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DS250DF230: Basic question about DFE and PFD

Takumi Suzuki1
Mastermind 8610 points
Part Number: DS250DF230

Tool/software:

Hi,

Let me ask you following basic questions.

I do not understand well about the behavior of DFE and PFD.

About PFD, I did not find the explanation on the datasheet..

Q1) What is DFE and how to use it?

In particular, datasheet 50 page, register address 1E, 3bit, "DFE_PD" setting.

I do not understand well the behavior difference between "1" and "0" setting.

Q2) What is PFD and how to use it?

In particular, the same register address of DFE, 1E, 0bit, "PFD_EN_PD" setting.

Will you tell me, what is the roll of PFD and how does it work?

What is the difference behavior between "1" and "0" setting.

How should it normally be set?

Thank you for your support.

Best Regards,

Takumi

  • +1
    TI__Mastermind 36113 points

    Hi Takumi-san,

    Thanks for reaching out with your questions.

    I'd like to encourage you to review the programming guide for this device.  This has common configuration sequences and additional details not found in the data sheet.  If you don't already have access, you can locate it here:

    https://www.ti.com/drr/opn/DS250DF230-DESIGN

    1. DFE (decision feedback equalizer) is a digital filter used in the retimer receiver signal chain.  This filter is automatically equalized during CDR lock when using adapt modes 2 and 3.

    • DFE_PD is DFE power down.  When 1, DFE is disabled.  When 0, DFE is enabled.  For adapt modes 0 and 1, this should be 1.  For adapt modes 2 and 3, this should be 0.

    2. PFD refers to phase frequency detector.  This is part of the VCO / PLL functional block of this devices.

    • In a typical application, it is not recommended to adjust registers pertaining to PFD.  The default values are adequate.
    • The primary configuration relating to VCO / PLL / CDR configuration is configurating the data rate.  For common rates, this can be set with register 0x2F.  For uncommon data rates, the rate can manually be set with registers 0x60 - 0x63.  Please see sections `7.6 Standard Data Rate Settings` and `7.7 Manual Data Rate Configuration` within the programming guide.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Mastermind 8610 points

    Hi Drew-san,

    Thank you very much for your kind reply.

    Many thanks!

    Regards,

    Takumi