Datasheet
ADS1291
ADS1292
ADS1292R
www.ti.com
SBAS502B –DECEMBER 2011–REVISED SEPTEMBER 2012
ELECTRICAL CHARACTERISTICS
Minimum and maximum specifications apply from –40°C to +85°C. Typical specifications are at +25°C. All specifications are
at DVDD = 1.8 V, AVDD – AVSS = 3 V
(1)
, V
REF
= 2.42 V, external f
CLK
= 512 kHz, data rate = 500 SPS, C
FILTER
= 4.7 nF
(2)
,
and gain = 6, unless otherwise noted.
ADS1291, ADS1292, ADS1292R
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
ANALOG INPUTS
Full-scale differential input voltage
±V
REF
/ gain V
(AINP – AINN)
See the Input Common-Mode Range
Input common-mode range subsection of the PGA Settings and Input
Range section
Input capacitance 20 pF
T
A
= +25°C, input = 1.5 V ±200 pA
Input bias current (PGA chop = 8 kHz) T
A
= –40°C to +85°C, input = 1.5 V ±1 nA
Chop rates other than 8 kHz See Pace Detect section
No pull-up or pull-down current source 1000 MΩ
Current source lead-off detection (nA),
500 MΩ
DC input impedance AVSS + 0.3 V < AIN < AVDD – 0.3 V
Current source lead-off detection (µA),
100 MΩ
AVSS + 0.6 V < AIN < AVDD – 0.6 V
PGA PERFORMANCE
Gain settings 1, 2, 3, 4, 6, 8, 12
With a 4.7-nF capacitor on PGA output
Bandwidth (see PGA Settings and Input Range section 8.5 kHz
for details)
ADC PERFORMANCE
Resolution 24 Bits
Data rate f
CLK
= 512 kHz 125 8000 SPS
CHANNEL PERFORMANCE (DC Performance)
Gain = 6
(3)
, 10 seconds of data 8 μV
PP
Gain = 6, 256 points, 0.5 seconds of data 8 11 μV
PP
Input-referred noise
Gain settings other than 6,
See Noise Measurements section
data rates other than 500 SPS
Integral nonlinearity Full-scale with gain = 6, best fit 2 ppm
Offset error ±100 μV
Offset error drift 2 μV/°C
Offset error with calibration 15 μV
Gain error Excluding voltage reference error ±0.1 ±0.2 % of FS
Gain drift Excluding voltage reference drift 2 ppm/°C
Gain match between channels 0.2 % of FS
CHANNEL PERFORMANCE (AC performance)
CMRR Common-mode rejection ratio f
CM
= 50 Hz and 60 Hz
(4)
–105 –120 dB
PSRR Power-supply rejection ratio f
PS
= 50 Hz and 60 Hz 90 dB
Crosstalk f
IN
= 50 Hz and 60 Hz –120 dB
SNR Signal-to-noise ratio f
IN
= 10 Hz input, gain = 6 107 dB
10 Hz, –0.5 dBFs, C
FILTER
= 4.7nF –104 dB
100 Hz, –0.5 dBFs, C
FILTER
= 4.7nF –95 dB
THD Total harmonic distortion
ADS1292R channel 1, 10 Hz, –0.5 dBFS,
–82 dB
C
FILTER
= 47 nF
(1) Performance is applicable for 5-V operation as well. Production testing for limits is performed at 3 V.
(2) C
FILTER
is the capacitor accross the PGA outputs; see the PGA Settings and Input Range section for details.
(3) Noise data measured in a 10-second interval. Test not performed in production. Input-referred noise is calculated with input shorted
(without electrode resistance) over a 10-second interval.
(4) CMRR is measured with a common-mode signal of AVSS + 0.3 V to AVDD – 0.3 V. The values indicated are the minimum of the two
channels.
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