Hi all,
I am working on a 1000W pfc based on ucc28070. The design seems to work fine except for one peculiar thing.
At high load conditions (>800W) the output voltage sags. It seems like a power limiting mechanism. Looking at the CTX signals, the controller seems to scip cycles. This happens also at high line conditions ( Vin 240V) where the measured current is far from peak limit treshold. When I reduce the burden resistors for the current transformers by 20% the units works fine up to 1000W, also at 85V Vin.
Anybody an idea what is happening?
