摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.