ADS1232
ADS1234
www.ti.com
SBAS350–JUNE 2005
NOISE PERFORMANCE
The ADS1232/1234 offer outstanding noise performance that can be optimized for a givven full-scale range using
the on-chip programmable gain amplifier, Table 1, Table 2, Table 3, and Table 4 summarize the typical noise
performance with inputs shorted externally for different gains, data rates and voltage reference values.
The RMS and Peak-to-Peak noise are referred to the input. The Effective Number of Bits (ENOB) is defined as:
•
ENOB = ln (FSR/RMS noise)/ln(2)
The Noise Free Bits are defined as:
Noise-Free Bits = ln (FSR/Peak-to-Peak Noise)/ln(2)
Where FSR (Full-Scale Range) = VREF/Gain
•
Table 1. AVDD = 5V, VREF = 5V, Data Rate = 10SPS
GAIN
1
RMS NOISE
420nV
PEAK-TO-PEAK NOISE
ENOB (rms)
23.5
NOISE-FREE BITS
1.79µV
900nV
125nV
110nV
21.4
21.4
19.2
18.4
2
270nV
23.1
64
19nV
22.0
128
17nV
21.1
Table 2. AVDD = 5V, VREF = 5V, Data Rate = 80SPS
GAIN
1
RMS NOISE
1.36µV
850nV
PEAK-TO-PEAK NOISE
ENOB (rms)
21.8
NOISE-FREE BITS
8.3µV
5.5µV
307nV
247nV
19.2
18.8
18
2
21.5
64
48nV
20.6
128
44nV
19.7
17.2
Table 3. AVDD = 3V, VREF = 3V, Data Rate = 10SPS
GAIN
1
RMS NOISE
450nV
PEAK-TO-PEAK NOISE
ENOB (rms)
22.6
NOISE-FREE BITS
2.8µV
1.8µV
130nV
115nV
20
2
325nV
22.1
19.7
18.5
17.6
64
20nV
21.2
128
18nV
20.3
Table 4. AVDD = 3V, VREF = 3V, Data Rate = 80SPS
GAIN
1
RMS NOISE
2.2µV
PEAK-TO-PEAK NOISE
ENOB (rms)
20.4
NOISE-FREE BITS
12µV
6.8µV
340nV
254nV
17.9
17.8
17.1
16.5
2
1.2µV
20.2
64
54nV
19.7
128
48nV
18.9
7
BB [ BURR-BROWN CORPORATION ]
