mdd@lzaz.UUCP (Mark Duffy) (01/20/86)
I am trying to select a driver IC that will meet RS-232C and V.28
to 19.2 kbps, SYNC and ASYNC. None of the commonly used parts seem
acceptable!
The most popular devices on the market seem to be the 1488, 9636,
and 75150 types:
The 1488s don't have a fast enough slew rate to meet the transition
time requirement beyond about 9600 bps ASYNC and 4800 SYNC (fully
loaded outputs). In addition, they require diodes on the power supply
leads to protect against fault conditions. Does anyone know how many
devices may share a set of diodes before the protection is compromised?
The 9636 types have good operational characteristics, but have a
rather disagreeable tendency to burn violently under fault conditions
(e.g. outputs shorted). It seems that it may be possible to protect
these devices with diodes on the power supply, but with 12V +-5%
supplies, these diodes would put the supply voltage to the chips out
of spec.
I know relatively little about the 75150s, except that they seem
to be the least popular in equipment I have seen. Both the 75150 and
9636 data sheets specify that only one output may be shorted at once.
Has anyone out there had trouble with their devices burning up?
With output transitions being too slow? Can anyone recommend any
other devices? Does anyone actually meet V.28 at 19.2 kbps? Please
post replies to net.dcom; or respond by e-mail or collect telephone
and I will summarize to the net.
Any help would be greatly appreciated. Thanks!
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Mark Duffy (201) 576-7903 ...ihnp4!lzaz!mdd