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TMS570LC4357: DCC#24 Errata

Christopher TRITANT
Expert 1080 points
Part Number: TMS570LC4357

Hello,

Regarding the erreta sheet "DCC#24" in TMS570 LC4x (Revision B) errata sheets document (SPNZ232A (May 2016)), the condition when the errata occurs is in single shot mode whereas the errata sheet "SSWF021#45" (PLL Fails to Start) including the workaround implementation requires to use the DCC in single shot mode.

Moreover, the "DCC#24" workaround, thta consist in making two measurements and subtracting,  does not seem to be applied in the "SSWF021#45" workaround.

Could tell us more information about these two errata and workaround ?

Best regards,

Christopher

  • 0
    Expert 1080 points
    * "[...] the erreta sheet "DCC#24" in TMS570 LC4x (Revision B) errata sheets document (SPNZ232A (May 2016)), the condition when the errata occurs is in single shot mode and the count value captured is not from VCLK [...] "
  • 0 in reply to Christopher TRITANT
    Expert 1080 points
    Hello,

    Could you provide us an answer or do you need information about our request ?

    Best regards,
    Christopher
  • 0
    TI__Mastermind 49120 points
    Hi Christopher,

    Sorry for missing this post from last week.

    DCC#24:

    If you use the single-shot mode (one-time measurement versus continuous monitoring) of the DCC to measure a signal frequency using a known clock signal, the expected behavior is that the non-zero counter freezes when the other counter becomes zero. This is not the case as the start/stop operations of the counters are synchronized to VCLK. This leads to a time offset and eventually to an incorrect measurement of the frequency of the signal being measured. The workaround is to perform multiple measurements and discard any outliers.

    SSWF021#45:

    You are correct in that the suggested workaround for DCC#24 is not implemented in the workaround for the SSWF021#45 issue. I will check if there is any plan to update the application note that details the SSWF021#45 erratum: www.ti.com/.../spna233a.pdf

    Regards,
    Sunil
  • 0 in reply to Sunil Oak
    Expert 1080 points
    Hello,

    Could you provide us an answer or do you need information about our request ?

    Best regards,
    Christopher
  • 0 in reply to Christopher TRITANT
    TI__Mastermind 49120 points
    Christopher,

    There is no plan to update the app note (spna233) at this time. I will let you know if this plan changes.

    Are there any other open questions related to these two errata that are unanswered?

    Regards,
    Sunil