The A1140, A1141, A1142, and A1143 devices are sensitive, two-wire, unipolar, Hall effect switches that are factoryprogrammed at end-of-line to optimize magnetic switchpoint accuracy. These devices use a patented high frequency chopperstabilization technique, produced using the Allegro advanced BiCMOS wafer fabrication process, to achieve magnetic stability and to eliminate offset inherent in single-element devices exposed to harsh application environments.