8 Feb
2006
8 Feb
'06
7:23 a.m.
So to shed more light on the Am26S10 receiver
threshold I decided to do
a little lab work, since I have both DS8641 and Am26S10 physical devices
available. The Vbus vs Vrcvr input/output plots can be seen here:
http://www.ak6dn.com/stuff/26S10vs8641.jpg
Nice :-)!
As can be seen in the plot, the classic DS8641 has a
very well defined
receiver switching threshold in the 1.35-1.5V range. The Am26S10
receiver threshold is in the 1.85-2.25V range, about 0.5-0.75V higher
(not unexpected, this is what the data sheet indicates).
So the Am26S10 parts are somewhere in between the DS8641 at 1.7V and the
older DS8838/DEC380 parts at 2.5V. They should work on a reasonably
sized UNIBUS system (not pushing loads and/or lengths) but may not be
optimal for some configurations (Appendix B of the UNIBUS
Troubleshooting Guide on bitsavers has some good background info on the
threshold issue).
Agreed. Among the off-the-shelf interface parts, I couldn't find anything
better. (Wish the 75als057 had higher voltage tolerances!)
Vince