Thanks for the link to teh schematic, there is another question
One question about the ADS8638 EVM please, do we need to power the
> HVDD and HVSS pins from somewhere? (i.e. an external PSU)
>
> It's not completely clear from the documentation.
>
> But, so far as I can see, the HVDD and HVSS pins of the chip will only be powered if you connect an external PSU either to J9 or J14 on the MMB0 base board.