INA2180-Q1: accuracy impaction by Zener diode&R

Hello Ryan,

We do not recommend resistors above 10Ω.  We have a calculation for Gain error on page 23 of datasheet.  Equation number (4) with example calculations in on table2 below that equation.

Javier,

So what's your suggestion for this scenario for "load dump" test?

Or do you have another part to recommend which can survive from 36V strike at IN+/IN-?

OPA2192-Q1 can meet requirement but is too expensive. They want something cheaper.

Thanks a lot

Hi Ryan,

if I may add something: Additionally to that the filtering resistors should not exceed 10R for gain error reasons, the problem is that any imbalance introduced by the two protection schemes will ruin the awesome common mode rejection of INA2180. Usually, there's only the very small shunt between the inputs allowing both inputs to see a very similar or even identical source impedance situation. This allows highest common mode rejection. But if you add protection diodes with uneven junction capacitances being isolated by current limiting resistors, both inputs see no longer identical source impedances and the common mode rejection is ruined. Of course, you can do some fine trimming with adjustable capacitances or hand selection of TVS for identical performance but this is hardly something for mass production. Also, the fine tuning of input capacitances will depend on the actual mounting and cabling conditions.

Take care, load dump protection is difficult because of the enormeous energy of the load dump pulse. This cannot be done with 10R resistors. Because of that many cars provide a central load dump pulse protection. So, are you sure that your circuit has to withstand the full load dump pulse at all?

Kai

Kai,

So do you have another part to recommend which can survive from 36V strike at IN+/IN- other than OPA2192 which is too expensive?