GA1A12S202 Log-scale Analog Light Sensor

This sensor is logarithmic over a large dynamic range of 3 to 55,000 Lux, so it has a lot of sensitivity at low light levels but is also nearly impossible to “max out” so you can use it indoors or outdoors without changing code or calibration. Since the sensor is fabricated on a chip, there are also fewer manufacturing variations, so you won’t have to calibrate the sensor from one board to another.

Using the sensor is easy as pie: connect the Vin to 2.3-6VDC, Gnd to ground and measure the analog output on OUT. It will range up to 3V (at extremely bright outdoor sunlight). On an Arduino, just use analogRead() with the OUT pin connected to an analog pin. For more information including graphs, power consumption, etc check out the datasheet in the Tech Details tab. On this breakout we placed a 68KΩ resistor from OUT to ground to turn the current into a voltage.

Technical Details
GA1A1S202WP Datasheet

• Power with 2.3-6V
• Onboard 68K load resistor for max 3V analog output
• 0.2 grams
• 0.4″ x 0.5″ x 0.06″ (10mm x 13mm x 1.5mm)
• 0.1″ (2.5mm) mounting hole

Learn: Adafruit GA1A12S202 Log-scale Analog Light Sensor