EVAL-AD7997CB Analog Devices Inc, EVAL-AD7997CB Datasheet - Page 17
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EVAL-AD7997CB
Manufacturer Part Number
EVAL-AD7997CB
Description
BOARD EVALUATION FOR AD7997
Manufacturer
Analog Devices Inc
Datasheet
1.AD7997BRUZ-1.pdf
(32 pages)
Specifications of EVAL-AD7997CB
Number Of Adc's
1
Number Of Bits
10
Sampling Rate (per Second)
188k
Data Interface
Serial
Inputs Per Adc
8 Single Ended
Input Range
0 ~ 5.5 V
Power (typ) @ Conditions
7.7mW @ 188kSPS, 5.5 V
Voltage Supply Source
Single
Operating Temperature
-40°C ~ 85°C
Utilized Ic / Part
AD7997
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
For ac applications, removing high frequency components from
the analog input signal is recommended, by using an RC band-
pass filter on the relevant analog input pin. In applications where
harmonic distortion and signal-to-noise ratio are critical, the
analog input should be driven from a low impedance source.
Large source impedances significantly affect the ac performance
of the ADC. This may necessitate the use of an input buffer
amplifier. The choice of the op amp is a function of the particular
application.
When no amplifier is used to drive the analog input, the source
impedance should be limited to low values. The maximum source
impedance depends on the amount of total harmonic distortion
(THD) that can be tolerated. THD increases as the source imped-
ance increases, and performance degrades. Figure 23 shows the
THD vs. the analog input signal frequency when using supply
voltages of 3 V ± 10% and 5 V ± 10%. Figure 24 shows the THD
vs. the analog input signal frequency for different source
impedances.
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–100
–60
–100
–40
–50
–70
–80
–90
–60
–40
–50
–70
–80
–90
10
10
Figure 23. THD vs. Analog Input Frequency for Various
Figure 24. THD vs. Analog Input Frequency for Various
Source Impedances for V
V
DD
= 2.7V
Supply Voltages, F
INPUT FREQUENCY (kHz)
INPUT FREQUENCY (kHz)
V
V
DD
100
DD
100
S
DD
= 5V
= 136 kSPS, Mode 1
= 4.5V
R
R
= 5 V, 136 kSPS, Mode 1
IN
V
IN
DD
R
= 1000 Ω
= 100 Ω
IN
= 3V
= 10 Ω
AD7997/AD7998
V
DD
V
DD
= 3.3V
= 5.5V
R
IN
V
= 50 Ω
DD
= 5V
1000
1000