Vitaliy wrote:
> Olin, you haven't read the datasheet yourself, have you? It says
> nothing about not using electrolytics.

We're talking about power supply "bypass" or "decoupling" caps.  Basic
electronics should be enough to assume that electrolytics are not suited for
this application unless the datasheet specifically says so, and I expect it
doesn't.  There is really no place left today for a 1uF electrolytic
capacitor.

> It says nothing about "low ESR", either. Any cap will do.

It may not say anything about ESR, but this gets to the level of obvious
unless the datasheet specifically says otherwise.  At some point they have
to rely on the person reading the datasheet to know at least a little about
electronics.  Keep in mind that even though a electrolytic would not be
violating the datasheet if taken literally, neither would a ceramic, and
there are plenty of good reasons to use a ceramic instead of a electrolytic
in this case.

> You guys seem to forget that these are level shifter circuits, not
> microcontrollers. The cap is there simply to keep the voltage on
> RS232 from going too far below 10V, for the duration of the bit.

It's a digital circuit that has switching transients and two or three charge
pumps.  Unless the datasheet explicity says otherwise, the assumption should
be that good power supply bypass is required.  The fact that they explicitly
call for 1uF should be a big clue that something there matters more than
usual.


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