Maxim and Analog Devices.

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.

Maxim just released another 16 bits ADC, take a look at their web
site.  But if you need 16 bits, you need to go for higher bits resolution
microchips, since the last one or two bits from *almost every* chip
is instable or requires lots of details to get it nicelly.  So to get 16
bits
in a good shape, go for 18 or more bits ADC.

AD7714 (the upgrade from AD7713) from Analog Devices, it is
a nice $14.00 unit, that goes up to 22bits, but in 16 it is very clean and
easy to operate, well, requires some chip protocol preset.  It has 4
channels, lots of calibration techniques and very stable. There is some
frequency notch filters you can program.  I am using it for 20 bits right
now and it is a quite solution.

Mostly all ADC bigger than 12 bits are quite programmable and require
considerable programming.  You need to have a week reading the pdf files
to understand everything in details, since sometimes it is tricky.
There is *no* 16 bits ADC low cost with a simple select and read pins.

The two above have all you need, zero and full scale programmable, so it
automatically removes all the both sides offsets.  The AD7713 has a
programmable gain amplifier so you can scale the input voltage internally,
and the possibility to convert the 4 bipolar into more unipolar inputs.

For a reverse situation, 16 bits serial DAC 8 pins (Linear Tech LTC1595),
from $25 to $60, and compare with the analog signal to read, so your
software will do a *binary search* or "watch dog style search" until  the
analog comparing goes close to one bit resolution error, than the value
post
at the DAC will be equivalent to the reading value.  It requires some
time for the reading, but it is quite fast solution for instrumentation,
and you
still have the DAC to generate analog output if required.

Wagner Lipnharski
UST Research Inc
http://www.ustr.net

Jim Dolson wrote:

> Does anyone have a suggestion for a basic 16 bit A/D converter?  I need
> to do samples just once a second, so speed is not terribly important.
> Good availability and ease of use is more important that speed.
>
> Thanks,
>
> Jim
> jdolson@iserv.net