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[ ADS1248 ] External ESD Protection Guideline

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: ADS1248, TPD2E1B06

[ ADS1248 ] External ESD Protection Guideline

Hi,

I have learned many things from following posts with regards to external ESD protection circuit.(It's not easy and simple!).
My customer has used a varistor "ERZV10D112" from Panasonic for existing model and didn't see any issues. Now they are working on new development and try to reduce the size.

ERZV10D112 : Varistor Type: D Series:V
industrial.panasonic.com/.../ERZV10D112

Can you comment on this protection idea? Also, it's great if you have something new ideas with regards to external ESD protection.

Thanks,
Ken

Reference for external ESD protection circuit

ADS1248: What is the actual ESD protection level on the analog inputs and GPIOs?
e2e.ti.com/.../257097

ESD Protection in ADS1248
e2e.ti.com/.../829867


RTD measurement using ADS1248 : Accuracy issues during long run
e2e.ti.com/.../1715313


  • 0
    TI__Guru* 93715 points
    Kenichiro-san,


    I'm not sure that the varistor is good for ESD protection. Usually ESD is a discharge of a high voltage spike of very short time duration (usually in nanoseconds). A varistor is usually specified in maximum energy discharged in a longer period of time (in microseconds). With this difference in time scale, I think that the a varistor wouldn't be a good ESD protection device. It might be better suited for over-voltage protection where the voltage may not go so high, and the inputs may be held to a higher voltage for a longer duration.

    For the analog inputs, a ESD structure should be low leakage since the current may react to series resistances to cause a voltage error.In some cases, there may be large capacitances associated with the ESD structures, but in most cases I don't think it is a problem. In the past, we've recommended something like a TPD2E1B06 as a possible ESD solution. It has a good ESD rating, low leakage, and low parasitic capacitance.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Mastermind 9165 points
    Hi Joseph,

    Thank you for sharing your thought with me!It's valuable for me.
    I would suggest our TPD solution rather using varistor for ESD protection.

    Thanks,
    Ken