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AD7747
Rev. 0 | Page 3 of 28
SPECIFICATIONS
VDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V; GND = 0 V; EXC = ±VDD × 3/8; 40°C to +125°C, unless otherwise noted.
Table 1.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
CAPACITIVE INPUT
Conversion Input Range
±8.192
Factory calibrated
Integral Nonlinearity (INL)
2±0.01
24
Bit
Conversion time ≥ 124 ms
Resolution, p-p
16.5
Bit
Conversion time 124 ms, see
Table 5Resolution Effective
19.1
Bit
Conversion time 124 ms, see
Table 5Output Noise, rms
11.0
aF/
√Hz
Conversion time 124 ms, see
Table 5±10
25°C, VDD = 5 V, after offset calibration
32
After system offset calibration,
System Offset Calibration Rang
e5±1
pF
Offset Deviation over Temperatur
e20.4
fF
0.02
0.11
25°C, VDD = 5 V
Gain Drift vs. Temperature
223
26
29
ppm of FS/°C
0.5
4
fF/V
72
dB
50 Hz ± 1%, conversion time 124 ms
60
dB
60 Hz ± 1%, conversion time 124 ms
CAPDAC
Full Range
17
21
pF
6-bit CAPDAC
Differential Nonlinearity (DNL)
0.3
LSB
26
ppm of FS/°C
EXCITATION
Frequency
16
kHz
AC Voltage Across Capacitance
±VDD × 3/8
V
To be configured via digital interface
Average DC Voltage Across Capacitance
VDD/2
V
VREF internal
Resolution
0.1
°C
±0.5
±2
°C
Internal temperature sensor
±2
°C
VREF internal or VREF = 2.5 V
Differential VIN Voltage Range
±VREF
V
GND 0.03
VDD + 0.03
V
Integral Nonlinearity (INL)
±3
±15
ppm of FS
24
Bit
Conversion time = 122.1 ms
Resolution, p-p
16
Bits
Conversion time = 62 ms,
Output Noise
3
μV rms
Conversion time = 62 ms,
Offset Error
±3
μV
Offset Drift vs. Temperature
15
nV/°C
0.025
0.1
% of FS
Full-Scale Drift vs. Temperature
5
ppm of FS/°C
Internal reference
0.5
ppm of FS/°C
External reference
Average VIN Input Current
300
nA/V
Analog VIN Input Current Drift
±50
pA/V/°C
Power Supply Rejection
80
dB
Internal reference, VIN = VREF/2
90
dB
External reference, VIN = VREF/2