Problem with A3213EUA-T, Hall Effect Switch

Hi,

hopefully somebody will be able to shed some light on my issue.

I am trying to sense the passing of the wheel in my gas meter using a A3213EUA-T, Hall Effect sensor SwitchView attachment Hall effect Sensor Switch A3213-4 datasheet.pdf.

I have wired it up on a stripboard as for the datasheet, with cloely coupled 0.1microfarad capacitor between Vdd and ground and a 10 picofarad capacitor between the output pin and ground. I have also inserted a 50kohm pull up resistor between Vdd and the output pin. nothing else is connected to the output pin.

The sensor works, but it doesn't behaves as suggested by the datasheet:

When there is sufficient magnetic the voltage between the output pin and ground goes to zero to suggest that enough current goes through the sensor to override the pull up resistor, so everything OK in this case.

However when no magnetic field is zero the voltage between the output pin and ground is only 0.6V instead of being very close to Vddv as for the datasheet, suggesting that the current through the pull up resistor is far from zero, as the datasheet would suggest (I make it about 70 uA, as opposed to max 1uA as suggested by the datasheet).

So the sensor is capable to "sense" but it only gives an output range of circa 0.6V.

Could someone take a look to see if I am missing something or there is something wrong with the sensors (I have 5 and they all behave in the same way).

In case the sensor behaves as it should, could someone suggest a way to use those 0.6V to trigger an interrupt in a Picaxe datalogger A110? I presume I would have to amplify the voltage from 0-0.6V to 0-5V.

I can post a photo of the stripboard if necessary.

Thanks in advance
Riccardo










and when

From your post it does sound like you have the sensor wired correctly, so the output should swing from close to 0 upto nearly Vdd.

Please post a photo of your stripboard, it could maybe be that the wiring is not exactly as you describe, maybe just a 'one hole out' type of error.

A problem shared is a problem solved,

I had indeed wired it up incorrectly. It turned up that the pin numbering for the two packages in the specsheet refers to different pins: for the LH surface mount package (1=Vdd,2=Vout,3=GND) whereas for the UA through hole package (1=Vdd, 2=GND, 3=Vout).

I had missed this detail and assumed that equal number meant same pin. All good experience.

It works now, many thanks for the pointer.

Riccardo