Spec issue on MSE leakage current in SPI-3

Bill Galloway BillG at breatech.com
Fri Apr 30 09:48:52 PDT 1999


* From the T10 Reflector (t10 at symbios.com), posted by:
* "Bill Galloway" <BillG at breatech.com>
*
Dan,

Maybe I am missing something here.... I still do not understand why you
are worried about a legal terminator (active or passive). What voltage
were you going to clamp at?  Until I understand why you are worried
about the terminators I would say that the exposure to passively negated
legacy devices is zero.

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at breatech.com

-----Original Message-----
From: owner-t10 at Symbios.COM [mailto:owner-t10 at Symbios.COM]On Behalf Of
Daniel_F_Smith at notes.seagate.com
Sent: Friday, April 30, 1999 10:48 AM
To: t10 at Symbios.COM
Subject: RE: Spec issue on MSE leakage current in SPI-3


* From the T10 Reflector (t10 at symbios.com), posted by:
* Daniel_F_Smith at notes.seagate.com
*
Okay, 55 ohms. I forgot about 2 terminators on the bus.  That makes
passive
negation capable of 100mA if an active terminator goes astray. And yes,
it
is an issue with terminators as well as drivers.  I would think that
most
drivers turn off their current sourcing as they approach passive
negation
levels to save power and minimize ringing.  But you are right, if a
driver
actively negates, strongly, we're looking at a lot of potential current.
The real question is: can the bus survive this type of activity without
loss of data?  I don't have any data on this, does anyone else have
experience that they can share?  Let's try to refrain from throwing
rocks
and see if we can prove this either way.

Bill:  What is our exposure to passively negated, legacy devices, today?
Would many of these end up on a multimode bus?

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