Digital Light Sensor

Description

Working Principle

A photodiode is a PN-junction diode. There is a region called depletion region at the interface between P-type and N-type.

Light carries energy in the form of small energy packets called Photons. When the depletion region is illuminated by photons of energy enough to break covalent interatomic bonds, it creates a pair – an electron(black spots in figure), and a hole(white spots in figure). Electrons continue flowing down the wire to the voltage source, and to the P-type. The holes cannot move in wires, so they recombine with incoming electrons at the P-type. The photocurrent generated will be converted into voltage, then from analog values into digital values, finally output illuminance in LUX.