STS-8857 PDF Datasheet – Infrared Diode, Phototransistor

Part Number: STS-8857

Function: Infrared emitting diode and an NPN silicon phototransistor, Transmissive Switch Assembly

Manufacturer: Silonex


STS-8857 pdf datasheet


A transmissive switch assembly is an electronic component or device used to detect the presence or absence of an object or a particular condition by transmitting light through it and measuring the amount of light that passes through. These assemblies are often employed in a variety of applications, including industrial automation, optical sensing, and object detection.

The STS-8857 consists of an infrared emitting diode and an NPN silicon phototransistor mounted on
opposite sides of a 3.8 mm wide slot. Phototransistor switching takes place whenever an opaque object
passes through the slot. The polysulfone housing (2) reduces interference from ambient light and provides dirt and dust protection. The 40 cm minimum length wires simplify the connection to the PC board.

1. Receiver/Photodetector: The photodetector is positioned opposite the light source and is designed to detect the intensity of the light that passes through the object or condition being monitored. Common types of photodetectors used include photodiodes, phototransistors, or photointerrupters.


1. Non contact switching

2. Three wires for electrical connection

3. Fast switching speed


Absolute Maximum Ratings :

1. Operating & Storage Temperature -40°C to +85°C

2. Input Diode

3. Reverse Voltage 3 V

4. Continuous Forward Current 50 mA

5. Peak Forward Current (1ms pulse) 3 A

6. Power Dissipation (1) 100 mW



STS-8857 PDF Datasheet