Datasheet

AD7796/AD7797
Rev. A | Page 3 of 24
SPECIFICATIONS
AV
DD
= 2.7 V to 5.25 V, DV
DD
= 2.7 V to 5.25 V, GND = 0 V, all specifications T
MIN
to T
MAX
, unless otherwise noted.
Table 1.
Parameter AD7796B/AD7797B
1
Unit Test Conditions/Comments
ADC CHANNEL
Output Update Rate 4.17 to 123 Hz nom
No Missing Codes
2
24 Bits min AD7797 only
16 Bits min AD7796 only
Resolution See Table 7 and Table 8
RMS Noise and Update Rates See Table 6
Integral Nonlinearity ±10 ppm of FSR typ
Offset Error
3, 4
±1 μV typ
Offset Error Drift vs. Temperature
4
±10 nV/°C typ
Full-Scale Error
3, 4, 5
±10 μV typ
Gain Drift vs. Temperature
4
±3 ppm/°C typ
Power Supply Rejection 90 dB min AIN = 1 V/128
ANALOG INPUTS
Differential Input Voltage Ranges ±V
REF
/128 V nom V
REF
= REFIN(+) – REFIN(–)
Absolute AIN Voltage Limits
2
GND + 300 mV V min
AV
DD
− 1.1 V max
Common-Mode Voltage, V
CM
0.5 V min V
CM
= (AIN(+) + AIN(–))/2
Analog Input Current
Average Input Current
2
±250 pA max Update rate < 100 Hz
Average Input Current Drift ±2 pA/°C typ
Normal Mode Rejection
2
Internal Clock
@ 50 Hz, 60 Hz 65 dB min 80 dB typ, 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010
6
@ 50 Hz 80 dB min 90 dB typ, 50 ± 1 Hz, FS[3:0] = 1001
6
@ 60 Hz 90 dB min 100 dB typ, 60 ± 1 Hz, FS[3:0] = 1000
6
External Clock
@ 50 Hz, 60 Hz 80 dB min 90 dB typ, 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010
6
@ 50 Hz 94 dB min 100 dB typ, 50 ± 1 Hz, FS[3:0] = 1001
6
@ 60 Hz 90 dB min 100 dB typ, 60 ± 1 Hz, FS[3:0] = 1000
6
Common-Mode Rejection
@ DC 90 dB min AIN = 7.81 mV
@ 50 Hz, 60 Hz
2
90 dB min 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010
6
@ 50 Hz, 60 Hz
2
90 dB min
50 ± 1 Hz (FS[3:0] = 1001
6
), 60 ± 1 Hz,
FS[3:0] = 1000
6
REFERENCE
External REFIN Voltage 2.5 V nom REFIN = REFIN(+) – REFIN(–)
Reference Voltage Range
2
0.1 V min
AV
DD
V max
Absolute REFIN Voltage Limits
2
GND − 30 mV V min
AV
DD
+ 30 mV V max
Average Reference Input Current 400 nA/V typ
Average Reference Input Current Drift ±0.03 nA/V/°C typ
Normal Mode Rejection Same as for analog inputs
Common-Mode Rejection 100 dB typ
TEMPERATURE SENSOR
Accuracy ±2 °C typ Applies if user calibrates the temperature sensor
Sensitivity 0.81 mV/°C typ