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TMS320F280049: PLL Errata :" PLL May Not Lock on the First Lock Attempt" question

Huihuang Chen
Expert 4060 points

Part Number: TMS320F280049
Other Parts Discussed in Thread: C2000WARE

Hi Champ,

For F28004x  PLL errata : PLL May Not Lock on the First Lock Attempt,

Could you help on following question from customer :

1.This issue  related to customer HW  design or not?

2.If PLL not locked, the CPU will  be no clock or run with the OSCCLK?

3.Does F28002x has the same PLL errata issue?

  • 0
    TI__Mastermind 43210 points

    Hi Johnson,

    Please see responses below:

    1.This issue  related to customer HW  design or not?

    - This is not related to customer HW.  This is a result of the internal PLL on the F28004x not able to start immediately on a very limited number of units.  The errata provides a workaround that is released in C2000Ware to overcome this startup issue.  Please advise the customer to use the PLL start up functions InitSysPll() or SysCtl_setClock() provided in C2000Ware to avoid the startup issue.


    2.If PLL not locked, the CPU will  be no clock or run with the OSCCLK?

    - The CPU will be clocked by OSCCLK


    3.Does F28002x has the same PLL errata issue?

    - No, F28002x uses a more robust PLL design that does not have the start up issue

    Regards,

    Joseph

  • 0 in reply to Joseph Casuga
    TI__Expert 4060 points

    Hi Joseph,

    The InitSysPll() function used DCC to check PLL lock, but DCC also has "DCC: Single-Shot-Mode Operation May End Prematurely" errata.

    from the code it is seems  the DCC errata didn't implement in IsPLLValid() function.

    So customer need to add the DCC workaround by themself?

  • 0 in reply to Huihuang Chen
    TI__Expert 4060 points

    Hi Joseph,

    For F28004x PLL Errata :" PLL May Not Lock on the First Lock Attempt", could you advise the failure ratio?

    just some chip with this issue, or every chip may has this issue?

    One more question, does F2802x has the same PLL issue --PLL May Not Lock on the First Lock Attempt?

  • 0 in reply to Huihuang Chen
    TI__Mastermind 43210 points

    Hi Johnson,

    If customer used the latest InitSysPll() function from C2000Ware, then the DCC routine would have taken care of the errata.  If customer wrote their own routine, can you send the code snippet they used for checking the SYSCLK using DCC so we can check?

    As for the PLL locking errata, this happens only on a very low volume of chips if the PLL errata workaround is not implemented.  If the PLL errata workaround (lock several times + use DCC to check the SYSCLK frequency) is used the number of units not locking would be further reduced (very very low PPM).  F2802x uses a different PLL so it is not susceptible to the locking issue.

    Regards,

    Joseph

  • 0 in reply to Joseph Casuga
    TI__Expert 4060 points

    Hi Joseph,

    Could you advise which version of C2000ware have taken care of DCC errata in InitSysPll() function?

    in  C2000Ware_3_02_00_00, does implement the DCC errata.

  • 0 in reply to Huihuang Chen
    TI__Mastermind 43210 points

    Hi Johnson,

    My apologies.  I thought the latest C2000Ware version had the workaround for the DCC singleshot issue.  We will file a ticket to get this implemented.  The chances of the DCC singleshot issue happening is also very low, but it will be good to add it to the program.  During development and debug of the InitSysPll() function, we have not observed the two conditions described in the DCC errata, hence was not implemented.

    Regards,

    Joseph