A3144 Hall Effect Sensor

Operational notes:

IMPORTANT: Pin assignment is with SMALL face facing forward. Large face of device is in the back. Pins are 1, 2, 3 - from Left to Right.

Pin 1 (left pin, with small face forward): VCC (4.5-24VDC)

Pin 2: GND (center Pin)

Pin 3: Output - open collector active low, right hand pin with small face forward.

NOTE: Output is open collector, and must be pulled high.

Pull-up on output can be wired to 3.3V supply instead of 5V supply for part (Sensor spec requires 4.5V or greater for operation) for voltage levels compatible with Pi inputs.

Also can wire LED in series with pullup for visual output. If doing this, wire that in parallel to pull-up on output pin so that output pin swings 3.3 to ~0 for proper in readings, while LED will glow when pin is down.

Either large or small face of A3144 may be used as the sensor side. Does not respond to magnet being passed over top of sensor - must be passed by either front or back face of sensor. Pole of magnet that must be passed depends on whether it is the front or the back face.