AD7190 datasheet(12/21 Pages) AD

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AD7190

Preliminary Technical Data

Rev.PrD 7/08 | Page 12

SINC3 FILTER

For a given update rate, the sinc3 filter has lower settling time

than the sinc3 filter. At low update rates, the rms noise is

comparable between the sinc3 filter and the sinc4 filter. So, the

user can optimize the settling time without compromising the

rms noise. At high update rates, the sinc4 filter is needed for

optimum performance of the AD7190.

CHOP DISABLED

Table 9 shows the rms noise of the AD7190 for some of the

update rates and gain settings with chop disabled. The

numbers given are for the bipolar input range with the

external 5 V reference. These numbers are typical and are

generated with a differential input voltage of 0 V. Table 10

shows the effective resolution while 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,

while the p-p resolution is calculated based on peak-to-peak

noise. The p-p resolution represents the resolution for which

there will be no code flicker. These numbers are typical and

are rounded to the nearest half-LSB.

Table 9. RMS Noise (nV) vs. Gain and Output Update Rate (continuous conversion mode) Using a 5 V Reference - Chop Disabled

Filter Word

(Decimal)

Update

Rate (Hz)

Gain of 1

Gain of 8

Gain of 16

Gain of 32

Gain of 64

Gain of 128

1023

4.7

177

26.5

13.22

10.52

8.7

7.68

640

7.5

200

16.12

13.13

10.97

10.02

480

276

20.48

15.42

12.82

10.74

606

36.92

29.68

25.66

300

1400

205

112

73.21

2400

57510

7000

3570

1770

896

464

4800

438100

54690

27340

14220

6890

3480

Table 10. Typical Resolution (Bits) vs. Gain and Output Update Rate (continuous conversion mode) Using a 5 V Reference - Chop

Disabled

Filter Word

(Decimal)

Update

Rate (Hz)

Gain of 1

Gain of 8

Gain of 16

Gain of 32

Gain of 64

Gain of 128

1023

4.7

24 (23)

24 (22)

24 (21.5)

23.5 (21)

640

7.5

24 (23)

24 (22.5)

24 (22)

24 (21.5)

23 (20.5)

480

24 (22.5)

24 (22)

24 (21.5)

23.5 (21)

23 (20.5)

24 (21.5)

23.5 (21)

23 (20.5)

22.5 (20)

21.5 (19)

300

23(20.5)

22.5 (20)

22 (19.5)

21 (18.5)

20.5 (18)

2400

17.5 (15)

4800

14.5 (12)

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