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DP159 - Digital Lock Detect Output

Kawai
Guru 19785 points


Hello Team,

Our customer is using DP159 as DisplayPort retimer. They are monitoring "Digital Lock Detect Output" to confirm CDR(PLL) lock status. They are saying that, in their evaluation, this bit sometime showed "locked" even when input signal is turned off.

Programming sequence is following Application Report : SLLA358.

[Q1]
Would there be a possibility that above symptom may happen ?

[Q2]
Would it be better to confirm both "PLL Analog Lock Indicator" AND "Digital Lock Detect Output" ?

Best Regards,

Kawai

  • 0
    TI__Mastermind 23815 points

    Hi Kawai-san,

    This could happen, that's why they should only enable PLL when receiving TPS1.

    You can have more infromation about it in section 4.3 of Application note:DP159 as DisplayPort Retimer.

    Regards

  • 0 in reply to Moises Garcia
    Guru 19785 points
    Hello Moises-san,

    Thank you for your continuous help for our DP159 questions.

    Our customer is following "Application note:DP159 as DisplayPort Retimer" procedure. After following the procedures for DisplayPort retimer, DP159 seems to be operating correctly, however, when they disconnect source side DisplayPort connector, DP159 still showed "Locked" in Digital Lock Output Status.

    Could this happen ? Do you have any idea ?

    Best Regards,
    Kawai
  • 0 in reply to Kawai
    TI__Mastermind 23815 points

    Hi Kawais-san,

    After removing DP source, you need to run reinitialize PLL, RX and Tx setting, are you doing it?

    This is in section 4.1 of application note.

    Regards