Allegro Microsystems Surface Mount Hall Effect Sensor Switch, SOT-23, 3-Pin

The A3211/2 are ultrasensitive, pole independent, Hall-effect switches with latched digital output. Their 2.5 V to 3.5 V operation and unique clocking scheme reduces the average operating power to less than 15 μW with a 2.75 V supply.

Either a north or south pole turns on the output in the A3212 and removing the magnetic field turns the output is off. This is reversed on the A3211.

Chopper stabilisation improves stability which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.

Included on the chip is a Hall-voltage generator, small-signal amplifier, chopper stabilisation, a latch, and a MOSFET output.

Hall Effect Sensors, Allegro MicroSystems