EVAL-AD7767EDZ Analog Devices Inc, EVAL-AD7767EDZ Datasheet - Page 21
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EVAL-AD7767EDZ
Manufacturer Part Number
EVAL-AD7767EDZ
Description
BOARD EVAL AD7767 128KSPS 108DB
Manufacturer
Analog Devices Inc
Specifications of EVAL-AD7767EDZ
Number Of Adc's
1
Number Of Bits
24
Sampling Rate (per Second)
128k
Data Interface
Serial
Inputs Per Adc
1 Differential
Input Range
±VREF
Power (typ) @ Conditions
15mW @ 128kSPS
Voltage Supply Source
Analog and Digital
Operating Temperature
-40°C ~ 105°C
Utilized Ic / Part
AD7767
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
ANTIALIASING
The AD7767/AD7767-1/AD7767-2 sample the analog input
at a maximum rate of 1.024 MHz. The on-board digital filter
provides up to 100 dB attenuation for any possible aliasing
frequency in the range from the beginning of the filter stop
band (0.547 × ODR) to where the image of the digital filter pass
band occurs. This occurs at MCLK minus the filter stop band
(MCLK − 0.547 × ODR), as shown in Figure 42.
Table 9 shows the attenuation achieved by various orders of
front-end antialias filters prior to the signal entering the AD7767/
AD7767-1/AD7767-2 at the image of the digital filter stop band,
which is 1.024 MHz − 0.547 × ODR.
Table 9. Antialias Filter Order,
Attenuation at at First Image Point
Model
AD7767
AD7767-1
AD7767-2
The
customers that require extra antialias protection. These devices
sample the signal internally at a rate of 20 MHz to achieve up to
a maximum of 156 kHz or 312 kHz output data rate. This
means that the first alias point of these devices when run at the
maximum speeds is 19.921 MHz and 19.843 MHz, respectively.
POWER DISSIPATION
The AD7767/AD7767-1/AD7767-2 offer exceptional perform-
ance at ultralow power. Figure 43, Figure 44, and Figure 45
show how the current consumption of the AD7767/AD7767-1/
AD7767-2 scales with the MCLK frequency applied to the device.
Both the digital and analog currents scale as the MCLK frequency
is reduced. The actual throughput equals the MCLK frequency
BAND OF INTEREST
AD7764
Figure 42. AD7767/AD7767-1/AD7767 Spectrum
and
Filter Order
First
Second
Third
First
Second
Third
First
Second
Third
ANTIALIAS PROTECTION
DIGITAL FILTER 100dB
AD7765
∑-Δ devices are available to
f
Attenuation at
1.024 MHz – 0.547 × ODR
27 dB
50 dB
70 dB
33 dB
62 dB
89 dB
38 dB
74 dB
110 dB
MCLK
FIRST IMAGE POINT
– (0.547 × ODR)
IMAGE AT
DIGITAL FILTER
f
MCLK
f
MCLK
Rev. C | Page 21 of 24
applied divided by the decimation rate employed by the device
in use. For instance, operating the AD7767 device with an MCLK
of 800 kHz results in an output data rate of 100 kHz due to the
decimate-by-8 filtering.
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
2.5
2.0
1.5
1.0
0.5
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
0
0
0
0
Figure 44. AD7767-1 Current vs. MCLK Frequency
Figure 45. AD7767-2 Current vs. MCLK Frequency
Figure 43. AD7767 Current vs. MCLK Frequency
100k
100k
100k
200k
200k
200k
300k
300k
300k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
400k
400k
400k
500k
500k
500k
AI
600k
AI
600k
600k
I
I
I
REF
REF
REF
DD
DD
700k
700k
700k
DI
DI
DD
DD
800k
800k
800k
DI
DD
900k
900k
900k
AI
AD7767
DD
1000k
1000k
1000k