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Old 06-30-2010, 09:46 PM
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Top Jimmy Top Jimmy is offline
Join Date: Oct 2005
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Default Re: Loop Sync issues

Originally Posted by mightyduck View Post
it wouldn't hurt, [and might help], to terminate the 192s.
The 192 word in is terminated internally.

the usual procedure would be to use hardware termination on each of them if they are receiving external clock.
Only if the clock input is unterminated internally.

with the amount of devices you have to clock, i would not create little sub-chains within the configuration [as in using loop sync for the 192s, or even daisy chaining them with straight word clock].
Daisy chaining word clock I/O is not a good idea. Each generation would be adding another layer of PLL along with its inherent error. The last device in the chain would most likely be a getting a clock with jitter an order of magnitude or greater than the first device. I once had to run a setup like that where I had to clock 4 devices each to the previous one. The signal from the last device would not pass back to the first one without noise/dropouts likely from serial clock phase error.

At least with loop sync the I/O is paralleled except at the loop master which is providing the clock.
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