AD7770 maximum range


I'm using the Eval Board of AD7770.

The maximum amplitude I can measure between AIx+ and AIx- is +/- 1.65V (dual supply operation)

According to the AD7770 datasheet, he noted that the maximum amplitude is +/- 2.5V (according to table 11 of the datasheet).

A7770 datasheet extract :

How do I configure my eval board to get such an amplitude?

Thank you in advance and best regards,

Maxime Charrière