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Appendix B - Noise and Resolution Tables

The following tables provide typical noise levels of the UE9 under ideal conditions. The resulting voltage resolution is then calculated based on the noise levels. Also see the LJTick-InAmp datasheet which provides similar tables with the instrumentation amplifier installed.

Measurements were taken with AIN0 connected to GND with a short jumper wire, or from internal ground channel #15. Similar results were obtained with other quiet signals such as a 2.048 reference (REF191 from Analog Devices), a 1.5 volt D-cell battery, and a temperature sensor (LM34CAZ from National Semiconductor).

All “counts” data are aligned as 24-bit values. To equate to counts at a particular resolution (Res) use the formula counts/(2^(24-Res)). For instance, with the UE9 set to 12-bit resolution and the 0-5 volt range, there are 8192 counts of noise when looking at 24-bit values. To equate this to 12-bit data, we take 8192/(2^12) which equals 2 counts of noise when looking at 12-bit values.

Noise-free data is determined by taking 128 readings and subtracting the minimum value from the maximum value.

RMS and Effective data are determined from the standard deviation of 128 readings. In other words, the RMS data represents most readings, whereas noise-free data represents all readings.

Table B-1. Resolution and noise table 

Resolution = 0-12            
Range Peak-To-Peak Noise Noise-Free Resolution Noise-Free Resolution RMS Noise Effective Resolution Effective Resolution
volts counts bits µV counts bits µV
±5 8192 11 4,883 2200 12.8 1,402
0-5 8192 11 2,441 2200 12.8 701
0-2.5 20480 9.7 3,006 4100 12 610
0-1.25 36864 8.8 2,804 7800 11.1 569
0-0.63 69632 7.9 2,638 14500 10.1 574
             
Resolution = 14            
Range Peak-To-Peak Noise Noise-Free Resolution Noise-Free Resolution RMS Noise Effective Resolution Effective Resolution
volts counts bits µV counts bits µV
±5 2816 12.5 1,726 550 14.9 327
0-5 2816 12.5 863 550 14.9 164
0-2.5 4864 11.8 701 940 14.1 142
0-1.25 8448 11 610 1650 13.3 124
0-0.63 16384 10 615 3300 12.3 125
             
Resolution = 16            
Range Peak-To-Peak Noise Noise-Free Resolution Noise-Free Resolution RMS Noise Effective Resolution Effective Resolution
volts counts bits µV counts bits µV
±5 720 14.5 432 140 16.9 82
0-5 720 14.5 216 140 16.9 41
0-2.5 1200 13.8 175 230 16.2 33
0-1.25 2224 12.9 164 400 15.4 29
0-0.63 4256 11.9 165 775 14.4 29
             
Resolution = 17            
Range Peak-To-Peak Noise Noise-Free Resolution Noise-Free Resolution RMS Noise Effective Resolution Effective Resolution
volts counts bits µV counts bits µV
±5 352 15.5 216 75 17.8 44
0-5 352 15.5 108 75 17.8 22
0-2.5 620 14.7 94 120 17.1 18
0-1.25 1060 14 76 210 16.3 15
0-0.63 2068 13 77 400 15.4 15
             
Resolution = 18+ (UE9-Pro)            
Range Peak-To-Peak Noise Noise-Free Resolution Noise-Free Resolution RMS Noise Effective Resolution Effective Resolution
volts counts bits µV counts bits µV
±5 110 17.2 66 20 19.7 12
0-5 90 17.5 27 17 19.9 5