The underside (pin side) of the PID-A1 (or PID-AH) sensor has a small circular gold plated well that can be left open or be filled with solder. If the well is not filled with the solder, the on board regulator is enabled therefore a regulated or unregulated supply between 3.6 – 18.0 V may be supplied and the internal voltage will be regulated to 3.3 V.
If the solder well is filled with solder, the sensor’s on board regulator is disabled therefore a regulated supply of 2.8 – 3.6 V is required. This supply should be stable to within 10 mV to maintain a stable light intensity.
For more information, see Application Note AAN 302