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Original question:

DS90UB914A-Q1: Adaptive Equalizer Details

DS90UB914A-Q1: Unable to Capture CMLOUT Waveform during BIST

Kenichiro
Mastermind 9165 points
Part Number: DS90UB914A-Q1
Other Parts Discussed in Thread: DS90UB913A-Q1

THIS IS RELATED TO THE ISSUE OCCURRING AT ONE OF MAJOR OEM NOW.

[ DS90UB914A-Q1 ] Unable to Capture CMLOUT Waveform during BIST

Hi,

My customer has found several units that are not able to capture the CMLOUT waveform during BIST mode.

- Several Units: Shown distorted camera movie. Even with BIST mode, LOSS and PASS pins are unstable. Unable to capture valid eye on CMLOUT.
- Known Good Unit: Normal camera movie. Stable LOSS and PASS pins during BIST mode and clear eye on CMLOUT. (used with same camera and cables)

From customer debug experiment, so far it's assumed that DS90UB914A-Q1 is one of the potential cause of showing the behavior above.
However, we are still looking all of the potential cause.

Do you have any ideas that DS90UB913A-Q1 could cause this kind of failure at receiver side?
I would say,
- the jitter on input PCLK to UB913A
- not enough PoC filtering on camera side would cause line/frame noise go back to the receiver side.
and so on...

Even your comments and ideas are helpful at this moment.
I know that I need to share more details which are asked on separate thread.

Thanks,
Ken

  • 0
    TI__Genius 10475 points
    Ken,
    Is this related to the same issue for which you were asking about AEQ information yesterday on the other E2E thread?
    Yes we need some additional information to provide any guidance.
    Can you describe what you mean by "unable to capture valid eye on CMLOUT"? Does the CMLOUT eye look not as good in the failing case?
    Have they done A-B-A swap to switch the known good unit between boards to see if the failure follows the unit or the board?

    Unstable LOCK and PASS can be because of a variety of reasons - power supply noise, input PCLK quality not good or too jittery etc.
  • 0 in reply to Palaniappan Manickam
    Mastermind 9165 points

    Hi Palaniappan,

    Thank you for your support, yes, this is also related to the issue.
    I will compile the information onto another thread and close this.

    > Can you describe what you mean by "unable to capture valid eye on CMLOUT"? Does the CMLOUT eye look not as good in the failing case?
    > Have they done A-B-A swap to switch the known good unit between boards to see if the failure follows the unit or the board?

    This means that, even with same known good camera and cables, a suspected unit cannot show clear eye from CMLOUT, while other unit can.
    We are still performing the debug and have not performed ABA swap yet. Yeah, it would be the next step...

    Thanks,
    Ken