Feedback loop calculation for offline Flyback SMPS

Thread Starter


Joined Jul 22, 2012
The FSDMxxxx series of flyback controllers, and the FSCQxxxx series of QR Flyback controllers, have an effective feedback loop primary side pullup resistor of value 2.8k.
..Considering the FAN6300 QR Flyback controller, would you agree that its “equivalent” pullup resistor value is 5k?
The FAN6300 datasheet and App note (below) don’t say.

FSCQxxxx datasheet:

FSDMxxxx datasheet:

FAN6300 datasheet

FSCQxxxx series App Note:

FSDMxxxx series App Note:

FAN6300 App Note: