A
flyback converter (20) uses primary side sensing to sense the output
voltage for regulating feedback. The
flyback converter comprises a
transformer with a primary winding (L1) and a secondary winding (L2), a first
transistor (M1) coupled to the primary winding for conducting a current through the primary winding when the first
transistor is on a second
transistor (M2) for conducting a current through the secondary winding when the second transistor is on a
regulator (14) coupled to the first transistor for controlling a
duty cycle of the first transistor to regulate an output
voltage of the converter, the
regulator being configured to control the first transistor to have a minimum
duty cycle, an output
capacitor (C1) coupled to an output terminal of the converter, a
synchronous rectifier controller (24) coupled to the second transistor for controlling the second transistor to be on or off, a
comparator (42) having one input coupled to receive a
voltage corresponding to the output voltage of the converter and having another input connected to a reference voltage representing a
threshold voltage exceeding a regulated voltage of the converter, wherein triggering of the
comparator signifies an over-voltage condition, an output of the
comparator being coupled so as to control the
synchronous rectifier controller to turn the second transistor on for an interval to conduct a
reverse current through the secondary winding, upon an over-voltage condition being detected, to reduce the output voltage of the converter to mitigate the over-voltage condition, and a
diode (D1) coupled to the primary winding to conduct a current through the primary winding after the interval without turning on the first transistor, such that power is transferred from a
secondary side of the
transformer to the power source while mitigating the over-voltage condition.