I'm currently developing a 1700W PFC with UCC28070.
It works but when I'm at 115VAC and 1700W output and I'm running a step load test from 100% to 50% (1700W to 850W), I have a small overshoot on my voltage, which I think might trigger the OVP. I can hear a short sound and I can see some odd ringing/triangular shape on my 100Hz ripple. The phenomenon is almost gone if I raise the voltage to e.g. 150VAC.
My feedback network is 3x680k to 15K39, which is equal to 400V output. (3V on Vsense). I have connected a 47nF CER CAP in parallel with the 15K39 in order to have some noise suppression. The CAP is places right next to the IC. (Tau = 96ms). I've also tried without cap, but it was the same.
The load step from 50% to 100% (850W to 1700W) is not a problem at all, so it's not OCP or Cycle-by-Cycle current limit.
Yellow: Output voltage ripple. Measured DC.
Red: Output current (from 4,25A to 2.12A).
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Kind regards
CWilson
