The A1150, A1152, A1153, A1155, A1156, A1157, and A1158 comprise a family of two-wire, unipolar, Hall-effect switches, which are factory-trimmed to optimize magnetic switchpoint accuracy. These devices are produced on the Allegro® advanced BiCMOS wafer fabrication process, which implements a patented high frequency, 4-phase, chopper-stabilization technique. This technique achieves magnetic stability over the full operating temperature range, and eliminates offsets inherent in devices with a single Hall element that are exposed to harsh application environments.
The A115x family has a number of automotive applications. These include sensing seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position.
Two-wire unipolar switches are particularly advantageous in cost-sensitive applications because they require one less wire for operation versus the more traditional open-collector output switches. Additionally, the system designer inherently gains diagnostics because there is always output current flowing, which should be in either of two narrow ranges. Any current level not within these ranges indicates a fault condition.
All family members are offered in two package styles. The LH is a SOT-23W style, miniature, low profile package for surface-mount applications. The UA is a 3-pin, ultra-mini, single inline package (SIP) for through-hole mounting. Both packages are lead (Pb) free, with 100% matte tin leadframe plating.