cdce62005 holdover mode

Yifan Yang

Other Parts Discussed in Thread: CDCE62005

Hi :

Could you please tell me where I can find information about cdce62005 holdover mode ?At page 1 of the datasheet it mentions "Oscillator Holdover Mode", but I can't find anything about this.

Another question about the SERDES Startup Mode, the recovered clock rely on a stable link, after clock switch before cdce62005 lock to the recovered clock, the data link is not stable any more, thus the recovered clock becomes unstable, how can we implement such clock switch ?

Thank you very much for your kindly help.

Best regards!

over 13 years ago

0 Julian Hagedorn over 13 years ago

TI__Mastermind 20900 points

Hello Yifan,

The Oscillator Holdover mode is described at page 42 in the datasheet. It means that if an input fails it can be switched automatically to the next input. (Smart Mux)

Still thinking about the SERDES problem.

Best regards,

Julian

0 Yifan Yang over 13 years ago in reply to Julian Hagedorn

Prodigy 210 points

Hi Julian：

Thank you very much, I thought holdover was a function that can keep output alive while losing input, seems I'm wrong.

For the SERDES, the key point is how can cdce62005 lock to the recovered clock fast enough that not affect (or seems not affect) the output. I observed a lose lock happened 100us after a clock switch, I think 100us is enough for locking, it means before locking, the output is keeping changing .Do we need a wider loop bandwidth ?

Best regards!

0 Yifan Yang over 13 years ago in reply to Julian Hagedorn

Prodigy 210 points

Hi Julian:

I solved the problem by setting a narrow loopfilter bandwidth, actually if the cdce62005 slowly lock to the switched clock, it works fine.

But now I have a problem of fixed latency, I will open a new post.

Thank you very much for your kindly help.

Best regards!

yifan

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cdce62005 holdover mode