I made a project using the Max132 and I have the evaluation board, that
is very well assembled, vaste ground sections, even a underlay extra board
will all ground.  Everything worked fine.  My project used it at 20 bits, what
was took long nights to make it work nicely, but we never got it breathing
pizza or pickles... :)  Truth by truth, it really takes more than 500 bytes in
assembler code just to control the miserable, and several tracks on the board.

As the project changed in the middle, we moved to the AD7713, and then
also we stated that ADC's with large bit count are just code eaters.  Again,
in the middle of the project, with several problems, AD released the AD7714,
that fixed few problems and increased few features.

Still almost need to go to college to learn how to operate those guys.
Right now I just take a brief look at the "internal registers" manual pages, if

it takes 15 pages or more  in pdf  format, ai ai ai... it is a sign that things

would *not be easy* as expected to write the code in just 30 minutes.

Right now we have the pcb's ready to the 7713 and a buying the 7714.
They are not compatible pin to pin. arghh.

Wagner.



Marc wrote:

> > Max132 is a 18 bits ADC from Maxim, it is somehow nice to use
> > and quite stable, but as a rule, pcb layout and wide and low resistance
> > ground conductors are very important to consider when dealing above
> > 12 or 14 bits.
>
> I made software for a board with MAX132 and AVR. My experience was that the
> MAX132 might become flaky when breathing (!) on it (no I didn't eat old
> pizza :-). Although zero calibration was used to compensate for temperature
> before reading each any every sample, the values went up through the roof!
> When breathing on it extensivly the values even crossed the 21 bit border,
> and the MAX132 then did stop completly (did not signal EOC anymore).
>
> After about 10 seconds the results settled back into the valid range, and
> within 60-90 seconds they returned completly to their normal precision.
>
> I didn't design the hardware for that project, but everything looked fine,
> and we tried several boards/max132s, and checked for flux, moisture and
> heat problems. With no success. It all appeared to be the MAX132 itself.
>
> Maxim did say they do not know of that problem, but did not want to send
> an evaluation board for us to try or reproduce the problem themselves
> (at least they said they don't).
>
> So until now it's not sure if it's really a MAX132 problem. Maybe
> one of you PICLIST readers has a working MAX132 board on your desk
> right now to try it and confirm/deny?
>
> Until then I'll not use that particular device in my own designs (but
> others from Maxim which I am very satisfied with).