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TM4C1231C3PM : Absolute maximum rating of VADCIN

alpha
Expert 2530 points

Hi

VDDA is specified that absolute maximum rating is max 4V.
How can I estimate VADCIN of maximum rating?
Is that same VDDA of abosolute maximum rating?

Regards.

  • 0
    Guru 26105 points

    Hi,

    If VADCIN is maximum ADC input voltage, then you should realize that the ADC code is limited by the reference voltage; over that level, no code (or saturation).

    Petrei

  • 0
    Guru 27665 points

    You do realize that the 4V rating is a stress rating not an operating rating?

     

    Robert

  • 0 in reply to Robert Adsett
    Expert 2530 points

    Yes

    I realize that the 4V is not a operating rating.
    I would like to check VADCIN of absolute maximum absolute rating.

     Regards

  • 0 in reply to alpha
    Guru 27665 points

    alpha said:
    I realize that the 4V is not a operating rating.
    I would like to check VADCIN of absolute maximum absolute rating.

    Good, many times when I hear a question like that the unspoken assumption is that you can actually operate the IC at that voltage.

    The data sheet does not call out a separate stress rating for the Analog pins, but considering that they share digital functions I would expect them to share that protection (there are a few pins w/o the standard protection you'll have to check them separately if they share analog function).  That is, however, only an educated guess.  You will need an answer from TI if you want something meaningful.

    On a separate note though, since these are analog inputs I would expect them to be relatively heavily filtered and you should see no high frequency that the stress rating would refer to and you reallly do not want to see DC values above the operating range (it is a stress rating after all).  If you do see high frequency spikes the A/D is going to be vulnerable to producing bad results in any case even if the spikes are within the operating voltage range and I do speak from experience on this.

    Robert

  • 0 in reply to Robert Adsett
    TI__Guru 58650 points

    Hi Alpha,

    The Absolute Maximum Ratings table shows that the input voltage on the GPIOs, should not go above 5.5 V.  Robert is correct that the ADC inputs are on GPIO pads and are subject to this specification as well as the specifications in the Recommended GPIO Pad Operating Conditions table in the Electrical Specifications chapter in the data sheet. 

    Regards,

    Sue