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How to use AD9557 for Synchronous Ethernet?

Question asked by Wojtek on Apr 5, 2012
Latest reply on Apr 9, 2012 by Wojtek

Hello: we plan to recover the clock from the Synchronous Ethernet (SE) using MAX24288, whose output clock jitter is quite bad (a nanosecond!). So we need to clean that clock. Our jitter requirement is pretty modest. A few tens of ps will be perfect. We do not need to go to single picoseconds.


Our candidate clock cleaner could be AD9557, whose data sheet mentions SE as one of the applications on page 1. Unfortunately, besides mentioning SE, there is no other reference to SE in the AD9557 Data Sheet. (A very untypical situation for Analog Devices, whose Data Sheets are usually very good.) The AD9557 press release says that the part can be pin-strapped for SE, but there is no further clue. Furthermore, when looking at the Eval Board, there is BOM and the schematics, but there seems to be no software to drive it, even though the eval board has a processor onboard.


1. Are there any App Notes which would illustrate how to use the part for SE clock cleaning?

2. What is the jitter performance of the cleaned clock?

3. How to configure the part? How to pin strap the part for the SE?

4. Is it the best / simplest part? Are there better / simpler clock cleaners? (Ideally no programming!)

5. Any gotchas?

6. Any sugestions whether ADI is offering an alternative to MAX24288?


Thank you! -- Wojtek