How to select the right product for your application

• Data loggers

• LSB: the smallest voltage increment that can be measured by the digitizer. It is defined as the maximum voltage amplitude divided by the largest quantifiable value by the A/D converter . Example: with a +/-5V maximum excursion, the LSB for a 24bit AD converter is 10/2²⁴=596nV.

• Dynamic range: the theoretical definition of the dynamic range of an A/D converter is given as the ratio of the power of a full scale sine wave versus the power of the shortened input noise. For a regular successive approximation converter with a LSB of amplitude q, the statistical digitization noise power is q²/12. If N is the number of bits of the converter, a full scale sine wave power is given by (2^N-1 *q)²/2.

• Selectable gain: in some particular cases, selectable gains may be usefull to take into account the variability of the maximum excursion expected for different sensors. Note that software selectable gains always add noise since more electronics is involved in the analogical circuitery.

• Full scale span of the sensor: as mentionned earlier, the full scale span of the sensor, or the maximum excursion will determine the appropriate LSB (and maximum input span)..