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Original question:

LM139: ESD

LM139AQML: Negative Transient Question

Oscar Jara
Prodigy 10 points
Part Number: LM139AQML


Tool/software:

Let me provide you with a quick background. After running an ESD analysis (+/-4kV transients) on my comparator circuit I noticed I didn’t have any ESD issues. However, I did see a negative transient exceeding the data sheet note of not allowing the inputs to be driven below ground. In this instance, it reached as Low as -80volts.

 

I would like to know from you what problems (internal shorts or opens) would the comparator exhibit from that great of a negative transient.

  • +1
    TI__Guru 63456 points

    Hello Oscar,

    We have to say it will destroy the input, or cause parametric shifts as you are hammering the input structure and associated parasitic devices.You may not notice the issue right away (did you verify the offset voltage, supply current and/or bias currents did not change?

    We cannot condone exceeding the Abs Max ratings.

    These devices are from the days where ESD was not a problem (1970's), therefore, they do not have internal dedicated ESD structures. It's just the "toughness" of the old process that allows it to survive the 500-1000V strikes.

    We would recommend external clamps or ESD protection devices if the inputs will be subjected to possible ESD. Remember the protection devices cannot be bi-directional and need to clamp negative.