Hall-effect speed and direction sensor IC with built-in hysteresis detection

The new A1232 from Allegro MicroSystems Europe is a Hall-effect speed and direction sensor IC with built-in hysteresis detection. The A1232 is a highly-sensitive temperature-stable magnetic sensing device that is ideal for use in ring magnet based speed and direction sensing systems in harsh automotive and industrial environments. It is the first device of its kind with the ability to detect when it powers up in the magnetic hysteresis band. This feature reduces angle accuracy error, which can occur when edges are missed at start-up, says the company. The Allegro A1232 includes dual Hall elements spaced 1.63 mm apart that are photo-lithographically aligned to within 1 µm. The precise spacing of the sensing elements eliminates a major manufacturing hurdle encountered when using fine-pitch ring magnets. The signals from the dual Hall elements are encoded into logic outputs representing the speed and direction of the target. Factory trimming and Allegro’s proprietary chopper stabilisation and dynamic offset cancellation techniques provide precise, symmetrical magnetic switch-points over a wide range of operating conditions. A built-in voltage regulator, short-circuit protected outputs, internal Zener clamps, reverse battery protection, and a -40°C to +150°C operating range give the A1232 the ruggedness demanded by automotive applications. The device targets motor applications in the automotive market such as window lifts, sunroofs, sliding doors and tail/trunk lift gates. It is also suitable for non-automotive applications such as garage door openers and window blinds.