Re: gEDA-user: series terminators

[Evan Lavelle <eml-geda@xxxxxxxxxxx>]

After all that, I forgot to mention the line length. Rule of thumb: if 
the first reflection gets back to the driver before the driver has 
finished transitioning, then you probably don't have a problem, and you 
don't need termination. In your case, that's 12", or about 1ns. So, if 
your drivers have edge rates of ~1ns or faster, you may have a problem. 
Another rule of thumb: modern CMOS circuits which are designed to go 
'fast-ish' (quick clock->out, so high slew rate drivers) probably have a 
slew rate in the range of 1.5 - 2.5ns. I don't know what chips you're 
using, but you probably don't have a problem.

Evan


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