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DS110DF410 - Adaptation operation during no CDR lock

Kawai
Guru 19785 points
Other Parts Discussed in Thread: DS110DF410

Hi Team,

Is there a flow chart of the device operation from power up to signal output ?

I am asked from our customer how the CTLE/DFE adaptation block operates when there is an active signal but no CDR lock.

I am understanding that after device detects input signal, each block (CTLE/DFE/CDR/Driver) will return to normal mode from power down. When the input signal is active and is out of the programmed range, does the device repeats CTLE and DFE adaptation until CDR get locked ?

I believe CTLE adaptation block repeats optimization by changing the gain value from CTLE Adaptaion Index 0 to 31, and then 0 to 31 again, until CDR locks.

Thanks and Best Regards,
Kawai

  • 0
    TI__Expert 3175 points

    Hi Kawai,

    We are looking into this case. Someone will respond to your post soon.

    Regards,

    TK Chin

  • 0
    TI__Intellectual 1705 points

    Hi,

    There are alot of circuit blocks in the the device that are used to monitor the input signal before it delares CDR lock and output the retimed data signal. All of these are running in parallel while the CTLE is adapting.

    If there is an input signal and CDR is not locked. The CTLE value will continue to change. The register 0x03 will be updated unitl the CDR lock is declared.

    The CTLE and DFE adaption will continue while the CDR is trying to lock to the input signal frequency. The CTLE adaption will step thru the 0-31 EQ index settings (reg 0x40 to 0x5F) to select the optimal EQ setting by using the EOM. When all the checking are met, it would then declare CDR lock and the adaption would stop.

    Regards,

    Michael

  • 0 in reply to Michael Hinh
    Guru 19785 points

    Hi Michael-san,

    Thank you for your detail explanation. Please let me confirm one thing.

    > If there is an input signal and CDR is not locked. The CTLE value will continue to change.
    > The register 0x03 will be updated unitl the CDR lock is declared.

    Specifically, does DS110DF410 continue and REPEAT the CTLE adaptation from 0-31 EQ index settings until CDR lock, as long as there is active input signal ?

    What we needed to know is that if there is a case when DS110DF410 would give up to lock to the input signal. I believe there is no such case, but please let me ask you our customer question.

    Thanks and Best Regards,
    Kawai

  • 0 in reply to Kawai
    TI__Intellectual 1705 points

    Hi Kawai-san,

    Yes, the CTLE adaption will continue and repeat until CDR is locked.

    There are 2 conditions that I can think of which can cause the CDR not to be able to lock even when there is a good high speed input signal.

    1. The 25MHz REFCLK is used for the CDR to acquire lock and if it is not present, the CDR will be able to declare  lock.

    2. In the channel register, the reg 0x0A, bit [3:2], when both bits are set to 11, the CDR is in reset (powered down).

    Regards,

    Michael

     

  • 0 in reply to Michael Hinh
    Guru 19785 points

    Hi Michael-san,

    I understand.

    I greatly appreciate your support.

    Best Regards,
    Kawai