is the MCF CLKOUT signal used _by_ the NB modules or just passed
through to the header? MOD5270 particularly, MOD5282 as an aside.
Do the NB modules use CLKOUT?
Re: Do the NB modules use CLKOUT?
The System Clock is used by the SDRAM. Putting long wires and or bad reflections on this line can
cause SDRAM problems. If you are doing a design that needs this signal, keep the wire short and consider
a zero delay PLL clock buffer with a bit of termination on the input.
Story is the same for 5270,5282 and 5234.
The 5272 has less internal buffering and is EVEN more sensitive to this issue.
cause SDRAM problems. If you are doing a design that needs this signal, keep the wire short and consider
a zero delay PLL clock buffer with a bit of termination on the input.
Story is the same for 5270,5282 and 5234.
The 5272 has less internal buffering and is EVEN more sensitive to this issue.
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DBrunermer
- Posts: 67
- Joined: Thu Apr 21, 2011 7:06 am
- Location: Pittsburgh, PA
Re: Do the NB modules use CLKOUT?
I know this post was kind of old, but do you have a recommendation for the zero-delay buffer? I did a quick search at digikey, and there seem to be thousands of them. I'm really not sure what I'm looking for, exactly. The development board schematic doesn't seem to call one out, so maybe I'm also wondering how necessary it is. Does it become more important with higher clocks? E.g., if I switch to the new MOD54415, will it be even more critical?
Thanks, Dan B. (MOD 5272 - for now)
Thanks, Dan B. (MOD 5272 - for now)