The Adafruit ALS-PT19 is a compact analog light sensor that provides a simple voltage output proportional to ambient light intensity. Its spectral response closely matches that of the human eye, thanks to a high infrared rejection ratio — making it ideal as an RoHS-compliant upgrade from traditional photocells.

Wiring is straightforward: connect power (2.5–5.5V), ground, and read the analog voltage on the OUT pin. The voltage increases as the sensor detects more light.

Key Features

• Analog Output – Simple voltage output proportional to light level, read with any ADC
• Human-Eye Spectral Response – High infrared rejection for accurate ambient light sensing
• Wide Voltage Range – Operates from 2.5V to 5.5V
• RoHS Compliant – Suitable for projects requiring lead-free components
• Compact Breakout – Tiny PCB with simple three-pin interface

Ideal For

• Ambient light level detection
• Automatic backlight or LED brightness control
• Day/night sensing
• Replacing photocells in RoHS-compliant designs

Package Contents

• 1× Adafruit ALS-PT19 Analog Light Sensor Breakout