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DS90UB954-Q1: DS90UB954-Q1

Siva Rama Krishna Yerkareddy
Prodigy 70 points
Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: ALP

Hello ,

Using 954/953 SerDes in our system and  facing issues at clod (-40C) temperatures. below are the observations While debugging with ALP tool.

1) observed LOCK changes with default Serdes Settings

2) Performed margin analysis and observed no margin meaning No greens , but the margin improving when the temperature raises

3) Using Spread spectrum clock as reference clock to the 954 Deserlaizer and if we disable the Spread option we are seeing More green and Lock is stable at cold.

I would like to know if this behavior is because of the Spread spectrum clock .

Thanks

Siva

  

  • 0
    TI__Mastermind 30515 points

    Hello Siva,

    This behavior would be expected for some system design. From above issue descriptions and analysis, basically we can confirm this is on high speed serial link margin design issue. The SSC would impact the link jitter margin also the system level noise / jitter is exacerbated, so you can see the green block is changed with SSC setting and temp. variation. But I would hope you can understand this issue from the total system level on the link margin issue in low temp. and SSC enabled condition.

    From the total serial link design standpoint, please make sure that you need reduce the jitter to the expected level and make the system have enough margin to tolerate the environment change such as temp., process and power supply variation. some points are:

    1. transmission channel performance including connector and cable, d/s has S11/S21 parameter request, pls refer to it.

    2. PoC design and the component selection, pls refer to TI's recommendation in d/s or EVM board (BOM list)

    3. power supply noise rejection (maximum pp spec. in d/s)

    4. external XO performance and the SSC modulation and deviation parameter.

    best regards,

    Steven

  • 0 in reply to Steven(Shenzhen) Shi
    Prodigy 70 points

    Hello Steven,

    Thanks for your reply . We followed the TI recommendation as per TI D/S and we have measured the Eye diagram & Jitter Measurements  and Power supplies ripple , all are with in the range .

    We replaced Spread spectrum oscillator with regular oscillator on  two failed boards at cold and these failed boards are working normally at cold for 20 hours.

    Thanks

    Siva

  • 0 in reply to Siva Rama Krishna Yerkareddy
    TI__Mastermind 30515 points

    Siva,

    From your test, it should be link margin design issue. please help provide the test plots and the register dumping when error is reported for further analysis. thanks.

    best regards,

    Steven