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Part Number: ADS7953
I have an ADS7953 in my design, and I had a failure during EMC testing in the EMI chamber during what appears to be BCI at 1MHz. The chip fails in such that all of the channels work for say 50% of the range (almost like there is an offset). So it seems the reference voltage is being messed up? What is causing this?
Some things to note: the REF5025 is putting out a solid 2.5V, the layout is done as is shown in the data sheet, I have 4 unused channels that have the RC filter network on them, however they are floating.
If I replace the chip post failure, everything is fine, so it does seem that something is getting messed up in the chip.
What can I do to improve the robustness of my design to survive BCI?
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In reply to Evan Sawyer:
I have a 10uF, 6.3V X7R ceramic and a 22uF 10V X7R ceramic to ground. I could not check the 2.5V while it was in the chamber, however post test the 2.5V is solid. However the entire system is permanently "offset" on all of its values. It appears to be off by about 50%. And when I replace the ADS7953, everything is back to normal.
Also note that +Vbd = 5V.
Here is the schematic:
Here is the layout:
In reply to Joshua Schofield:
Copy and paste into this webform appeared to not work, so I tried using the attach button. Let me know if they come through.
The failure is permanent, as in only fixed with a part replacement. So when I replace the part, everything comes up fine. But I am worried about the susceptibility that the part appears to have.
Do you have any advice? We go back into the chamber in 2 weeks, so the only thing I can think of is grounding the floating pins, because if they were not grounded, they could be susceptible to bulk current injection (acting like antennas)?
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