ADUCM360/361: ADC ENOB Calculation

Document created by analog-archivist Employee on Feb 23, 2016
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In the ADuCM360/361 datasheet - how is the ADC Effective number of  bits figure
calculated
from the noise tables?

 

The RMS noise is derived by taking 200 ADC conversion results with an internal
short selected  as the ADC input (Same Ain channel selected as the positive and
negative input to the ADC).
The RMS Effective Number of bits is calculated as follows:

            RMS ENOB = log10 (Voltage span/RMS noise)
            _________________________________________
                   
                           log10(2)

The voltage span is 2x VREF when 2's complement ADC output results are selected
via  ADCxCON[18]. (Bipolar ADC readings)

     Pk-Pk ENOB = log10 (Voltage span/Pk-Pk noise)  where pk-pk noise = RMS
noise x 6.6
                         ________________________________
                                
                                     log10(2)

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