Hello,
I'm working with the power factor correction controller Ucc28180 for my current PFC design. I'm current testing at the worse case load condition, which is 85 V and highest load. I'm seeing something very unusual, wherein the switching frequency varies almost 20KHz from the set frequency (120KHz) based on whether its at the highest or the lowest duty cycle. I see some variation in your TI evaluation board as well but this is hardly 4KHz. Could you help me understand why am I seeing such huge variation?, what could be the possible cause? Also, I notice that in your eval board you have some space for connecting a capacitor in parallel with the frequency setting resistor, but you haven't connected anything there, however I have used a small capactior in that place, just for regulation, due you think that could play a role?
Regards,
Shruti W
