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SPNZ195D Errata ADC#1

Charles Johnston
Expert 2690 points

Hello,

One workaround for this errata is:

"Limit the analog input upper limit to be lower than (VDDA - 0.3V)."

Is VDDA the same as VCCAD?

Also - the two figures have black text on black background - I assume they should look like the ones supplied in this thread:

http://e2e.ti.com/support/microcontrollers/hercules/f/312/t/314565.aspx

Thanks, Charlie Johnston

  • 0
    TI__Guru 68920 points

    Charlie,

    Yes, VCCAD is the correct name.   Sometimes we refer to it as VDDA internally and this creeped into the errata.

    Sorry about the picture being blacked out.  That really isn't acceptable.  I believe it should be the same image that Sunil posted but I am assigning this to Sunil to confirm since he is sourcing the errrata information for this issue.


    Sunil, were there any changes between the posted version of the PDF http://e2e.ti.com/support/microcontrollers/hercules/f/312/t/314565.aspx and what you sourced for the errata? 

     

  • 0 in reply to Anthony F. Seely
    Expert 2690 points

    Hi Anthony,

    Another clarification:

    "Limit the analog input upper limit to be lower than (VDDA - 0.3V)."

    Does this refer to the unique input, the shared input, or both?

    Thanks, Charlie

  • 0 in reply to Charles Johnston
    TI__Guru 68920 points

    Charlie,

    My understanding is that the shared input channels need to be limited in input voltage range otherwise they could affect the conversion result of (any) channel on the other ADC. 

    But I asked Sunil to comment on this thread and he is the best person to also confirm this point.

  • 0 in reply to Anthony F. Seely
    TI__Mastermind 49120 points

    Anthony,

    Yes, the issue is caused by injecting current into the shared-input channel. The workaround also requires that the input level on the shared-input channel be limited to (VDDA - 0.3V). We will make this update to the description in the errata documents.

    As for the image, it was supposed to be identical to what I had posted on the related forum thread. Need to check what happened to the color scheme and correct it.

    Regards, Sunil