PCN 11_0006 says AD9945 has got a new SPI register. As mentioned in the Rev B
datasheet, the value 0x838 has to be written into the new register at startup.
How can I handle mixed stock of parts pre and post PCN 11_0006.
There is not two revs of the part, only two revs of the datasheet. The new
register was always there, it just was not documented. If you have mixed stock
from last couple of years for the purpose of building new boards then you can
just treat all parts in the same way (using the new register write).
There is no advantage is going back and setting new register writes on old
built boards this is extra cost with no benefit.