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To help the audience in this round of comments, I would like to
highlight an open issue from the St. Louis meeting.
Regarding the I/O specification of the Sync_Err and the PMA_SI output
signals, draft 3.1 and previous drafts has this defined as LVCMOS
Here are some things to note as you think about this issue.The mandatory Sync_Err signal is defined to be LVTTL
1) SFI-4 (OIF document which XSBI is leveraged from) has their mandatory
Sync_Err defined as LVPECL.
2) LVCMOS outputs would be compatible w/ LVPECL inputs.This doesn't work. In fact for low speed signalling, this is the
3) The specific LVCMOS standard to use is not defined in current draft.Quick research on the ANSI site led to EIA/JESD8-B Interface Standard
4) The intent of having XSBI as an optional clause in the standard is toAs defined by JESD8-B
allow implentors to use existing components built from the OIF
It does not necessary mean we copy OIF exactly.
There are three options to choose from as we head into Portland and
1) Leave definition as is, i.e. LVCMOS. Allows newer technologies. Still
need to define what LVCMOS levels to use.
1) Revert to LVPECL as in OIF. This will insure compatibility w/delete this idea
are out built upon SFI-4 specs. There is still the question of
specs should be referenced.
A good second option. Since the signals are optional, is there a
2) Leave the I/O type undefined. Problem here is that IEEE historically
done this for a physical instantiation description, i.e. I/O/s
have been defined.
-- Tim Warland P.Eng. Hardware Design Engineer Broadband Products High Performance Optical Component Solutions Nortel Networks (613)765-6634