The US1881 is an integrated Hall effect latched sensor. That's nice but what does it do? Holding a magnet near the sensor will cause the output pin to toggle. This makes for a robust presence sensor. A reed sensor also works nicely, but can be limited by the glass encapsulation and size. A hall effect sensor is much smaller, but can handle less current than a reed switch. The device includes an on-chip Hall voltage generator for magnetic sensing, a comparator that amplifies the Hall voltage, and a Schmitt trigger to provide switching hysteresis for noise rejection, and open-collector output. An internal bandgap regulator is used to provide temperature compensated supply voltage for internal circuits and allows a wide operating supply range. If a magnetic flux density larger than threshold Bop, DO is turned on (low). The output state is held until a magnetic flux density reversal falls below Brp causing DO to be turned off (high). Features: * 3.5V to 24V DC operation voltage * Low current consumption * Temperature compensation * Wide operating voltage range * Open-Collector pre-driver * 50mA maximum sinking output current * Reverse polarity protection * Lead Free Package: TO-92 Documents: * Datasheet * Bildr Tutorial https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2009-07-12 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2016-11-25 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2016-11-28 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2016-11-29 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2016-12-09 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2016-12-13 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2017-11-10 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2017-11-13 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2017-11-24 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2017-11-28 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2018-05-05 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2018-11-21 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2018-11-27 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2019-12-09 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2019-12-14 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2022-02-21 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2025-04-12 https://elecena.pl/product/865708/hall-effect-sensor-us1881-latching 2025-04-14