AD7608 Analog Devices, AD7608 Datasheet - Page 27

• Manufacturer Part Number: AD7608
• Description: 8-Channel DAS with 18-Bit, Bipolar, Simultaneous Sampling ADC
• Manufacturer: Analog Devices

Specifications of AD7608

• Resolution (bits): 18bit
• # Chan: 8
• Sample Rate: 200kSPS
• Interface: Par,Ser,SPI
• Analog Input Type: Diff-Bip
• Ain Range: Bip 10V,Bip 5.0V
• Adc Architecture: SAR
• Pkg Type: QFP

Data Sheet
Figure 46 to Figure 52 illustrates the effect of oversampling on
the code spread in a dc histogram plot. As the oversample rate
is increased, the spread of codes is reduced. (In Figure 46 to
Figure 52, AV
with OS ratio.)
1600
1400
1200
1000
2000
1800
1600
1400
1200
1000
2500
2000
1500
1000
800
600
400
200
800
600
400
200
500
0
0
0
–9 –8 –7 –6 –5 –4 –3 –2 –1 0
–8 –7 –6 –5 –4 –3 –2 –1
Figure 47. Histogram Of Codes—OS × 2 (14 Codes)
Figure 46. Histogram of Codes—No OS (18 Codes)
Figure 48. Histogram of Codes—OS × 4 (11 Codes)
3 3 35
–5
NO OVERSAMPLING
0
OVERSAMPLING BY 2
OVERSAMPLING BY 4
4
CC
1
40
= V
–4
15
82
DRIVE
–3
199
188
54
411
208
–2
684
= 5 V and the sampling rate was scaled
708
538
1001
1551
–1
1065
1170
CODE
CODE
CODE
1524
1377
2224
0
1208
1759
1 2 3 4 5 6 7 8 9
0
1913
852
1
1397
1
588
1072
902
2
328
2
146
498
427
3
3
66
165
4
64
21 5 0
4
57
5
14
5
9
6
Rev. A | Page 27 of 32
3500
3000
2500
2000
1500
1000
4500
4000
3500
3000
2500
2000
1500
1000
6000
5000
4000
3000
2000
1000
500
500
0
0
0
Figure 50. Histogram of Codes—OS × 16 (6 Codes)
Figure 51. Histogram of Codes—OS × 32 (5 Codes)
OVERSAMPLING BY 32
Figure 49. Histogram of Codes—OS × 8 (9 Codes)
–4
OVERSAMPLING BY 8
4
69
–2
11
–2
–3
78
1081
–1
648
–2
1301
–1
2176
–1
3947
0
CODE
CODE
CODE
3027
5403
0
0
2703
1756
1
OVERSAMPLING BY 16
1
1460
457
1
2
385
2
44
3
AD7608
17
2
3
7
2
4