AD7191

Rev. A | Page 13 of 20

RMS NOISE AND RESOLUTION SPECIFICATIONS

Table 5 shows the rms noise of the AD7191 for the four output

data rates and four gains. The numbers given are for an

external 5 V reference. These numbers are typical and are

generated with a differential input voltage of 0 V. Table 6

shows the effective resolution; the output peak-to-peak (p-p)

resolution is listed in brackets. It is important to note that the

effective resolution is calculated using the rms noise, whereas

the p-p resolution is calculated based on peak-to-peak noise.

The p-p resolution represents the resolution for which there is

no code flicker. These numbers are typical and are rounded to

the nearest half-LSB.

The effective resolution (ENOB) is defined as

The noise-free bits or p-p resolution is defined as

Table 5. RMS Noise (nV) vs. Gain and Output Data Rate Using a 5 V Reference

ODR2, ODR1

Output Data Rate (Hz)

Settling Time (ms)

Gain of 1

Gain of 8

Gain of 64

Gain of 128

11

10

400

490

85

17

15

10

50

80

2000

260

46

34

01

60

66.7

2100

273

48

38

00

120

33.3

2400

315

64

51

Table 6. Typical Resolution (Bits) vs. Gain and Output Update Rate Using a 5 V Reference

ODR2, ODR1

Output Data Rate (Hz)

Settling Time (ms)

Gain of 1

Gain of 8

Gain of 64

Gain of 128

11

10

400

24 (21.5)

23.5 (21)

23 (20.5)

22 (19.5)

10

50

80

22 (19.5)

22 (19.5)

21.5 (19)

20.5 (18)

01

60

66.7

22 (19.5)

22 (19.5)

21.5 (19)

20.5 (18)

00

120

33.3

22 (19.5)

21.5 (19)

21 (18.5)

20 (17.5)