Hi,
Are you sure pls, that your Ev.-Board is problem less to control if you will drive it from normal 5V supplyed logical gates?
Is it not a missed GND wire or some similar in system?
K.
Added after 21 minutes:
Sorry, what is exactly your input pls?
Signals from the 5V ADC logic or you wish to drive the ADC with its outputs from 3V external logic?
Because LVC244A accept 5V to translate on hes outputs for a level between 1.6..to..3.3V, but not in revers direction(not from 5V to lower levels)...
On the data sheet are notes 2/3; current to clamp for max 50mA_ is it not missed in your case?