Datasheet
ADS1146
ADS1147
ADS1148
SBAS453F –JULY 2009–REVISED APRIL 2012
www.ti.com
NOISE PERFORMANCE
The ADS1146/7/8 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, particularly useful when measuring low-level signals. Table 1 and Table 2
summarize noise performance of the ADS1146/7/8. The data are representative of typical noise performance at
T = +25°C. The data shown are the result of averaging the readings from multiple devices and were measured
with the inputs shorted together.
Table 1 lists the input-referred noise in units μV
PP
. In many of the settings, especially at lower data rates, the
inherent device noise is less than 1LSB. For these cases, the noise is rounded up to 1LSB. Table 2 lists the
corresponding data in units of ENOB (effective number of bits) where:
ENOB = ln(Full-Scale Range/Noise)/ln(2) (1)
Table 1. Noise in μV
PP
At V
REF
= 2.048V, AVDD = 5V, and AVSS = 0V
PGA SETTING
DATA RATE
(SPS) 1 2 4 8 16 32 64 128
5 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
0.98
(1)
0.49
(1)
10 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
0.98
(1)
0.49
(1)
20 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
0.98
(1)
0.55
40 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
0.98
(1)
0.75
80 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
1.09 0.98
160 62.50
(1)
31.25
(1)
15.63
(1)
7.81
(1)
3.91
(1)
1.95
(1)
1.88 1.57
320 62.50
(1)
35.30 17.52 8.86 4.35 3.03 2.44 2.34
640 93.06 45.20 18.73 12.97 6.51 4.20 3.69 3.50
1000 284.59 129.77 61.30 33.04 16.82 9.08 5.42 4.65
2000 273.39 130.68 67.13 36.16 19.22 9.87 6.93 6.48
(1) Peak-to-peak noise rounded up to 1LSB.
Table 2. Effective Number of Bits From Peak-to-Peak Noise
At V
REF
= 2.048V, AVDD = 5V, and AVSS = 0V
PGA SETTING
DATA RATE
(SPS) 1 2 4 8 16 32 64 128
5 16 16 16 16 16 16 16 16
10 16 16 16 16 16 16 16 16
20 16 16 16 16 16 16 16 15.8
40 16 16 16 16 16 16 16 15.4
80 16 16 16 16 16 16 15.8 15.0
160 16 16 16 16 16 16 15.1 14.3
320 16 15.8 15.8 15.8 15.8 15.4 14.7 13.7
640 15.4 15.5 15.7 15.3 15.3 14.9 14.1 13.2
1000 13.8 13.9 14.0 13.9 13.9 13.8 13.5 12.7
2000 13.9 13.9 13.9 13.8 13.7 13.7 13.2 12.3
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