A flyback power converter converts an input power on a primary side into an output power on a secondary side. On the secondary side, the output power is monitored to provide a representative signal representing a characteristic of the output power. A count is kept unchanged when a clock ticks if the representative signal is within a first range defined in accordance with a target value, that the representative signal is going to be regulated at. The count is changed in response to the clock if the representative signal is within a second range different from the first range. In response to the count, a driving current is generated to control a coupler, which generates a compensation signal on the primary side that controls power transmitted from the primary side to the secondary side.