AD7608 Analog Devices, AD7608 Datasheet - Page 28

• 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

AD7608
When the oversampling mode is selected, this has the effect
of adding a digital filter function after the ADC. The different
oversampling rates and the CONVST x sampling frequency
produces different digital filter frequency profiles.
Figure 53 to Figure 58 show the digital filter frequency profiles
for oversampling by 2 to oversampling by 64. The combination
of the analog antialiasing filter and the oversampling digital
filter can be used to eliminate or reduce the complexity of the
design of the filter before the AD7608. The digital filtering
combines steep roll-off and linear phase response.
7000
6000
5000
4000
3000
2000
1000
–10
–20
–30
–40
–50
–60
–70
–80
–90
0
0
100
Figure 52. Histogram of Codes—OS × 64 (3 Codes)
OVERSAMPLING BY 64
465
–1
1k
Figure 53. Digital Filter OS × 2
FREQUENCY (Hz)
10k
CODE
6489
0
100k
1M
AV
V
T
±10V RANGE
OS BY 2
A
1238
DRIVE
CC
= 25°C
1
= 5V
= 5V
10M
Rev. A | Page 28 of 32
–100
–100
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
0
0
0
100
100
100
Figure 56. Digital Filter Response for OS × 16
Figure 54. Digital Filter Response for OS × 4
Figure 55. Digital Filter Response for OS × 8
1k
1k
1k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
10k
10k
10k
100k
100k
100k
Data Sheet
1M
1M
1M
AV
V
T
±10V RANGE
OS BY 4
AV
V
T
±10V RANGE
OS BY 8
AV
V
T
±10V RANGE
OS BY 16
A
A
DRIVE
DRIVE
A
DRIVE
CC
CC
CC
= 25°C
= 25°C
= 25°C
= 5V
= 5V
= 5V
= 5V
= 5V
= 5V
10M
10M
10M