REV. 0
–7–
AD7708/AD7718
Parameter B Grade Unit Test Conditions
AD7708 (CHOP ENABLED)
Output Update Rate 5.4 Hz min CHOP = 1
105 Hz max 0.732 ms Increments
No Missing Codes
2
16 Bits min 20 Hz Update Rate
Resolution 13 Bits p-p ±20 mV Range, 20 Hz Update Rate
16 Bits p-p ±2.56 V Range, 20 Hz Update Rate
Output Noise and Update Rates See Tables in
ADC Description
Integral Nonlinearity ±15 ppm of FSR max 2 ppm Typical
Offset Error
3
±3 µV typ Calibration is Accurate to ±0.5 LSB
Offset Error Drift vs. Temp
4
10 nV/°C typ
Full-Scale Error
3
±0.75 LSB typ Includes Positive and Negative ERRORS
Gain Drift vs. Temp
4
±0.5 ppm/°C typ
ANALOG INPUTS
Differential Input Full-Scale Voltage ±1.024 × REFIN/GAIN V nom REFIN Refers to Both REFIN1 and
REFIN2. REFIN = REFIN(+) REFIN(–)
GAIN = 1 to 128
Range Matching ±2 µV typ Analog Input = 18 mV
Absolute AIN Voltage Limits AGND + 100 mV V min AIN1–AIN10 and AINCOM with
AV
DD
– 100 mV V max NEGBUF = 1
Absolute AINCOM Voltage Limits AGND – 30 mV V min NEGBUF = 0
AV
DD
+ 30 mV V max
Analog Input Current AIN1–AIN10 and AINCOM with
NEGBUF = 1
DC Input Current
2
±1 nA max
DC Input Current Drift ±5 pA/°C typ
AINCOM Input Current NEGBUF = 0
DC Input Current
2
±125 nA/V typ
DC Bias Current Drift ±2 pA/V/°C typ
Normal-Mode Rejection
2
@ 50 Hz 100 dB min 50 Hz ± 1 Hz, SF Word = 82
@ 60 Hz 94 dB min 60 Hz ± 1 Hz, SF Word = 68
Common-Mode Rejection
@ DC 90 dB min 100 dB typ, Analog Input = 1 V,
Input Range = ±2.56 V
110 dB typ on ±20 mV Range
@ 50 Hz
2
100 dB min 50 Hz ± 1 Hz, 20 Hz Update Rate
@ 60 Hz
2
100 dB min 60 Hz ± 1 Hz, 20 Hz Update Rate
REFERENCE INPUTS (REFIN1 AND REFIN2)
REFIN(+) to REFIN(–) Voltage 2.5 V nom REFIN Refers to Both REFIN1 and
REFIN2
REFIN(+) to REFIN(–) Range
2
1V min
AV
DD
V max
REFIN Common-Mode Range AGND – 30 mV V min
AV
DD
+ 30 mV V max
Reference DC Input Current
2
±0.5 µA/V typ
Reference DC Input Current Drift ±0.01 nA/V/°C typ
Normal-Mode Rejection
2
@ 50 Hz 100 dB min 50 Hz ± 1 Hz, SF Word = 82
@ 60 Hz 100 dB min 60 Hz ± 1 Hz, SF Word = 68
Common-Mode Rejection Input Range = ±2.56 V
@ DC 110 dB typ Analog Input = 1 V
@ 50 Hz 110 dB typ 50 Hz ± 1 Hz, 20 Hz Update Rate
@ 60 Hz 110 dB typ 60 Hz ± 1 Hz, 20 Hz Update Rate
LOGIC INPUTS
5
All Inputs Except SCLK and XTAL1
2
V
INL
, Input Low Voltage 0.8 V max DV
DD
= 5 V
0.4 V max DV
DD
= 3 V
V
INH
, Input High Voltage 2.0 V min DV
DD
= 3 V or 5 V