REV. A
–3–
AD7709
SPECIFICATIONS1
(VDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V, REFIN(+) = 2.5 V; REFIN(–) = GND; GND = 0 V; XTAL1/XTAL2 =
32.768 kHz Crystal; all specifications TMIN to TMAX, unless otherwise noted.)
Parameter
AD7709A, AD7709B
Unit
Test Conditions
ADC CHANNEL SPECIFICATION
Output Update Rate
5.4
Hz min
0.732 ms Increments
105
Hz max
ADC CHANNEL
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 II to V
Integral Nonlinearity
2
±30
ppm of FSR max
Typically 2 ppm FSR
REFIN
GAIN
=
21 024
.
Offset Error
±3
mV typ
Offset Error Drift vs. Temperature
±10
nV/
∞C typ
Full-Scale Error
3
±0.75
LSB typ
B Grade, VDD = 4 V
±0.2
% of FS typ
A Grade
Gain Drift vs. Temperature
±0.5
ppm/
∞C typ
Power Supply Rejection (PSR)
85
dB typ
Input Range =
±2.56 V
100 dB typ on
±20 mV Range
ANALOG INPUTS
Differential Input Voltage Ranges
±
1 024
.
REFIN
GAIN
V nom
REFIN = REFIN(+) – REFIN(–)
GAIN = 1 to 128
ADC Range Matching
±2
mV typ
Input Voltage = 19 mV on All Ranges
Absolute AIN1–AIN4 Voltage Limits
2
GND + 100 mV
V min
VDD – 100 mV
V max
AIN1–AIN4 Analog Input Current
DC Input Current
2
±1
nA max
DC Input Current Drift
±5
pA /
∞C typ
Absolute AINCOM Voltage Limits
2
GND – 30 mV
V min
VDD + 30 mV
V max
AINCOM Analog Input Current
Pseudo-Differential Mode of Operation
DC Input Current
±125
nA/V typ
Input Current Varies with Input Range
DC Input Current Drift
±2
pA/V/
∞C typ
Normal-Mode Rejection
2, 4
@ 50 Hz
100
dB min
50 Hz
± 1Hz, 16.65 Hz Update Rate, SF = 82
@ 60 Hz
100
dB min
60 Hz
± 1 Hz, 20 Hz Update Rate, SF = 68
Common-Mode Rejection
@ DC
100
dB typ
Input Range =
±2.56 V, AIN = 1 V
110 dB typ on
±20 mV Range
@ 50 Hz
2
100
dB min
50 Hz
± 1 Hz, Range = ±2.56 V, AIN = 1 V
@ 60 Hz
2
100
dB min
60 Hz
± 1 Hz, Range = ±2.56 V, AIN = 1 V
REFERENCE INPUTS
(REFIN1 and REFIN2)
REFIN Voltage
2.5
V nom
REFIN = REFIN(+) – REFIN(–)
REFIN Voltage Range
2
1V min
VDD
V max
Absolute REFIN Voltage Limits
2
GND – 30 mV
V min
VDD + 30 mV
V max
Average Reference Input Current
0.5
mA/V typ
Average Reference Input Current Drift
±0.01
nA/V/
∞C typ
Normal-Mode Rejection
2, 4
@ 50 Hz
100
dB min
50 Hz
± 1 Hz, SF = 82
@ 60 Hz
100
dB min
60 Hz
± 1 Hz, SF = 68
Common-Mode Rejection
@ DC
110
dB typ
Input Range =
±2.56 V, AIN = 1 V
@ 50 Hz
110
dB typ
50 Hz
± 1 Hz, Range = 2.56 V, AIN = 1 V
@ 60 Hz
110
dB typ
60 Hz
± 1 Hz, Range = 2.56 V, AIN = 1 V
See Notes on page 5.