Ultra-sensitive micropower Hall-effect switch IC from Allegro MicroSystems

Unlike many Hall-effect switches, both north and south polarity magnetic fields of sufficient strength activate output switching to either ‘off’ or ‘on’. In addition, the A1172 incorporates two push-pull outputs configured so that one output switches off in the absence of sufficient magnetic field while the other output switches on in the absence of a magnetic field.



This polarity independence, as well as the minimal power requirement, allows the A1172 to easily replace reed switches, providing superior reliability and ease of manufacturing while eliminating the requirement for signal conditioning.



The A1172 includes, on a single silicon chip, a Hall-effect voltage generator, a small-signal amplifier, chopper stabilisation circuitry, a latch, and a MOSFET output. Chopper stabilisation provides improved stability through dynamic offset cancellation, reducing the residual offset voltage normally caused by device over moulding, temperature dependence and thermal stress.



This new device is designed to offer a magnetically optimised solution for battery-operated, consumer equipment and is available in a 4-pin wafer level chip scale package measuring only 1 x 1 x 0.5 mm. This package is smaller than most plastic packages, which reduces the printed circuit board area consumed by these switches.