AD7739 Analog Devices, AD7739 Datasheet - Page 28

• 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

AD7739
FREQUENCY RESPONSE
The sigma-delta modulator runs at ½ the MCLK frequency,
which is effectively the sampling frequency. Therefore, the
modulator Nyquist frequency is ¼ of the MCLK.
If chopping is enabled, the input signal is resampled by
chopping. Therefore, the overall frequency response features
notches close to the frequency of 1/channel conversion time.
–100
–120
–100
–120
–20
–40
–60
–80
–20
–40
–60
–80
Figure 27. Typical ADC Frequency Response, Chopping Disabled
Figure 26. Typical ADC Frequency Response, Chopping Enabled
0
0
0
0
CHOP = 1
CHOP = 0
(INPUT FREQUENCY × CONVERSION TIME)
(INPUT FREQUENCY × CONVERSION TIME)
NORMALIZED INPUT FREQUENCY
NORMALIZED INPUT FREQUENCY
Rev. 0 | Page 28 of 32
1
1
The typical ADC frequency response plots are given in
Figure 26 and Figure 27. The plots are normalized to 1/channel
conversion time.
Note that these figures apply to each channel separately and are
based on individual channel conversion time. The signal is
effectively resampled once more in the multiplexer by switching
between enabled analog inputs.
10
10
Preliminary Technical Data
100
100
03742-0-026
03742-0-027