On our second run of 25 boards (first 25 fine), 20% will blow PFC Fet. I believe this is caused by the PFC chock saturating. Most boards will operate fine to full power; but some will not. Moving the PFC chock from a good board to a bad one does not change correct the current tic? Can you help me understand what the cause is of this intermittent tic is? Our board’s primary circuit and board layout is nearly the same as your RD189 evaluation board. One discrepancy I found was that the two diodes across PFC Sense resistor are DL4007 with no I sq t or high surge rating.
I have attached some scope print outs to demonstrate this problem.