16 Oct
2012
16 Oct
'12
1:02 p.m.
open collector drivers. What that means is that the
signal lines in the
bus are normally held at something like 3.4V (a logical "on") by
resistors at both ends of the bus that terminate the bus and form a
voltage divider. The chips are all TTL, so if you were to just directly
connect a TTL-level driver to the bus and assert a "high" logic level,
it would try to pull the bus to +5V and you would be in a world of
trouble. The open collector drivers don't ever do that, they can either
LVD devices that works with 3.3V as "high"? There is an entire line of
74's made in LVD/LVX flavor :o)