Hi There, I am an old member of the CE course I have an question about ESD protection, I think this is a very interesting topic and should maybe be included in CE
I recently designed a circuit for a product which is now being produced.
However, during EMI and ESD tests it failed the ESD test.
Big problem of course since I had not anticipated that. Now I am looking for what I did wrong so I can potentially fix it.
The product consists of 2 load cells both with an instrumental amplifier behind it. (AD8226)
The AD8226 is ESD protected to 1.5kV but apparently this is not sufficient and should be 8kV…
If the load-cells were completely shielded from the user this was no issue, but since they are made from aluminium and in screwed to the aluminium housing… My guess is that the issue lies there.
How to protect the inputs of the AD8226 from ESD without disturbing the very fine readings from the load cells (wheatstone bridge).
And should I also protect the V and GND to the load cells?
Is the use of resistors sufficient or should I use diodes? And which will do what to the circuit and protect what?
Can anyone point me in a good direction or tutorial or explain the basics to me?
And maybe someone might find it interesting to have a look at my schematic and product and tell me what to do.
Thanks in advance!