AD7734

Rev. 0 | Page 11 of 32

Chopping Disabled

The second mode, in which the AD7734 is configured with

chopping disabled (CHOP = 0), provides faster conversion time

while still maintaining high resolution. Table 7 to Table 9 show

the –3 dB frequencies and typical performance versus the

channel conversion time and equivalent output data rate,

respectively. Table 7 shows the typical output rms noise. Table 8

shows the typical effective resolution based on the rms noise.

Table 9 shows the typical output peak-to-peak resolution,

representing values for which there will be no code flicker

within a 6-sigma limit. The peak-to-peak resolutions are not

calculated based on rms noise but on peak-to-peak noise.

These typical numbers are generated from 4096 data samples

acquired in continuous conversion mode with an analog input

voltage set to 0 V and MCLK = 6.144 MHz. The conversion

time is selected via the channel conversion time register.

Table 7. Typical Output RMS Noise in µV vs. Conversion Time and Input Range with Chopping Disabled

FW

Conversion Time

Register

Conversion Time

(µs)

Output Data Rate

(Hz)

–3 dB Frequency

(Hz)

RMS Noise

(µV)

127

7Fh

1357

737

670

13.2

92

5Ch

992

1008

920

15.5

44

2Ch

492

2032

1850

22.7

35

23h

398

2511

2290

26.3

16

10h

200

4991

2500

39.0

8

08h

117

8545

7780

57.0

3

03h

65

15398

14000

132

Table 8. Typical Effective Resolution in Bits vs. Conversion Time and Input Range with Chopping Disabled

Input Range/Effective Resolution (Bits)

FW

Conversion Time

Register

Conversion Time

(µs)

Output Data Rate

(Hz)

–3 dB Frequency

(Hz)

±10 V

0 V to +10 V

±5 V

0 V to +5 V

127

7Fh

1357

737

670

20.5

19.5

19.5

18.5

92

5Ch

992

1008

920

20.3

19.3

19.3

18.3

44

2Ch

492

2032

1850

19.7

18.7

18.7

17.7

35

23h

398

2511

2290

19.5

18.5

18.5

17.5

16

10h

200

4991

2500

19.0

18.0

18.0

17.0

8

08h

117

8545

7780

18.4

17.4

17.4

16.4

3

03h

65

15398

14000

17.2

16.2

16.2

15.2

Table 9. Typical Peak-to-Peak Resolution in Bits vs. Conversion Time and Input Range with Chopping Disabled

Input Range/Peak-to-Peak Resolution (Bits)

FW

Conversion Time

Register

Conversion Time

(µs)

Output Data Rate

(Hz)

–3 dB Frequency

(Hz)

±10 V

0 V to +10 V

±5 V

0 V to +5 V

127

7Fh

1357

737

670

17.6

16.6

16.6

15.6

92

5Ch

992

1008

920

17.4

16.4

16.4

15.4

44

2Ch

492

2032

1850

16.8

15.8

15.8

14.8

35

23h

398

2511

2290

16.6

15.6

15.6

14.6

16

10h

200

4991

2500

16.1

15.1

15.1

14.1

8

08h

117

8545

7780

15.5

14.5

14.5

13.5

3

03h

65

15398

14000

14.3

13.3

13.3

12.3