In the EVM you use two banks of resistor before and after the latches. Does the
board work with values between 33 and 47 ohm for RN1 and RN3?
The board will be functional with all values of resistors up to the 470ohms.
The higher resistance limits the current / voltage transient, and its timing.
The 2 devices..the AD6644 and the AD6645 were characterized with different
values of resistors to find optimum values for dynamic performance (SNR /
SFDR). The T/H on the front end can be very sensitive to transients and their
timing in relation to the sampling instant, and this is different for the 2
devices (AD6645 has faster front end).