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DS90UH948-Q1: Why does Lock Status become Low when CML TX powered down

KEISUKE KANDA
Prodigy 30 points
Part Number: DS90UH948-Q1

Tool/software:

Hello,

I'm trying to use a Pattern generator function in DS90UH948-Q1.

In that evaluation, beased on the NOTE in datasheet below,
   
   NOTE: CML TX must be powered down prior to enabling Pattern Generator
I modified CML_OUTPUT_CTL3 Register from 0x00 to 0x01.

However, the deserializer changed Lock status output from low to high at the same time of command issued.
I would like to know the reason why the Lock Status became low output when CML TX powered down.

We also want to know how to keep lock status high even when we make CML TX powered down.
That's because when the low lock status is detected, the overall system of our product will attempt to power down all components, including the deserializer, preventing us from continuing the evaluation.

  • 0
    TI__Mastermind 19295 points

    Hi Keisuke,

    KEISUKE KANDA said:
    However, the deserializer changed Lock status output from low to high at the same time of command issued.
    KEISUKE KANDA said:
    I would like to know the reason why the Lock Status became low output when CML TX powered down.

    This may be intentional from the perspective of the pattern generator function of the DS90UH948-Q1, as we do have a note about this in the datasheet:

    KEISUKE KANDA said:
    We also want to know how to keep lock status high even when we make CML TX powered down.

    The Lock status is an indicator that the SER device is connected over the forward channel to the DES device, at any time the device enters BIST mode for pattern generation, it is now locally defining an output video which does not need the upstream device.

    You may change the function of lock to indicate SER upstream link status, just know this may not reflect the actual indication of stable established forward channel between the devices:

    (Main Page register 0x34 bit [6] = 1).

    Please let me know if you have any further questions.

    Best,

    Miguel

  • 0
    Prodigy 30 points

    Hello, Miguel

    Thank you for your reply and explanation.
    We will reconsider how to use of the Pattern Generator function for our evaluation based on your comments.

    Best regards,
    Keisuke Kanda

  • 0 in reply to KEISUKE KANDA
    TI__Mastermind 19295 points

    Hi Keisuke,

    You're most welcome, please let me know if you have any additional questions regarding this setup.

    Best,

    Miguel