[802.3ae] XSBI - LVCMOS I/O's
Hello all,
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
outputs. During the last mtg some thought this inappropriate while
others thought it quite proper. In earlier mtgs many months back,
the XSBI working group decided it was best to put an I/O type for these
signals and selected LVCMOS as the I/O of choice.
Here are some things to note as you think about this issue.
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.
3) The specific LVCMOS standard to use is not defined in current draft.
4) The intent of having XSBI as an optional clause in the standard is to
allow implentors to use existing components built from the OIF
effort.
It does not necessary mean we copy OIF exactly.
There are three options to choose from as we head into Portland and
draft 3.2.
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/
components that
are out built upon SFI-4 specs. There is still the question of
what
LVPECL
specs should be referenced.
2) Leave the I/O type undefined. Problem here is that IEEE historically
has not
done this for a physical instantiation description, i.e. I/O/s
have been defined.
--
Justin Chang
Quake Technologies, Inc
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