The US1881LUA is a unipolar Hall-effect sensor IC, which is an electronic component used to detect and measure the presence of magnetic fields. These are commonly used for position sensing, speed measurement and proximity detection, and an excellent alternative to a reed switch. Hall sensors tend to be smaller and far more durable than a a reed switches, which tends to be considerably larger, and made of delicate glass tubing.

Similar to a reed switch, when a magnet is brought near the hall sensor, it will cause the output pin to toggle. This specific hall sensor is a latching type, meaning each time the magnet approaches it will switch to the opposite state it was in previous. For applications requiring a non-latching version, we also carry the non-latching AH1815 Hall-Effect Sensor as well.