Datasheet
ADS1294, ADS1294R
ADS1296, ADS1296R
ADS1298, ADS1298R
SBAS459I –JANUARY 2010–REVISED JANUARY 2012
www.ti.com
NOISE MEASUREMENTS
NOTE
The ADS1294R/6R/8R channel performance differs from the ADS1294/6/8 in regards to
respiration circuitry found on channel one. Unless otherwise noted, ADS129x refers to all
specifications and functional descriptions of the ADS1294, ADS1296, ADS1298,
ADS1294R, ADS1296R, and ADS1298R.
The ADS129x noise performance can be optimized by adjusting the data rate and PGA setting. As the averaging
is increased by reducing the data rate, the noise drops correspondingly. Increasing the PGA value reduces the
input-referred noise, which is particularly useful when measuring low-level biopotential signals. Table 1 and
Table 2 summarize the noise performance of the ADS129x in the High-Resolution (HR) mode and Low-Power
(LP) mode, respectively, with a 3V analog power supply. Table 3 and Table 4 summarize the noise performance
of the ADS129x in the HR mode and LP mode, respectively, with a 5V analog power supply. The data are
representative of typical noise performance at T
A
= +25°C. The data shown are the result of averaging the
readings from multiple devices and are measured with the inputs shorted together. A minimum of 1000
consecutive readings are used to calculate the RMS and peak-to-peak noise for each reading. For the two
highest data rates, the noise is limited by quantization noise of the ADC and does not have a gaussian
distribution. Thus, the ratio between rms noise and peak-to-peak noise is approximately 10. For the lower data
rates, the ratio is approximately 6.6.
Table 1 to Table 4 show measurements taken with an internal reference. The data are also representative of the
ADS129x noise performance when using a low-noise external reference such as the REF5025.
Table 1. Input-Referred Noise (μV
RMS
/μV
PP
) in High-Resolution Mode
3V Analog Supply and 2.4V Reference
(1)
DR BITS OF OUTPUT –3dB
CONFIG1 DATA RATE BANDWIDTH PGA PGA PGA PGA PGA PGA PGA
REGISTER (SPS) (Hz) GAIN = 1 GAIN = 2 GAIN = 3 GAIN = 4 GAIN = 6 GAIN = 8 GAIN = 12
000 32000 8398 335/3553 168/1701 112/1100 85/823 58/529 42.5/378 28.6/248
001 16000 4193 56/613 28/295 18.8/188 14.3/143 9.7/94 7.4/69 5.2/44.3
010 8000 2096 12.4/111 6.5/54 4.5/37.9 3.5/29.7 2.6/21.7 2.2/17.8 1.8/13.8
011 4000 1048 6.1/44.8 3.2/23.3 2.4/17.1 1.9/14.0 1.5/11.1 1.3/9.7 1.2/8.5
100 2000 524 4.1/27.8 2.2/15.4 1.6/11.0 1.3/9.1 1.1/7.3 1.0/6.5 0.9/6.0
101 1000 262 2.9/19.0 1.6/10.1 1.2/7.5 1.0/6.2 0.8/5.0 0.7/4.6 0.6/4.1
110 500 131 2.1/12.5 1.1/6.8 0.9/5.1 0.7/4.3 0.6/3.5 0.5/3.1 0.5/2.9
(1) At least 1000 consecutive readings were used to calculate the RMS and peak-to-peak noise values in this table.
Table 2. Input-Referred Noise (μV
RMS
/μV
PP
) in Low-Power Mode
3V Analog Supply and 2.4V Reference
(1)
DR BITS OF OUTPUT –3dB
CONFIG1 DATA RATE BANDWIDTH PGA PGA PGA PGA PGA PGA PGA
REGISTER (SPS) (Hz) GAIN = 1 GAIN = 2 GAIN = 3 GAIN = 4 GAIN = 6 GAIN = 8 GAIN = 12
000 16000 4193 333/3481 166/1836 111/1168 84/834 56/576 42/450 28/284
001 8000 2096 56/554 28/272 19/177 14.3/133 9.7/85 7.4/64 5.0/42.4
010 4000 1048 12.5/99 6.5/51 4.5/35.0 3.4/25.9 2.4/18.8 2.0/14.5 1.5/11.3
011 2000 524 6.1/41.8 3.2/22.2 2.3/15.9 1.8/12.1 1.4/9.3 1.2/7.8 1.0/6.7
100 1000 262 4.1/26.3 2.2/14.6 1.6/9.9 1.3/8.1 1.0/6.2 0.8/5.4 0.7/4.7
101 500 131 3.0/17.9 1.6/9.8 1.1/6.8 0.9/5.7 0.7/4.2 0.6/3.6 0.5/3.4
110 250 65 2.1/11.9 1.1/6.3 0.8/4.6 0.7/4.0 0.5/3.0 0.5/2.6 0.4/2.4
(1) At least 1000 consecutive readings were used to calculate the RMS and peak-to-peak noise values in this table.
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