circuit of a switching mode power supply for turning on a switching device in the switching mode power supply when the voltage across the switching device is at a minimum. A voltage detector is provided for detecting the voltage across the switching device to produce a detection voltage which is a function of the voltage across the switching device, and circuit arrangement is used to predict a valley timing for the voltage across the switching device by evaluating the time period that the detection voltage falls down from a first threshold to a second threshold.

Abstract: Disclosed are circuits and methods for use in a control circuit of a switching mode power supply for turning on a switching device in the switching mode power supply when the voltage across the switching device is at a minimum. A voltage detector is provided for detecting the voltage across the switching device to produce a detection voltage which is a function of the voltage across the switching device, and circuit arrangement is used to predict a valley timing for the voltage across the switching device by evaluating the time period that the detection voltage falls down from a first threshold to a second threshold.

Abstract: An apparatus and method for a flyback power converter reduce the standby output voltage of the flyback power converter by switching the reference voltage provided by a shunt regulator of the flyback power converter or the ratio of voltage divider resistors of the shunt regulator, to reduce the standby power consumption by an output feedback circuit of the flyback power converter, the shunt regulator, and the voltage divider resistors, and thereby the power loss of the flyback power converter in standby mode.

Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.

Abstract: A charger has two pins for connecting with a battery therebetween, and an apparatus and method are proposed to determine to wake up or turn off the charger according to a voltage or a current detected from the two pins, to reduce the standby power consumption of the charger.

Abstract: A voltage detector circuitry extracts a signal on primary side of a transformer in a flyback converter, which is proportional to the output voltage of the converter without voltage drop on the rectifier diode and leakage inductance effect on the transformer, and good output regulation is achieved without opto-coupler. To accurately detect the output voltage on the primary side, the knee point of the voltage on an auxiliary winding of the transformer is detected. A current limit proportional to the input voltage of the converter is produced from the voltage on an auxiliary winding for stabilizing the output current in constant current mode.

Abstract: A power converter has a transformer including a primary winding connected between a power input and a power switch, the power switch is switched to deliver power from the power input to a power output, an auxiliary winding provides an induced voltage in such a manner that when the power switch is at a first switch state, the induced voltage reflects an input information of the power converter, and when the power switch is at a second switch state, the induced voltage reflects an output information of the power converter. Two detection signals are generated from the input and output information, respectively, to implement multiple functions and protections.

Abstract: A controller which has functions of remote control, multiple protection and PWM inside. The controller can shut down and latch the converter, when a failure happens (such as under voltage and over voltage of output, and over power protection). But, under-voltage and over-power protection will also happen when Vin is decreased by AC interruption or Vin source is removed. This invention is to provide a method to reset the latch protection by detecting Vin and Vo voltage.

Abstract: A frequency jittering circuit modulates a hysteretic band of an oscillator such that the clock generated by the oscillator has a jitter frequency, and thus a switching mode power supply operative on the clock will have a jittering switching frequency.

Abstract: A flyback power converter includes a power switch connected to a primary side of a transformer, and a sensing signal is provided for a control circuit to switch the power switch so as for the transformer to convert an input voltage into an output voltage. The sensing signal is a function of the input voltage, and the control circuit extracts a variation of the sensing signal during a preset time period. The variation of the sensing signal is used to prevent the output ripple and the green mode entry point of the flyback power converter from varying with the input voltage.

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 power converter uses a PWM controller to provide a driver output to modulate the duty of the power converter. A protection apparatus and method compare a current sense input of the PWM controller with a reference voltage to assert a signal representing failure, count the number of cycles where the signal representing failure is asserted, and reset an enable signal to inhibit the driver output if the signal representing failure is asserted in several cycles.

Abstract: A voltage detector circuitry extracts a signal on primary side of a transformer in a flyback converter, which is proportional to the output voltage of the converter without voltage drop on the rectifier diode and leakage inductance effect on the transformer, and good output regulation is achieved without opto-coupler. To accurately detect the output voltage on the primary side, the knee point of the voltage on an auxiliary winding of the transformer is detected. A current limit proportional to the input voltage of the converter is produced from the voltage on an auxiliary winding for stabilizing the output current in constant current mode.

Abstract: A frequency jittering circuit modulates a hysteretic band of an oscillator such that the clock generated by the oscillator has a jitter frequency, and thus a switching mode power supply operative on the clock will have a jittering switching frequency.

Abstract: A power converter has a transformer including a primary winding connected between a power input and a power switch, the power switch is switched to deliver power from the power input to a power output, an auxiliary winding provides an induced voltage in such a manner that when the power switch is at a first switch state, the induced voltage reflects an input information of the power converter, and when the power switch is at a second switch state, the induced voltage reflects an output information of the power converter. Two detection signals are generated from the input and output information, respectively, to implement multiple functions and protections.

Abstract: Disclosed are circuits and methods for use in a control circuit of a switching mode power supply for turning on a switching device in the switching mode power supply when the voltage across the switching device is at a minimum. A voltage detector is provided for detecting the voltage across the switching device to produce a detection voltage which is a function of the voltage across the switching device, and circuit arrangement is used to predict a valley timing for the voltage across the switching device by evaluating the time period that the detection voltage falls down from a first threshold to a second threshold.

Abstract: A valley detecting circuit and method are provided for a voltage drop across a switching device, which detect a voltage drop across the switching device to produce a first voltage proportional to the voltage drop across the switching device, clamp the first voltage to produce a second voltage, level shift the second voltage to produce a third voltage, and compare the second voltage with the third voltage to determine a valley for the first voltage.