Datasheet
REV. 0
–6–
AD7708/AD7718
AD7708 SPECIFICATIONS
1
(AV
DD
= 2.7 V to 3.6 V or 4.75 V to 5.25 V, DV
DD
= 2.7 V to 3.6 V or 4.75 V to 5.25 V,
REFIN(+) = 2.5 V; REFIN(–) = AGND; AGND = DGND = 0 V; XTAL1/XTAL2 = 32.768 kHz Crystal Input Buffers Enabled. All specifications T
MIN
to
T
MAX
unless otherwise noted.)
Parameter B Grade Unit Test Conditions
AD7708 (CHOP DISABLED)
Output Update Rate 16.06 Hz min CHOP = 1
1.365 kHz max
No Missing Codes
2
16 Bits min
Resolution 13 Bits p-p ±20 mV Range, SF Word = 69
16 Bits p-p ±2.56 V Range, SF Word = 69
Output Noise and Update Rates See Tables in ADC Description
Integral Nonlinearity ±15 ppm of FSR max 2ppm Typical
Offset Error
3
±0.65 LSB typ Following a Self-Calibration
Offset Error Drift vs. Temp
4
±200 nV/°C typ
Full-Scale Error
3
±0.75 LSB typ
Gain Drift vs. Temp
4
±0.5 ppm/°C typ
Negative Full-Scale Error ±0.003 % FSR 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
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 Bias Current Drift ±5 pA/°C typ
AINCOM Input Current NEGBUF = 0
DC Input Current
2
±125 nA/V typ ±2.56 V Range
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 100 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 100 dB typ 50 Hz ± 1 Hz, SF Word = 82
@ 60 Hz 100 dB typ 60 Hz ± 1 Hz, SF Word = 68
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 0.5 µA/V typ
Reference DC Input Current Drift ±0.1 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 100 dB typ Analog Input = 1 V. Input Range = ±2.56 V
@ 50 Hz 100 dB typ
@ 60 Hz 100 dB typ