The A1180, A1181, A1182, and A1183 devices are sensitive, two-wire, unipolar, Hall effect switches. The operate point, BOP, can be field-programmed, after final packaging of the sensor and placement into the application. This advanced feature allows the optimization of the sensor switching performance, by effectively accounting for variations caused by mounting tolerances for the device and the target magnet.

This family of devices are produced on the Allegro MicroSystems advanced BiCMOS wafer fabrication process, which implements a patented, high-frequency, chopper-stabilization technique that achieves magnetic stability and eliminates the offsets that are inherent in single-element devices exposed to harsh application environments. Commonly found in a number of automotive applications, the A1180-83 family of devices are utilized to sense: seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position.

Two-wire unipolar switches are particularly advantageous in price-sensitive applications, because they require one less wire than the more traditional open-collector output switches. Additionally, the system designer gains inherent diagnostics because output current normally flows in either of two narrowly-specified ranges. Any output current level outside of these two ranges is a fault condition. The A1180-83 family of devices also features on-chip transient protection, and a Zener clamp to protect against overvoltage conditions on the supply line.

The output currents of the A1181 and A1183 switch HIGH in the presence of a south polarity magnetic field of sufficient strength; and switch LOW otherwise, including when there is no significant magnetic field present. The A1180 and A1182 have inverted output current levels: switching LOW in the presence of a south polarity magnetic field of sufficient strength, and HIGH otherwise. The devices also differ in their specified LOW current supply levels.

Also see: A1184, A1185, and A1186.

Factory-programmed versions are also available. Refer to: A1140, A1141, A1142, and A1143.