differential scsi termination

Tak Asami asami at dt.wdc.com
Mon Feb 5 19:05:02 PST 1996


* From the SCSI Reflector, posted by:
* Tak Asami <asami at dt.wdc.com>
*
> * From the SCSI Reflector, posted by:
> * "James Leahy" <jleahy at pyramid.com>
> *
> 
> I've been told that the termination for differential ultra-scsi is
> being reduced to 90 ohms from 120 ohms. Could someone from the X3t10
> committee comment on this?

Not to my knowledge.  Fast-20 is about to becomd a standard, and the
latest draft revision, as far as I know, is 6, and it has been stable
for several month.
This document still specifies Termpwr-330ohm-150ohm-330ohm-gnd for
differential impedance of about 120ohm.  This is identical to what is
on SPI (which is already a standard).

Could that "rumor" come from spi-2 low voltage differential work?
LVD tereminator's differential impedance is somewhere around 90ohm.
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                           Tak Asami
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