I have a design 193V output voltage and 700mA current, but when the current drawn from output, the auxilary winding voltage fall down, and IC shut down PWM gate signal as you can see in the attachment and the output voltage go to zero. And I could not understand, why auxilary voltage is like sawtooth wave, I think the IC try to open PWM but can not start. Can any body help me about that issue?
The FAN6754 will shut down when the supply drops below 9 volts and not restart until that voltage rises above 16.5 volts. Given that it can work at a peak supply voltage that is closer to 30 volts, it seems that more turns on your auxiliary winding might be the route to go.