ADS1294CZXGR datasheet(22/114 Pages) TI2

22 / 114 page

ADS1294, ADS1294R, ADS1296, ADS1296R, ADS1298, ADS1298R

SBAS459K – JANUARY 2010 – REVISED AUGUST 2015

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8 Parameter Measurement Information

8.1 Noise Measurements

NOTE

The ADS129xR channel performance differs from the ADS129x 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. ADS129xR refers to all specifications and

functional descriptions of only the ADS1294R, ADS1296R, and ADS1298R.

Optimize the ADS129x noise performance by adjusting the data rate and PGA setting. Reduce the data rate to

increase the averaging, and the noise drops correspondingly. Increase the PGA value to reduce the input-

referred noise. This lowered noise level is particularly useful when measuring low-level biopotential signals.

Table 1 and Table 2 summarize the noise performance of the ADS129x in high-resolution (HR) mode and low-

power (LP) mode, respectively, with a 3-V analog power supply. Table 3 and Table 4 summarize the noise

performance of the ADS129x in HR and LP modes, respectively, with a 5-V analog power supply. The data are

representative of typical noise performance at TA = 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

μVRMS (μVPP) in High-Resolution Mode

3-V Analog Supply and 2.4-V Reference(1)

DR BITS OF

OUTPUT

–3-dB

CONFIG1

DATA RATE

BANDWIDTH

PGA

(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)

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)

1.3 (9.1)

1.1 (7.3)

1 (6.5)

0.9 (6)

101

1000

262

2.9 (19)

1.6 (10.1)

1.2 (7.5)

1 (6.2)

0.8 (5)

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 used to calculate the RMS and peak-to-peak noise values in this table.

Table 2. Input-Referred Noise

μVRMS (μVPP) in Low-Power Mode

3-V Analog Supply and 2.4-V Reference(1)

DR BITS OF

OUTPUT

–3-dB

CONFIG1

DATA RATE

BANDWIDTH

PGA

(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 (42.4)

010

4000

1048

12.5 (99)

6.5 (51)

4.5 (35)

3.4 (25.9)

2.4 (18.8)

2 (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 (6.7)

100

1000

262

4.1 (26.3)

2.2 (14.6)

1.6 (9.9)

1.3 (8.1)

1 (6.2)

0.8 (5.4)

0.7 (4.7)

101

500

131

3 (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

2.1 (11.9)

1.1 (6.3)

0.8 (4.6)

0.7 (4)

0.5 (3)

0.5 (2.6)

0.4 (2.4)

(1)

At least 1000 consecutive readings used to calculate the RMS and peak-to-peak noise values in this table.

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