Data Translation DT9820 Series, User Manual

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Principles of Operation
11
2
2
2
2
2
2
2
2
2
For each A/D subsystem, choose the gain that has the smallest
effective range that includes the signal you want to measure. For
example, if you are using a DT9822 and the range of your analog
input signal is ±1.05 V, specify a range of
−
2.
5
V to +2.5 V for the
module and use a gain of 2 for the channel; the effective input range
for this channel is then ±1.2 5V, which provides the best sampling
accuracy for that channel.
You can either specify the gain as part of the single-value operation,
or you can specify the gain using an analog input gain list. Enter the
gain in the gain list if you want to clock A/D conversions.
Table 2: Effective Input Range
Gain
Unipolar Input
Range
Bipolar Input
Range
1 0 to 2.5 V
−
0.10 to 2.5 V ±2.5 V
2 0 to 1.25 V
−
0.10 to 1.25 V ±1.25 V
4 0 to 0.6250 V
−
0.10 to 0.6250 V ±0.6250 V
8 0 to 0.3125 V
−
0.10 V to 0.3125 V ±0.3125 V
16 0 to 0.15625 V
−
0.10 V to
0.15625 V
±0.15625 V
32 0 to 0.078125
−
0.10 V to
0.078125 V
±0.078125
64 0 to 0.0390625
−
0.10 V to
0.0390625 V
±0.0390625