A1120/1/2/3/5 Chopper Stabilised Hall Effect Sensor Switches, Allegro Microsystems The Allegro Microsystems A1120, A1121, A1122, A1123, and A1125 Hall-effect, unipolar switches are temperature-stable and stress-resistant sensor ICs. High temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally caused by device over-molding, temperature dependencies, and thermal stress.

They include a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilisation, Schmitt trigger, and a short circuit protected open-drain output to sink up to 25 mA. The voltage regulator enables supply voltages of 3 V to 24 V.

For the A1120, A1121, A1122, and A1123, a south pole turns on the output and removal turns off the output. For the A1125, it is reversed and the south pole turns off the A1125 output. Unipolar switchpoints
Resistant to physical stress
Superior temperature stability
Output short circuit protection
Operation from unregulated supply