New LVD-SCSI constraints

Kevin Gingerich S=Kevin_Gingerich%S=Gingerich%G=Kevin%TI at
Thu Feb 1 06:58:00 PST 1996

* From the SCSI Reflector, posted by:
* Kevin Gingerich <S=Kevin_Gingerich%S=Gingerich%G=Kevin%TI at>

  To  SCSI Reflector   X400
>From  Kevin Gingerich  GING
/pn=scsi/mbx1=scsi at
Subj  New LVD-SCSI constraints
Here are the current set of system constraints I am using for the LVD-
SCSI specification. It reflects changes to reduce the bus common-mode
voltage range to 0.7 V to 1.8 V. This was accomplished by a reduction in
the allowable ground potential difference to 0.355 V from 0.5 V and the
termination common-mode resistance maximum from 300 ohms to 150 ohms. I
also added the minimum common-mode impedance of 100 ohms for the
terminators. (Note that these changes will affect all of the test
circuits and conditions I presented in Denver.)
Differential Bus Parameter    Minimum        Maximum
iin                                 -20.0E-6  20.0E-6
negation current multiplier              0.5     1.05
nodes                                      2       16
vbias (open circuit)                     0.1     0.13
z0                                       110      135
zload                                     85      135
zt                                       110      115
Common-mode Bus Parameter     Minimum        Maximum
icmd                                 -500E-6   500E-6
iin                                 -20.0E-6  20.0E-6
nodes                                      2       16
vgnd                                  -0.355    0.355
vt(oc)                                 1.125    1.375
z0                                        55     67.5
zcmt                                     100      150

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