The AD4858 have several analog input ranges available, from Softspan 1 to 15, described in Table 1. Depending on the expected input voltage swing, both its amplitude and being unipolar/bipolar, user must select the most appropriate Softspan range on each channel.
Table 1
|
|
|
Ideal Range (VREFBUF = 4.096 V) |
|
||
|
SoftSpan |
Differential Input Range |
Negative Full Scale |
Zero Scale |
Positive Full Scale |
LSB (µV) |
|
|
Bipolar (Two’s Complement) |
|
|
|
|
|
15 |
±10x(VREFBUF/1.024) |
40 |
0 |
40 |
76.294 |
|
13 |
±6.25x(VREFBUF/1.024) |
-25 |
0 |
25 |
47.684 |
|
11 |
±5x(VREFBUF/1.024) |
-20 |
0 |
20 |
38.147 |
|
9 |
±3.125x(VREFBUF/1.024) |
-12.5 |
0 |
12.5 |
23.842 |
|
7 |
±2.5x(VREFBUF/1.024) |
-10 |
0 |
10 |
19.073 |
|
5 |
±1.5625x(VREFBUF/1.024) |
-6.25 |
0 |
6.25 |
11.921 |
|
3 |
±1.25x(VREFBUF/1.024) |
-5 |
0 |
5 |
9.537 |
|
1 |
±0.625x(VREFBUF/1.024) |
-2.5 |
0 |
2.5 |
4.768 |
|
|
Unipolar (Straight Binary) |
|
|
|
|
|
14 |
|
|
0 |
40 |
38.147 |
|
12 |
|
|
0 |
25 |
23.842 |
|
10 |
|
|
0 |
20 |
19.073 |
|
8 |
|
|
0 |
12.5 |
11.921 |
|
6 |
|
|
0 |
10 |
9.537 |
|
4 |
|
|
0 |
6.25 |
5.960 |
|
2 |
|
|
0 |
5 |
4.768 |
|
0 |
|
|
0 |
2.5 |
2.384 |