Hello Anna,
I have replaced the AD8429 with the AD8421. It works fine. I dont get problems with the saturation.
But their is one point, I need more informations.
The maximum rating of the input voltage is ca. +-35V with UCC=+-5V.
I have BAV199 diodes at the input, which limit the signal (shown in the picture)
,
I want to know, what is happening with power dissipation about the Rg resistance.
Assume, the input voltage is to high and the diodes limit it, to u_diff.
For example u_diff = u_p - u_n = 5Vp - -5Vp = 10Vp = 7.07V and Rg = 10 ohm.
I have found in the datasheet, that the voltage about Rg is the 2*u_diff.
I get P = U^2 / Rg = (2*7.07V) ^ 2 / 10 ohm = 20 watt.
What happen by this condition?
1. If the INA destroyed ?
2. Limit the INA the current through Rg?
3. What can be the maximum current through Rg?
4. Did I need an additional protection at the input, like in the picture?
Thank you very much for yout help.
Best regards
Dirk