AD7195: Input impedance in buffered mode

Q

I am using the AD7195 in buffered mode.
I need to know the input impedance between the AIN+ AIN- inputs.
In the data sheet is only written that is high. But which is (more or less) its
value ?

A

With the buffer of the AD7195 (http://www.analog.com/AD7195) enabled, the input
current is 2 nA maximum for a gain of 1 and 4.5 nA maximum for higher gains.
Kindly find these values in table 1 on page 4 of the specification. For your
reference I’ve copied the relevant section below.

So, if the input voltage is 5V, then the impedance is:

5V/4.5nA = 1Gohm.

Kindly mark, that this is a worst case scenario of the AD7195.