17 Jun
2013
17 Jun
'13
10:47 p.m.
On 06/17/2013 09:50 PM, Mouse wrote:
Let's not criticize the spec for the failings of
one particular
implementation. Unless you have some reason to think this is
unavoidable, that any implementation of the spec will necessarily be
that power-hungry...?
Well, it goes to my first point about +/-3-+/-15 volts into what?
Resistance, capacitance, what are limits? Where in the spec does it
say? Us 10 pF too little and 10 uF too much?
So the old devices had to be practical, meaning lots of current and
voltage into a loosely-specified load. I suspect that a MAX232 probably
wouldn't have enough oomph to drive some of the old 1960s gear.
As far as pin count--differential is only 2 pins; on single-ended
signals, you still need a return line for the signal line.
--Chuck