Hall Effect Sensor Recommendation?

Does anyone have guidance for a hall sensor for the following case:

I need to power a circuit when a magnet is removed. It is to detect when a door or window has been opened.

I have a great working circuit for a Normally Closed reed switch, but since the reed switch is mechanical, it has proven unreliable. The reed switch pulls a P-MOSFET low to trigger power to my microcontroller, which then latches the power in by N-MOSFET...should the door or window shut.

I'm confused by Open Drain & Open Collector type hall effect sensors. Does anyone have guidance for a replacement for the reed switch? I'm operating on 3.3V.

Thanks,

Sean

Top Replies

dougw over 6 years ago

Allegro A3213EUA-TAllegro A3213EUA-T is a low voltage Hall switch that would work, but the gate would need a pull down resistor and the switch would need to connect to 3.3V to get the polarity you want.
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Sean_Miller over 6 years ago in reply to dougw

The datasheet looks dead on.

As fast as you answered, I'm torn between I wasted 5 hours over three evenings researching, or glad I learned a little on the journey. My wife would say the former. :-)

Thanks so much!
Sean
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colporteur over 6 years ago in reply to Sean_Miller

Do not be discourage by your investment of 5 hours. It would be ideal if we could hand off our experience to those coming after us so they don't have to invest as much. Unfortunately, time is a requirement to gain experience. Once obtained it can't be taken from you.

Based on my 37 years in technology the knowledge from the 5 hour experiences is sometimes transferable and permits us to reduce the time we invest to gain other experience.

Sean
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