ELAN DIGITAL SYSTEMS LTD. AD121, User Manual

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Elan Digital Systems Ltd. 12 AD125 USER’S GUIDE
3.2 A to D OUTPUT FORMAT / GAIN SETTING
The AD125 produces 2’s complement 12 bit output codes when in
Bipolar mode and “true binary” 12 bit codes when in Unipolar
mode. Table 3.2-1 summarises the codes.
THEORETICAL AD125 OUTPUT CODE
INPUT LEVEL BIPOLAR UNIPOLAR
(F.S. = FULL SCALE)
BINARY HEX BINARY HEX
F.S. 011111111111 7FF 111111111111 FFF
F.S. - 1LSB 011111111110 7FE 111111111110 FFE
.... .... .... .... ....
0 + 2LSB 000000000010 002 000000000010 002
0 +1LSB 000000000001 001 000000000001 001
0 000000000000 000 000000000000 000
0 - 1LSB 111111111111 FFF
0 - 2LSB 111111111110 FFE
.... .... ....
-F.S. + 1LSB 100000000001 801
-F.S. 100000000000 800
Remember that the size of the LSB step changes depending on the
input range selected and whether you are operating in Unipolar or
Bipolar mode.