AD7739 Analog Devices, AD7739 Datasheet - Page 11

• Manufacturer Part Number: AD7739
• Description: 8-Channel, 4 kHz, 24-Bit Sigma-Delta A/D Converter
• Manufacturer: Analog Devices

Specifications of AD7739

• Resolution (bits): 24bit
• # Chan: 8
• Sample Rate: 3.05MSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni,SE-Bip,SE-Uni
• Ain Range: Bip 0.625,Bip 1.25,Bip 2.5V,Uni 0.625,Uni 1.25,Uni 2.5V
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

CHOPPING DISABLED
The second mode, in which the AD7739 is configured with
chopping disabled (CHOP = 0), provides faster conversion time
while 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 7. Typical Output RMS Noise in µV vs. Conversion Time and Input Range with Chopping Disabled
FW
Table 8. Typical Effective Resolution in Bits vs. Conversion Time and Input Range with Chopping Disabled
FW
Table 9. Typical Peak-to-Peak Resolution in Bits vs. Conversion Time and Input Range with Chopping Disabled
FW
127
127
127
92
35
16
12
11
92
35
16
12
11
92
35
16
12
11
3
3
3
Conversion
Conversion
Conversion
Register
Register
Register
0x5C
0x0C
0x5C
0x0C
0x0B
0x5C
0x0C
0x0B
0x23
0x10
0x0B
0x03
0x7F
0x23
0x10
0x03
0x7F
0x23
0x10
0x03
0x7F
Time
Time
Time
Conversion
Conversion
Conversion
1358
1358
1358
Time
Time
Time
993
399
201
160
149
993
399
201
160
149
993
399
201
160
149
(µs)
(µs)
(µs)
66
66
66
Output Data
Output Data
Output Data
15133
15133
15133
1007
2504
4963
6257
6693
1007
2504
4963
6257
6693
1007
2504
4963
6257
6693
737
Rate
737
Rate
737
Rate
(Hz)
(Hz)
(Hz)
Frequency
Frequency
Frequency
29000
29000
29000
2500
5400
7250
7900
2500
5400
7250
7900
2500
5400
7250
7900
Rev. 0 | Page 11 of 32
–3 dB
–3 dB
–3 dB
675
950
675
950
675
950
(Hz)
(Hz)
(Hz)
±2.5 V
±2.5 V
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.
21.0
20.7
20.1
19.4
18.9
18.8
14.6
18.2
17.8
17.2
16.6
16.1
16.0
11.7
±2.5 V, +2.5 V
11.4
200
2.4
3.0
4.5
6.9
9.6
Input Range / Peak-to-Peak Resolution (Bits)
Input Range / Effective Resolution (Bits)
+2.5 V
+2.5 V
20.0
19.7
19.1
18.4
17.9
17.8
13.6
17.2
16.8
16.2
15.6
15.1
15.0
10.7
Input Range / RMS Noise (µV)
±1.25 V
±1.25 V
20.6
20.4
19.8
19.2
18.8
18.5
14.7
17.8
17.6
17.0
16.4
16.0
15.7
12.0
±1.25 V, +1.25 V, ±0.625 V, +0.625 V
+1.25 V ±0.625 V +0.625 V
+1.25 V ±0.625 V +0.625 V
19.6
19.4
18.8
18.2
17.8
17.5
13.7
16.8
16.6
16.0
15.4
15.0
14.7
11.0
1.5
1.8
2.7
4.1
5.3
6.9
90
19.6
19.4
18.8
18.2
17.8
17.5
13.7
16.8
16.6
16.0
15.4
15.0
14.7
11.0
AD7739
18.6
18.4
17.8
17.2
16.8
16.5
12.7
15.8
15.6
15.0
14.4
14.0
13.7
10.0