onsemi H21A2

The H21A2 is a transmissive opto sensor with a phototransistor output, designed for slotted switch applications. It features a 3.15 mm slot width and operates with an input current of 20 mA and a collector-emitter voltage rating of 30 V. The device supports a maximum power dissipation of 150 mW and operates over a temperature range of -55°C to +100°C. It is housed in a 4-pin package with pinout: pin 1 anode, pin 2 cathode, pin 3 collector, and pin 4 emitter. The sensor has a minimum current transfer ratio of 2.00 and a maximum emitter-collector voltage of 4.5 V. Its dimensions are 0.745 to 0.755 inches (18.9 to 19.2 mm) in length, 0.457 to 0.472 inches (11.6 to 12.0 mm) in width, and 0.34 to 0.39 inches (8.5 to 10.0 mm) in height.