I have the technical questions on EFT/B immunity (IEC 61000-4-4) fail at 4kV through the input power supply of 24Vdc common line.
We isolated the failure is caused by the ADA4091-2 because if i change to the existing part of op amp it will pass the 4kV EFT test in the exactly same design setup.
Could you help to advises any solution to solve this EFT/B immunity for industrial control IEC61000-4-4?
ADA4091-2/4 has two different ESD circuits for enhanced protection as shown on the DS rev. H page 15 figure 48. However, the test methods and results for these tests are not publised in the datasheet. But given that sophisticated input protection for ampliifier, I'm not sure why would it cause the failure. Maybe, some of other components might also contribute to the event of failure. I'll need to verify.
You can refer to INPUT OVERVOLTAGE PROTETION section of the datasheet for the details of the input ESD circuits which I think might help you. I'll try to get some data on the ESD test results for our reference.