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Original question:

DS250DF230: Basic question about DFE and PFD

DS250DF230: Additional questions

Takumi Suzuki1
Mastermind 8610 points
Part Number: DS250DF230

Tool/software:

Hi,

 

About related question as below, let me ask you some questions for my understanding.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1480049/ds250df230-basic-question-about-dfe-and-pfd/5684192#5684192

 

1) 0x1E 3bit DFE_PD

You taught me followings,

  - For adapt modes 0 and 1, this should be 1.

  - For adapt modes 2 and 3, this should be 0.

But if we set the different value, how does this device work?

That is to say,

 - In case this bit is set to 0 when adapt mode 0 and 1

 - In case this bit is set to 1 when adapt mode 2 and 3

 

2) 0x1E 0bit PFD_EN_PD

The same question as above,

In case this bit is set to 0, what will happen?

Thank you for your support again.

Best Regards,

Takumi

  • +1
    TI__Mastermind 35973 points

    Hi Takumi-san,

    1. Relating to DFE_PD

    In case this bit is set to 0 when adapt mode 0 and 1: We expect that DFE will be enabled, but will not be automatically adapted.

    In case this bit is set to 1 when adapt mode 2 and 3: We expect that DFE will be disabled

    2. This will impact CDR lock behavior.  We do not recommend setting this to 0.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Mastermind 8610 points

    Hi Drew-san,

    Many thanks for your reply !

    Sorry, one more question as  below, please.

     - In case this bit is set to 0 when adapt mode 0 and 1: We expect that DFE will be enabled, but will not be automatically adapted.

       My understanding is that DFE seems to be enabled but do nothing... Is this correct?

    - This will impact CDR lock behavior.  We do not recommend setting this to 0.

       I do not understand well, when(what kind of situation) should we set this bit to 0?

       I suppose it seems not to be needed this bit setting...??

    Thanks and Best Regards,

    Takumi

  • +1 in reply to Takumi Suzuki1
    TI__Mastermind 35973 points

    Hi Takumi-san,

    1. DFE will be enabled.  It will do nothing if the DFE tap values are set to 0.  If they have been set to non-zero values (either manually or through starting in adapt mode 2/3 and switching to 0/1), then DFE will have an impact on the signal.  Unless we are investigating an adaptation issue, we typically recommend disabling DFE for adapt mode 0 and 1 and enabling DFE for adapt mode 2 and 3.

    2. We expect that you will not need this bit setting during typical operation.  The only case where it might be used is when debugging some rare CDR lock issue.  Personally, I have not supported an issue that required setting this bit to 0.  I would recommend leaving it at 1.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Mastermind 8610 points

    Hi Drew-san,

    Thank you very much for your kind support !

    I understood.

    Regards,

    Takumi