Datasheet

ADS1299
SBAS499A –JULY 2012–REVISED AUGUST 2012 www.ti.com
PARAMETRIC MEASUREMENT INFORMATION
NOISE MEASUREMENTS
The ADS1299 noise performance can be optimized by adjusting the data rate and PGA setting. When 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 to Table 4
summarize the ADS1299 noise performance with a 5-V 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 lower data rates, the ratio is
approximately 6.6.
Table 1 shows measurements taken with an internal reference. The data are also representative of the ADS1299
noise performance when using a low-noise external reference such as the REF5025.
Table 1. Input-Referred Noise (μV
RMS
/ μV
PP
) in Normal Mode
5-V Analog Supply and 4.5-V Reference
(1)
PGA PGA
GAIN = 1 GAIN = 2
DR BITS OF OUTPUT NOISE- NOISE-
CONFIG1 DATA RATE –3-dB FREE FREE
REGISTER (SPS) BANDWIDTH (Hz) μV
RMS
μV
PP
SNR (dB) BITS ENOB μV
RMS
μV
PP
SNR (dB) BITS ENOB
000 16000 4193 21.70 151.89 103.3 15.85 17.16 10.85 75.94 103.3 15.85 17.16
001 8000 2096 6.93 48.53 113.2 17.50 18.81 3.65 25.52 112.8 17.43 18.74
010 4000 1048 4.33 30.34 117.3 18.18 19.49 2.28 15.95 116.9 18.11 19.41
011 2000 524 3.06 21.45 120.3 18.68 19.99 1.61 11.29 119.9 18.60 19.91
100 1000 262 2.17 15.17 123.3 19.18 20.49 1.14 7.98 122.9 19.10 20.41
101 500 131 1.53 10.73 126.3 19.68 20.99 0.81 5.65 125.9 19.60 20.91
110 250 65 1.08 7.59 129.3 20.18 21.48 0.57 3.99 128.9 20.10 21.41
111 n/a n/a — — — — — — — — — —
(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 Normal Mode
5-V Analog Supply and 4.5-V Reference
(1)
PGA PGA
GAIN = 4 GAIN = 6
DR BITS OF OUTPUT NOISE- NOISE-
CONFIG1 DATA RATE –3-dB FREE FREE
REGISTER (SPS) BANDWIDTH (Hz) μV
RMS
μV
PP
SNR (dB) BITS ENOB μV
RMS
μV
PP
SNR (dB) BITS ENOB
000 16000 4193 5.60 39.23 103.0 15.81 17.12 3.87 27.10 102.7 15.76 17.06
001 8000 2096 1.98 13.87 112.1 17.31 18.62 1.31 9.19 112.1 17.32 18.62
010 4000 1048 1.24 8.66 116.1 17.99 19.29 0.93 6.50 115.1 17.82 19.12
011 2000 524 0.88 6.13 119.2 18.49 19.79 0.66 4.60 118.1 18.32 19.62
100 1000 262 0.62 4.34 122.2 18.99 20.29 0.46 3.25 121.1 18.81 20.12
101 500 131 0.44 3.07 125.2 19.49 20.79 0.33 2.30 124.1 19.31 20.62
110 250 65 0.31 2.16 128.2 19.99 21.30 0.23 1.62 127.2 19.82 21.13
111 n/a n/a — — — — — — — — — —
(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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