Data Sheet
AD7798/AD7799
AD7799
Table 7 shows the AD7799 output rms noise for some update
rates and gain settings. The numbers given are for the bipolar
input range with a 2.5 V reference. These numbers are typical
and are generated with a differential input voltage of 0 V. Table 8
shows the effective resolution, and the output peak-to-peak
resolution is given in parentheses. Note that the effective
resolution is calculated using the rms noise, whereas the
peak-to-peak resolution is based on peak-to-peak noise. The
peak-to-peak resolution represents the resolution for which
there is no code flicker. These numbers are typical and are
rounded to the nearest LSB.
Table 7. Output RMS Noise (µV) vs. Gain and Output Update Rate for the AD7799 Using a 2.5 V Reference
Update Rate
4.17 Hz
8.33 Hz
16.7 Hz
33.2 Hz
62 Hz
123 Hz
242 Hz
470 Hz
Gain of 1
Gain of 2
Gain of 4
0.185
0.269
0.433
0.647
0.952
1.356
3.797
3.132
Gain of 8
0.097
0.165
0.258
0.364
0.586
0.785
2.054
1.773
Gain of 16
0.075
0.108
0.176
0.24
0.361
0.521
1.027
1.107
Gain of 32
0.035
0.048
0.085
0.118
0.178
0.265
0.476
0.5
Gain of 64
Gain of 128
0.027
0.040
0.065
0.094
0.134
0.192
0.308
0.374
0.64
1.04
1.55
2.3
2.95
4.89
11.76
11.33
0.6
0.027
0.037
0.065
0.097
0.133
0.192
0.326
0.413
0.96
1.45
2.13
2.85
4.74
9.5
9.44
Table 8. Typical Resolution (Bits) vs. Gain and Output Update Rate for the AD7799 Using a 2.5 V Reference
Update Rate
4.17 Hz
8.33 Hz
16.7 Hz
33.3 Hz
62 Hz
123 Hz
242 Hz
470 Hz
Gain of 1
23 (20.5)
22 (19.5)
21.5 (19)
21 (18.5)
20.5 (18)
20 (17.5)
18.5 (16)
18.5 (16)
Gain of 2
22 (19.5)
21.5 (19)
20.5 (18)
20 (17.5)
19.5 (17)
19 (16.5)
18 (15.5)
18 (15.5)
Gain of 4
22.5 (20)
22 (19.5)
21.5 (19)
21 (18.5)
20.5 (18)
20 (17.5)
18.5 (16)
18.5 (16)
Gain of 8
22.5 (20)
22 (19.5)
21 (18.5)
20.5 (18)
20 (17.5)
19.5 (17)
18 (15.5)
18.5 (16)
Gain of 16
22 (19.5)
21.5 (19)
21 (18.5)
20.5 (18)
19.5 (17)
19 (16.5)
18 (15.5)
18 (15.5)
Gain of 32
22 (19.5)
21.5 (19)
21 (18.5)
20.5 (18)
19.5 (17)
19 (16.5)
18.5 (16)
18.5 (16)
Gain of 64
21.5 (19)
21 (18.5)
20 (17.5)
19.5 (17)
19 (16.5)
18.5 (16)
18 (15.5)
17.5 (15)
Gain of 128
20.5 (18)
20 (17.5)
19 (16.5)
18.5 (16)
18 (15.5)
17.5 (15)
17 (14.5)
16.5 (14)
Rev. B | Page 11 of 28
ROCHESTER [ Rochester Electronics ]
