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AD7747ARUZ-REEL7

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P29
AD7747
Rev. 0 | Page 9 of 28
150
–150
01k
05469-010
PARALLEL RESISTANCE (MΩ)
CAP ERROR (fF)
10 100
100
50
0
–50
–100
Figure 10. Capacitance Input Error vs. Parallel Resistance;
CIN(+) to GND = 8 pF, V
DD
= 5 V
0
–1000
0 200
05469-058
CIN TO SHLD RESISTANCE (kΩ)
CAP ERROR (fF)
–100
–200
–300
–400
–500
–600
–700
–800
–900
25 50 75 100 125 150 175
Figure 11. Capacitance Input Error vs. Resistance Between CIN1(+) and SHLD;
CIN(+) to GND = 8 pF, V
DD
= 5 V
100
–1000
0.091
05469-059
CIN TO SHLD RESISTANCE (MΩ)
CAP ERROR (fF)
–100
0
–200
–300
–400
–500
–600
–700
–800
–900
0.27 0.48 0.96 5 25 100
Figure 12. Capacitance Input Error vs. Resistance Between CIN(+) and SHLD;
CIN(+) to GND = 25 pF, V
DD
= 5 V
1.0
–1.0
0.01
100
05469-066
SHLD TO GND RESISTANCE (MΩ)
CAP ERROR (pF)
0.1 1.0 10.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
Figure 13. Capacitance Input Error vs. Resistance Between SHLD and GND;
CIN(+) to GND = 8 pF; V
DD
= 5 V
10
–100
1
100
05469-067
SERIAL RESISTANCE (kΩ)
CAP ERROR (fF)
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
25 pF
8 pF
Figure 14. Capacitance Input Error vs. Serial Resistance;
CIN(+) to GND = 8 pF and 25pF, V
DD
= 5 V
0.2
–0.6
2.5 5.5
05469-062
VDD (V)
CAP ERROR (fF)
0
–0.2
–0.4
3.0 3.5 4.0 4.5 5.0
Figure 15. Capacitance Input Power Supply Rejection (PSR);
CIN(+) to GND = 8 pF
AD7747
Rev. 0 | Page 10 of 28
200
–200
064
05469-050
CAPDAC CODE
CAPDAC DNL (fF)
150
100
50
0
–50
–100
–150
8 162432404856
Figure 16. CAPDAC Differential Nonlinearity (DNL)
2.0
–2.0
–50
150
05469-034
TEMPERATURE (°C)
ERROR (°C)
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–25 0 25 50 75 100 125
Figure 17. Internal Temperature Sensor Error vs. Temperature
1.0
–3.0
–50
150
05469-035
TEMPERATURE (°C)
ERROR (°C)
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–25 0 25 50 75 100 125
Figure 18. External Temperature Sensor Error vs. Temperature
0
–120
01k
05469-051
INPUT SIGNAL FREQUENCY (Hz)
GAIN (dB)
–20
–40
–60
–80
–100
100 200 300 400 500 600 700 800 900
Figure 19. Capacitive Channel Frequency Response;
Conversion Time = 22 ms
0
–120
0 200
05469-052
INPUT SIGNAL FREQUENCY (Hz)
GAIN (dB)
–20
–40
–60
–80
–100
25 50 75 100 125 150 175
Figure 20. Capacitive Channel Frequency Response;
Conversion Time = 124 ms
0
–120
0
400
05469-039
INPUT SIGNAL FREQUENCY (Hz)
GAIN (dB)
–20
–40
–60
–80
–100
50 100 150 200 250 300 350
Figure 21. Voltage Channel Frequency Response;
Conversion Time = 122.1 ms
AD7747
Rev. 0 | Page 11 of 28
OUTPUT NOISE AND RESOLUTION SPECIFICATIONS
The AD7747 resolution is limited by noise. The noise
performance varies with the selected conversion time.
Table 5 shows typical noise performance and resolution for the
capacitive channel. These numbers were generated from 1000
data samples acquired in continuous conversion mode, at an
excitation of 16 kHz, ±V
DD
× 3/8, and with all CIN and SHLD
pins connected only to the evaluation board (no external
capacitors).
Table 6 and Table 7 show typical noise performance and
resolution for the voltage channel. These numbers were
generated from 1000 data samples acquired in continuous
conversion mode with VIN pins shorted to ground.
RMS noise represents the standard deviation and p-p noise
represents the difference between minimum and maximum
results in the data. Effective resolution is calculated from rms
noise, and p-p resolution is calculated from p-p noise.
Table 5. Typical Capacitive Input Noise and Resolution vs. Conversion Time (Bold line represents default setting)
Conversion
Time (ms)
Output Data
Rate (Hz)
−3 dB Frequency
(Hz)
RMS Noise
(aF/√Hz)
RMS
Noise (aF)
P-P
Noise (aF)
Effective Resolution
(Bits)
P-P Resolution
(Bits)
22.0 45.5 43.6 28.8 190 821 16.4 14.3
23.9 41.9 39.5 23.2 146 725 16.8 14.5
40.0 25.0 21.8 11.1 52 411 18.3 15.3
76.0 13.2 10.9 11.2 37 262 18.7 15.9
124.0 8.1 6.9 11.0 29 174 19.1 16.5
154.0 6.5 5.3 10.4 24 173 19.3 16.5
184.0 5.4 4.4 10.0 21 141 19.6 16.8
219.3 4.6 4.0 9.0 18 126 19.9 17.0
Table 6. Typical Voltage Input Noise and Resolution vs. Conversion Time, Internal Voltage Reference
Conversion
Time (ms)
Output Data
Rate (Hz)
−3 dB Frequency
(Hz)
RMS Noise
(μV)
P-P Noise
(μV)
Effective Resolution
(Bits)
P-P Resolution
(Bits)
20.1 49.8 26.4 11.4 62 17.6 15.2
32.1 31.2 15.9 7.1 42 18.3 15.7
62.1 16.1 8.0 4.0 28 19.1 16.3
122.1 8.2 4.0 3.0 20 19.5 16.8
Table 7. Typical Voltage Input Noise and Resolution vs. Conversion Time, External 2.5 V Voltage Reference
Conversion
Time (ms)
Output Data
Rate (Hz)
−3 dB Frequency
(Hz)
RMS Noise
(μV)
P-P Noise
(μV)
Effective Resolution
(Bits)
P-P Resolution
(Bits)
20.1 49.8 26.4 14.9 95 18.3 15.6
32.1 31.2 15.9 6.3 42 19.6 16.8
62.1 16.1 8.0 3.3 22 20.5 17.7
122.1 8.2 4.0 2.1 15 21.1 18.3
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P29

AD7747ARUZ-REEL7

Mfr. #:
Buy AD7747ARUZ-REEL7
Manufacturer:
Analog Devices Inc.
Description:
Data Acquisition ADCs/DACs - Specialized 24Bit w/ Temp Sensr
Lifecycle:
New from this manufacturer.
Delivery:
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