Power Integrations Flyback....Feedback Loop calculation

[Faringdon]

Hi,

I did the attached TOPswitch-HX Flyback design in PI Expert.
I then used the equations given by Power Integrations in AN-57 to calculate the crossover frequency, gain and phase margins.
However, the equations given in AN-57 give nonsense Bode Plots (as attached in Excel)

AN-57:
https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjfwabJmJGAAxUhV0EAHWp1BLkQFnoECBsQAQ&url=https%3A%2F%2Fwww.power.co…

Do you know how to calculate the feedback loop for this TOPswitch-HX design?
It is Offline Universal flyback 24vout and 800mA out.

As you know, Only Power Integrations know what controller gains they have put in their chips, so we are dependent on their equations.