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AD7747
Rev. 0 | Page 4 of 28
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
75
dB
50 Hz ± 1%, conversion time = 122.1 ms
50
dB
60 Hz ± 1%, conversion time = 122.1 ms
95
dB
VIN = 1 V
INTERNAL VOLTAGE REFERENCE
Voltage
1.169
1.17
1.171
V
TA = 25°C
Drift vs. Temperature
5
ppm/°C
EXTERNAL VOLTAGE REFERENCE INPUT
0.1
2.5
VDD
V
GND 0.03
VDD + 0.03
V
Average REFIN Input Current
400
nA/V
Average REFIN Input Current Drift
±50
pA/V/°C
Common-Mode Rejection
80
dB
SERIAL INTERFACE LOGIC INPUTS (SCL, SDA)
VIH Input High Voltage
2.1
V
VIL Input Low Voltage
0.8
V
Hysteresis
150
mV
Input Leakage Current (SCL)
±0.1
±1
μA
OPEN-DRAIN OUTPUT (SDA)
VOL Output Low Voltage
0.4
V
ISINK = 6.0 mA
IOH Output High Leakage Current
0.1
1
μA
VOUT = VDD
LOGIC OUTPUT (RDY)
VOL Output Low Voltage
0.4
V
ISINK = 1.6 mA, VDD = 5 V
VOH Output High Voltage
4.0
V
ISOURCE = 200 μA, VDD = 5 V
VOL Output Low Voltage
0.4
V
ISINK = 100 μA, VDD = 3 V
VOH Output High Voltage
VDD 0.6
V
ISOURCE = 100 μA, VDD = 3 V
POWER REQUIREMENTS
VDD-to-GND Voltage
4.75
5.25
V
VDD = 5 V, nominal
2.7
3.6
V
VDD = 3.3 V, nominal
IDD Current
850
μA
Digital inputs equal to VDD or GND
750
μA
VDD = 5 V
700
μA
VDD = 3.3 V
IDD Current Power-Down Mode
0.5
2
μA
Digital inputs equal to VDD or GND
1 Capacitance units: 1 pF = 1012 F; 1 fF = 1015 F; 1 aF = 1018 F. Full scale (FS) = 8.192 pF; full-scale range (FSR) = ±8.192 pF.
2 Specification is not production tested, but is supported by characterization data at initial product release.
3 Factory calibrated. The absolute error includes factory gain calibration error, integral nonlinearity error, and offset error after system offset calibration, all at 25°C.
At different temperatures, compensation for gain drift over temperature is required.
4 The capacitive input offset can be eliminated using a system offset calibration. The accuracy of the system offset calibration is limited by the offset calibration register
LSB size (32 aF) or by converter + system p-p noise during the system capacitive offset calibration, whichever is greater. To minimize the effect of the converter +
system noise, longer conversion times should be used for system capacitive offset calibration. The system capacitance offset calibration range is ±1 pF; the larger
offset can be removed using CAPDACs.
5 Specification is not production tested, but guaranteed by design.
6 The gain error is factory calibrated at 25°C. At different temperatures, compensation for gain drift over temperature is required.
7 The VTCHOP bit in the VT SETUP register must be set to 1 for the specified temperature sensor and voltage input performance.
8 Using an external temperature sensing diode 2N3906, with nonideality factor nf = 1.008, connected as in Figure 37, with total serial resistance <100 Ω. 9 Full-scale error applies to both positive and negative full scale.