In ADCs, what are Pseudo-Bipolar Inputs

[brazingo]

hi,
i've been looking for bipolar ADC. I came across one which says it
is a unipolar differential but supports pseudo-bipolar. what does
pseudo-bipolar mean ? I tried googling and found only 'pseudo
-bipolar' products but no description on what that means.

 

[John Larkin]

hi,
i've been looking for bipolar ADC. I came across one which says it
is a unipolar differential but supports pseudo-bipolar. what does
pseudo-bipolar mean ? I tried googling and found only 'pseudo
-bipolar' products but no description on what that means.

It means both inputs must be positive with respect to ground, but one
can be measured "bipolar" with respect to the other.

So if you hold the negative input pin at +2.5 and move the pos pin
around, you can appear to measure -2.5 to +2.5 as the + input actually
goes from 0 to 5. So then you can play some tricks with external
level-shifting resistors to measure true bipolar signals.