Datasheet

–2–
REV. 0
AD7731–SPECIFICATIONS
Parameter B Version
1
Units Conditions/Comments
STATIC PERFORMANCE (CHP = 0)
No Missing Codes
2
24 Bits min SKIP = 0
3
Output Noise and Update Rates
2
See Tables I and II
Integral Nonlinearity 15 ppm of FSR max
Offset Error
2
See Note 4 Offset Error and Offset Drift Refer to Both
Offset Drift vs. Temperature
2
0.5 µV/°C typ Input Range = 20 mV, 40 mV, 80 mV, 160 mV
1/2/5 µV/°C typ Input Range = 320 mV/640 mV/1.28 V
Offset Drift vs. Time
5
2.5 µV/1000 Hr
Positive Full-Scale Error
2, 6
See Note 4
Positive Full-Scale Drift vs. Temp
2, 7, 8
0.6 µV/°C typ Input Range = 20 mV, 40 mV, 80 mV, 160 mV
1.5/3/6 µV/°C typ Input Range = 320 mV/640 mV/1.28 V
Positive Full-Scale Drift vs. Time
5
3 µV/1000 Hr
Gain Error
2, 9
See Note 4
Gain Drift vs. Temperature
2, 7, 10
2 ppm/°C typ
Gain Drift vs. Time
5
10 ppm/1000 Hr
Bipolar Negative Full-Scale Error
2
See Note 4
Negative Full-Scale Drift vs. Temp
2, 7
1 µV/°C typ
Power Supply Rejection
11
90 dB typ Input Range = 20 mV
Power Supply Rejection
11
60 dB typ Input Range = 1.28 V
Common-Mode Rejection (CMR)
11
On AIN 95 dB typ At DC. Input Range = 20 mV
On AIN 85 dB typ At DC. Input Range = 1.28 V
On REF IN 120 dB typ
Analog Input DC Bias Current
2
60 nA max
Analog Input DC Bias Current Drift
2
150 pA/°C typ
Analog Input DC Offset Current
2
30 nA max
Analog Input DC Offset Current Drift
2
100 pA/°C typ
STATIC PERFORMANCE (CHP = 1)
2
No Missing Codes 24 Bits min
Output Noise and Update Rates See Tables III and IV
Integral Nonlinearity 15 ppm of FSR max
Offset Error See Note 4 Offset Error and Offset Drift Refer to Both
Offset Drift vs. Temperature 5 nV/°C typ Unipolar Offset and Bipolar Zero Errors
Offset Drift vs. Time
5
25 nV/1000 Hr typ
Positive Full-Scale Error
6
See Note 4
Positive Full-Scale Drift vs. Temp
7, 8
2 ppm of FS/°C max
Positive Full-Scale Drift vs. Time
5
10 ppm of FS/1000 Hr
Gain Error
9
See Note 4
Gain Drift vs. Temperature
7, 10
2 ppm/°C max
Gain Drift vs. Time
5
10 ppm/1000 Hr
Bipolar Negative Full-Scale Error See Note 4
Negative Full-Scale Drift vs. Temp 2 ppm of FS/°C max
Power Supply Rejection
11
110 dB typ Input Range = 20 mV
Power Supply Rejection
11
85 dB typ Input Range = 1.28 V
Common-Mode Rejection (CMR)
11
On AIN 110 dB typ At DC. Input Range = 20 mV
On AIN 85 dB typ At DC. Input Range = 1.28 V
On REF IN 120 dB typ
Analog Input DC Bias Current 50 nA max
Analog Input DC Bias Current Drift 100 pA/°C typ
Analog Input DC Offset Current 10 nA max
Analog Input DC Offset Current Drift 50 pA/°C typ
ANALOG INPUTS/REFERENCE INPUTS
Normal Mode 50 Hz/60 Hz Rejection
2
88 dB min 50 Hz/60 Hz ±1 Hz. SKIP = 0
Common-Mode 50 Hz/60 Hz Rejection
2
120 dB min 50 Hz/60 Hz ±1 Hz. SKIP = 0
Analog Inputs
Differential Input Voltage Ranges
12
Assuming 2.5 V or 5 V Reference with HIREF
Bit Set Appropriately
0 to +20 or ±20 mV nom RN2, RN1, RN0 of Mode Register = 0, 0, 1
0 to +40 or ±40 mV nom RN2, RN1, RN0 of Mode Register = 0, 1, 0
0 to +80 or ±80 mV nom RN2, RN1, RN0 of Mode Register = 0, 1, 1
0 to +160 or ±160 mV nom RN2, RN1, RN0 of Mode Register = 1, 0, 0
0 to +320 or ±320 mV nom RN2, RN1, RN0 of Mode Register = 1, 0, 1
0 to +640 or ±640 mV nom RN2, RN1, RN0 of Mode Register = 1, 1, 0
0 to +1.28 or ±1.28 V nom RN2, RN1, RN0 of Mode Register = 1, 1, 1
(AV
DD
= +5 V, DV
DD
= +3 V or +5 V; REF IN(+) = +2.5 V; REF IN(–) = AGND; AGND =
DGND = 0 V; f
CLK IN
= 4.9152 MHz. All specifications T
MIN
to T
MAX
unless otherwise noted.)
REV. A