The light illuminating the sensor area is known because the LIGHTSOURCE01EVM can provide a constant and stable output. This information can be used to determine the compensation factor of each unit, where the compensation factor is the lux from the light source divided by the lux read by the sensor. On a production line, the compensation factor can then be stored for each unit in a form of non-volatile memory.

Figure 2-16 Production Line Calibration

This is also done on the system-level, where implementing dark cover glass and other optical devices like lenses, diffusers, and light guides is desirable in a design. A compensation factor can be calculated in a similar manner to what is obtained for device-level calibration. For more information, see also the Precision labs series: Ambient light sensors web page.