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MAX3232E: Potential Causes of R1IN (pin 13) Failure

Roy Powell
Prodigy 10 points
Part Number: MAX3232E

Hi All,

I have a board that uses the MAX3232E chip to drive communication between an on-board micro controller and a host controller that is connected through a cable.

This board has been in production and working well for about 4 years, but over the past year I have started to see failures where the R1IN pin has a low resistance path to ground (about 2 to 200 ohm).

This path to ground seems to be internal to the 3232E chip, as the path goes away if I remove the chip from the board.

About half of the failures occur during a final integration test, and the other half occur in the field within a month or so.

For now I suspect the issue lies with our board manufacturing and/or testing.

Does anyone know what conditions might cause this sort of failure?

REF: schematic around 3232E chip:

REF: Voltage measurements on 3232E chip:

Thanks,

Roy

  • 0
    TI__Mastermind 25705 points

    Roy,

    Is MAX3232E used at both sides of communication? Do you think there could be any change of the RIN input signal? RIN pins work with up to +/-25V. Another place to check is grounding. Although the issue is at RIN, I'm not sure if big ground potential difference could happen to cause the damage. 

  • 0 in reply to Hao L
    Prodigy 10 points

    Hi Hao,

    We use a MAX208CDW on the host side communication. I am fairly confident that the RIN input signal has not changed, but a grounding issue does seem plausible since RIN is the only externally driven pin. It could be possible that one of our integration test cables has a grounding issue... Thanks for the suggestion.