A115x Hall-Effect Unipolar Switches

By Allegro MicroSystems, LLC 198

A115x Hall-Effect Unipolar Switches

Allegro's A115x family of devices are the next generation of two-wire, unipolar, Hall-effect switches; factory trimmed to optimize the accuracy of the magnetic switch points. These devices employ a patented, high frequency, four-phase, chopper-stabilization technique to achieve magnetic stability over temperature and to eliminate offset inherent in single-element devices, when exposed to harsh automotive environments. Additionally, this advanced chopping technique provides significantly reduced jitter and faster power-on time.

Commonly found in a number of automotive applications, the A1152/3/5/6 devices are utilized to sense: seat track position, seat belt buckle presence, hood/trunk latching, steering lock position, and in shift selectors. Two-wire, unipolar switches require one less wire for operation versus the more traditional open-collector output switches. Additionally, the user gains diagnostics, as there is always current at one of two specified levels. Any output current outside of these two narrow ranges is a fault condition.

  • High speed, 4-phase chopper stabilization
  • Low switch-point drift throughout temperature range
  • Low sensitivity to thermal and mechanical stresses
  • Industry leading ISO 7637-2 performance through use of proprietary, 40 V clamping structures
  • Solid-state reliability
  • Robust EMC and ESD performance
  • On-chip protection
    • Supply transient protection
    • Reverse battery protection
    • On-board voltage regulator
    • 3.0 V to 24 V operation