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Reducing the drive strength from maximum to minimum involves a considerable interference reduction as well, I think there's reason for hope.
But, when redesigning the board, why didn't you change to Cyclone III or IV? It can be expected to end the ground bounce/SSN related PLL unlock problems.
Regards,
Frank
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In general I think the layout and power supplies are ok now (filters on PLL inputs, ground and power planes, ultra short tracking etc etc).
Yes, I agree that this feels more like an "analog" fix rather than a logical fix, however if it proves reliable then I will put aside my residual concerns :)
As to Cyclone III, (I haven't checked this) I think our only options at this size chip would be BGA. We did a BGA design once but were frightened by the whole layout and pcb building process. Plus you can't scope the pins easily.
I know we will have no choice in this one day :(
Pete
Honored Contributor
