SPI-2 driver test conditions

Kevin Gingerich S=Kevin_Gingerich%S=Gingerich%G=Kevin%TI at mcimail.com
Thu May 2 06:27:00 PDT 1996

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

  To  SCSI Reflector   X400
>From  Kevin Gingerich  GING
/pn=scsi/mbx1=scsi at symbios.com/ems=internet/admd=mci/c=us/
Subj  SPI-2 driver test conditions
Rich, when I use the test circuit values of ZL = 54.5 ohms, Zt = 54.5 ohms, pL
= 0, Vos = 114 mV, and with A = 0.85 in the equations, I get the following;
        Ia >= 0.47 In + 3.1 mA
and     In >= 0.47 Ia - 3.1 mA.
These functions would intersect at In = -2.1 mA and Ia = 2.1 mA. Obviously,
this in not a usable solution but it does satisify the -25% of the
opposite-state voltage on the first step. Since we want certain voltage levels
and polarities, you must further constrain Ia and In to a minimum and maximum
I am using the same set of assumptions you list in your message except, the
budget for attenuation is -1.4 dB (which turns out to be about 65 mV at the
minimum signaling levels).
Hope to see you in Ft. Lauderdale next week.

More information about the T10 mailing list