Datasheet
ADS1194, ADS1196
ADS1198
www.ti.com
SBAS471C –APRIL 2010– REVISED NOVEMBER 2011
NOISE MEASUREMENTS
The ADS1194/6/8 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 summarizes the noise performance of the ADS1194/6/8, with a 3V analog power supply. Table 2
summarizes the noise performance of the ADS1194/6/8 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 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. The ratio
between rms noise and peak-to-peak noise for these two data rates are approximately 10. For the lower data
rates, the ratio is approximately 6.6.
Table 1 and Table 2 show measurements taken with an internal reference. In many of the settlings, espeically at
the lower data rates, the inherent device noise is less than 1LSB. For these cases, the noise is rounded up to
1LSB. The data are also representative of the ADS1194/6/8 noise performance when using a low-noise external
reference such as the REF5025.
Table 1. Input-Referred Noise (μV
PP
)
3V Analog Supply and 2.4V Reference
(1)(2)
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 8000 2096 2930 1470 937 681 436 319 205
001 4000 1048 563 265 173 124 77 56 36
010 2000 524 104 51 33 24 17 13 9.5
011 1000 262 73.3 36.6 24.4 18.3 12.2 9.2 6.1
100 500 131 73.3 36.6 24.4 18.3 12.2 9.2 6.1
101 250 65 73.3 36.6 24.4 18.3 12.2 9.2 6.1
110 125 32.5 73.3 36.6 24.4 18.3 12.2 9.2 6.1
(1) At least 1000 consecutive readings were used to calculate the peak-to-peak noise values in this table.
(2) For data rates less than 2kSPS, the noise is rounded up to 1LSB. Input-referred LSB in volts = (2 × V
REF
/(Gain × 2
16
)).
Table 2. Input-Referred Noise (μV
PP
)
5V Analog Supply and 4V Reference
(1)(2)
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 8000 2096 4923 2450 1598 1196 765 560 362
001 4000 1048 959 481 307 222 142 100 63
010 2000 524 166 81 52 40 26 19 12.3
011 1000 262 122.1 61.1 40.7 30.5 20.4 15.3 10.2
100 500 131 122.1 61.1 40.7 30.5 20.4 15.3 10.2
101 250 65 122.1 61.1 40.7 30.5 20.4 15.3 10.2
110 125 32.5 122.1 61.1 40.7 30.5 20.4 15.3 10.2
(1) At least 1000 consecutive readings were used to calculate the peak-to-peak noise values in this table.
(2) For data rates less than 2kSPS, the noise is rounded up to 1LSB. Input-referred LSB in volts = (2 × V
REF
/(Gain × 2
16
)).
Table 3. Typical WCT Performance
ANY ONE ANY TWO ALL THREE
PARAMETER (A, B, or C) (A+B, A+C, or B+C) (A+B+C) UNIT
Noise 563 404 330 nV
RMS
Power 36 40 44 μA
–3dB BW 30 59 89 kHz
Slew rate BW limited BW limited BW limited —
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