EVAL-AD7747EBZ Analog Devices Inc, EVAL-AD7747EBZ Datasheet - Page 11

• Manufacturer Part Number: EVAL-AD7747EBZ
• Description: 24-Bit Capacitance-to-Digital Converter Eval. Board
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7747EBZ

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Capacitance-to-Digital Converter
• Kit Application Type: Data Converter
• Silicon Core Number: AD7747
• Sensor Type: Touch, Capacitive
• Interface: I²C
• Voltage - Supply: 2.7 V ~ 5.25 V
• Embedded: No
• Utilized Ic / Part: AD7747
• Kit Contents: Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensitivity: -
• Sensing Range: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

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
pins connected only to the evaluation board (no external
capacitors).
Table 5. Typical Capacitive Input Noise and Resolution vs. Conversion Time (Bold line represents default setting)
Conversion
Time (ms)
22.0
23.9
40.0
76.0
124.0
154.0
184.0
219.3
Table 6. Typical Voltage Input Noise and Resolution vs. Conversion Time, Internal Voltage Reference
Conversion
Time (ms)
20.1
32.1
62.1
122.1
Table 7. Typical Voltage Input Noise and Resolution vs. Conversion Time, External 2.5 V Voltage Reference
Conversion
Time (ms)
20.1
32.1
62.1
122.1
Output Data
Rate (Hz)
45.5
41.9
25.0
13.2
8.1
6.5
5.4
4.6
Output Data
Rate (Hz)
49.8
31.2
16.1
8.2
Output Data
Rate (Hz)
49.8
31.2
16.1
8.2
DD
× 3/8, and with all CIN and SHLD
−3 dB Frequency
(Hz)
43.6
39.5
21.8
10.9
6.9
5.3
4.4
4.0
−3 dB Frequency
(Hz)
26.4
15.9
8.0
4.0
−3 dB Frequency
(Hz)
26.4
15.9
8.0
4.0
RMS Noise
(aF/√Hz)
28.8
23.2
11.1
11.2
11.0
10.4
10.0
9.0
RMS Noise
(μV)
11.4
7.1
4.0
3.0
RMS Noise
(μV)
14.9
6.3
3.3
2.1
Rev. 0 | Page 11 of 28
RMS
Noise (aF)
190
146
52
37
29
24
21
18
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.
P-P Noise
(μV)
62
42
28
20
P-P Noise
(μV)
95
42
22
15
P-P
Noise (aF)
821
725
411
262
174
173
141
126
Effective Resolution
(Bits)
16.4
16.8
18.3
18.7
19.1
19.3
19.6
19.9
Effective Resolution
(Bits)
17.6
18.3
19.1
19.5
Effective Resolution
(Bits)
18.3
19.6
20.5
21.1
P-P Resolution
(Bits)
14.3
14.5
15.3
15.9
16.5
16.5
16.8
17.0
P-P Resolution
(Bits)
15.2
15.7
16.3
16.8
P-P Resolution
(Bits)
15.6
16.8
17.7
18.3
AD7747