Allegro Microsystems Surface Hall Effect Sensor 2.4 V 5.5V, SOT-23, 3-Pin

The Allegro Microsystems A3213/4 ultra-sensitive, pole independent Hall-effect switches with a latched digital output are aimed at use in battery-operated, portable equipment. Their 2.4 V to 5.5 V operation and a unique clocking scheme reduces the average operating power use. The A3213 to 825 μW and the A3214 to 14 μW (typical, at 2.75 V).

Either a north or south pole turns on the output.

They include a Hall-voltage generator, small-signal amplifier, chopper stabilisation, a latch, and a MOSFET output.