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AM2434: Question to Absolute maximum ratings

Koichiro Tashiro
Mastermind 22945 points
Part Number: AM2434


Tool/software:

Hi,

Below is Absolute Maximum Ratings in Datasheet (SPRSP65G).


My customer is asking what is the reason the maximum voltage at IO pin is IO supply voltage+0.3V.
Is this to prevent an internal ESD diode from turning on?
If so, what is a problem with the internal ESD diode turning on?

Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru 63235 points

    Yes, the ESD protection circuits will turn on if the input is greater than IO supply voltage+0.3V.

    We do not allow injection current through the ESD protection circuits because they were only designed to protect the device from short-duration ESD events that occur during device handling and PCB assembly. The ESD protection circuits are not designed for steady-state DC current or provide any system-level ESD protection once the device has been installed on a PCB.

    Regards,
    Paul

  • 0 in reply to peaves
    TI__Mastermind 22945 points

    Hi Paul,

    peaves said:
    We do not allow injection current through the ESD protection circuits because they were only designed to protect the device from short-duration ESD events that occur during device handling and PCB assembly.

    Do you have specific number for "short-duration"?
    50msec duration would damage the device?

    Thanks and regards,
    Koichiro Tashiro

  • +1 in reply to Koichiro Tashiro
    TI__Guru 63235 points

    We do not allow any injection current from an IO voltage potential greater than IO supply voltage+0.3V, for any period of time.

    My comment about short-duration was simply a reference to the typical ESD event profile that falls within the limits defined by the ESD standards listed in the ESD Rating table of the datasheet. As mentioned before, the ESD circuits were only designed to protect the device from ESD events similar to what would be introduced by a Human Body Model to account for device handling and a Charged Device Model to account for PCB assembly equipment. The ESD circuits were not designed to protect the device from system-level ESD events that occur after being installed on a PCB. However, the ESD circuits are still connected to the IOs. So, we must ensure the circuits are not damaged from unexpected injection current.

    Regards,
    Paul