Datasheet

AD7794/AD7795
Rev. D | Page 3 of 36
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
1
AD7794/AD7795 Unit Test Conditions/Comments
CHOP ENABLED
Output Update Rate 4.17 to 470 Hz nom Settling time = 2/output update rate
No Missing Codes
2
AD7794 24 Bits min f
ADC
≤ 242 Hz
AD7795 16 Bits min
Resolution See the RMS Noise and Resolution Specifications section
RMS Noise and Update Rates See the RMS Noise and Resolution Specifications section
Integral Nonlinearity ±15
ppm of FSR
max
Offset Error
3
±1 μV typ
Offset Error Drift vs. Temperature
4
±10 nV/°C typ
Full-Scale Error
3, 5
±10 μV typ
Gain Drift vs. Temperature
4
±1 ppm/°C typ Gain = 1 to 16, external reference
±3 ppm/°C typ Gain = 32 to 128, external reference
Power Supply Rejection 100 dB min AIN = 1 V/gain, gain ≥ 4, external reference
ANALOG INPUTS
Differential Input Voltage Ranges ±VREF/gain V nom
V
REF
= REFIN(+) − REFIN(−), or internal reference,
gain = 1 to 128
Absolute AIN Voltage Limits
2
Unbuffered Mode GND − 30 mV V min Gain = 1 or 2
AV
DD
+ 30 mV V max
Buffered Mode GND + 100 mV V min Gain = 1 or 2
AV
DD
− 100 mV V max
In-Amp Active GND + 300 mV V min Gain = 4 to 128
AV
DD
− 1.1 V max
Common-Mode Voltage, V
CM
0.5 V min VCM = (AIN(+) + AIN(−))/2, gain = 4 to 128
Analog Input Current
Buffered Mode or In-Amp
Active
Average Input Current
2
AD7794B/AD7795B ±1 nA max Gain = 1 or 2, update rate < 100 Hz
±250 pA max Gain = 4 to 128, update rate < 100 Hz
±1 nA max AIN6(+)/AIN6(−)
AD7794C ±3 nA max Gain = 1 or 2, update rate < 100 Hz
±2 nA max Gain = 4 to 128, update rate < 100 Hz
±3 nA max AIN6(+)/AIN6(−)
Average Input Current Drift ±2 pA/°C typ
Unbuffered Mode Gain = 1 or 2
Average Input Current ±400 nA/V typ Input current varies with input voltage
Average Input Current Drift ±50 pA/V/°C typ
Normal Mode Rejection
2, 6
Internal Clock
@ 50 Hz, 60 Hz 65 dB min 80 dB typ, 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010
@ 50 Hz 80 dB min 90 dB typ, 50 ± 1 Hz, FS[3:0] = 1001
@ 60 Hz 90 dB min 100 dB typ, 60 ± 1 Hz, FS[3:0] = 1000
External Clock
@ 50 Hz, 60 Hz 80 dB min 90 dB typ, 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010
@ 50 Hz 94 dB min 100 dB typ, 50 ± 1 Hz, FS[3:0] = 1001
@ 60 Hz 90 dB min 100 dB typ, 60 ± 1 Hz, FS[3:0] = 1000