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MSP430FG6626: External ADC Reference

Chris Hamilton
Prodigy 20 points
Part Number: MSP430FG6626

We currently have an MSP430FG6626 in our design and we ended up connecting an external 3V reference to the P5.0_VREFBG_VeREF+ pin.  Upon further reading in the datasheet, although not totally clear to me, it would appear that 1.5V is the maxmimum voltage allowed... am I reading that right?  Is there risk of damage to the part if we leave 3V there and only use the internal reference on the part?  Trying to understand if we need to rework a bunch of boards to fix this, or if it's safe to leave it

Thanks

  • 0
    TI__Guru 63821 points

    Hi Chris,

    That appears to be correct.  Yes, there is a risk that overtime the higher voltage could damage the part, but operating with that high reference voltage will most likely not produce the correct outputs.  Let me double check on this...

  • 0 in reply to Dennis Lehman
    Prodigy 20 points

    Thanks Dennis for the quick reply... any more word on this in terms of potential damage to the part if left alone?  Like I said, I think we can adapt to just use the internal ref for now, but would like to know about implications for permanent damage.

    Thanks!

  • 0 in reply to Dennis Lehman
    Prodigy 20 points

    Thanks Dennis for the quick reply... any more word on this in terms of potential damage to the part if left alone?  Like I said, I think we can adapt to just use the internal ref for now, but would like to know about implications for permanent damage.

    Thanks!

  • +1 in reply to Chris Hamilton
    TI__Guru 63821 points

    Hi Chris,

    When operating the device out of spec it is difficult to say if/when/how it will fail.  If you are not using the CTSD16, then it shouldn't be an issue.  If you look at the 12-bit DAC 's reference voltage spec can be AVCC = DVCC.

  • 0 in reply to Dennis Lehman
    Prodigy 20 points

    Thanks again for your help Dennis.

    It does appear that just the presence of this voltage on the pin, despite how the pin is configured, causes bad measurements and other strange performance issues.

    Our fix on our end is to decouple that completely from the pin and move on using the internal reference.

    Thanks again for your help

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