Tool/software:
Hello. I am designing a board that must acquire the signals of some geophones and I want to use the ADS1285 analog-to-digital converter. In the datasheet I can not find the indication of the input impedance of the PGA pins. Can you provide me with this data?
Hi Giancarlo De Marchi,
You can infer the input impedance from the amplifier input current, for example the input impedance can be approximated as 1V / 45 nA = 22.2Mohm. I have copied with the relevant specs below from the datasheet (PGA enabled, or PGA bypassed i.e. buffer = on). There are also plots across input voltage in the datasheet that you can review.
-Bryan
