>it's anything like CMOS digital logic levels=>0-1.5 & 3.5-5.

Bill,

Check the "Electrical Characteristics" for any chip.  Note that it is
possible for each chip to differ.

As a rule, 15% Vdd and below is "0" on all chips.

For 12-bit parts, 35% and above is "1".

For 14-bit parts, 85% and above is "1".

That's just a basic rule, and it doesn't always apply.

Andy


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                     Andy Kunz - Montana Design
          Go fast, turn right, and keep the wet side down!
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