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DS90UB954-Q1: Question about lock time

NOBUO FUJIHARA
Genius 9355 points
Part Number: DS90UB954-Q1

Hi team,

My customer sees lock time varies widely during power-up sequence, with 953 + 954 (coax) synchronized configuration.

Lock time varies from 20ms to 100ms under room temp configuration.

What can you guess the cause for this variation?

Best regards,

  • 0
    TI__Guru** 103215 points

    Hello Nobuo,

    What is the exact power up sequence being used to test this? Is the serializer kept powered on and then the deserializer power is toggled? Or is the deserializer left on and the serializer power is toggled? The first one would be a more deterministic test because the AEQ will always start at the lowest gain setting rather than the second case. If you toggle just the serializer power, the deserializer AEQ could be at a different setting than the lowest depending on when the serializer data becomes available because the deserializer AEQ is always cycling through gain values when it is unlocked trying to find lock. 

    But 20-100ms is not unreasonable based on default 954 settings. Please see the datasheet page 14 for lock times. If you would like to reduce the maximum lock time then it is recommended to constrain the AEQ to a smaller range of values. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Genius 9355 points

    Hi Casey,

    Thanks for your prompt support, I could understand the reason why lock time varies when 954 powered-on later than 953.

    I share it with customer.

    Best regards,

    Nobuo