Re: [SI-LIST] : How to identify SSO groups?

Andrew Ingraham (ingraham@wrksys.ENET.dec.com)
Tue, 23 Dec 97 06:41:49 EST

Start with your supplier (foundry) to see what their SSO rules are.
If they don't have a guideline for time of overlap, press them to
provide one. Probably more than 1ns, but less than 10ns. Use this
for starters.

(The first project I worked on where SSO was recognized, had a
vendor-supplied guideline of some 3-4ns for overlap time.)

Then do your own research using simulations and/or measurements.
As you note, it is load dependent. Long lines without parallel
(ECL style) terminations may reflect current transients back to the
source any number of nanoseconds after the driver has switched. I
do not see why it would be clock dependent. The amplitudes are not
all the same, so take that into consideration when you modify your
foundry's SSO guidelines.

Regards,
Andy Ingraham