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DRV5056: Using DRV5056 as a bipolar device

Vincent Daanen
Prodigy 20 points
Part Number: DRV5056

Hello, 

from the datasheet, DRV5056 has a quiescent voltage of 0.6V ; and the output voltage will be below this value if the device is subjected to a 'negative' magnetic flux.

I plan to use a couple of DRV5056 with a MCU. 

My early experiments shown that when subjecting a DRV5056 to a negative magnetic flux, the output voltage goes down to a value of "26" (after conversion by ADC, i.e. 0.12V approx)

My questions are:

1) is it the reliable to rely on this property to discriminate 2 magnets ? or does this "property" is subjected to changes/variations between products (even products of a same batch) ?

2) is it safe to submit "permanently" a DRV5056 to a negative magnetic flux ?

Thanks

  • 0
    TI__Prodigy 305 points

    Hello Vincent,

      Thank you for posting to the E2E forum. The DRV5056 is not a bipolar device, so you may have experienced the .12 V voltage due to the South side of the magnet, if you apply the North side of the magnet yes you can go below the .6 V range, but this will not achieve anything on the datasheet as we only have guaranteed results within the linear region with a South Pole magnet.

    To further answer your questions:
    1)  If you place two magnets (one strong and the other weak) with the magnetic fields opposing each other, you will get a Ratio metric reading of the sum of the fields. For example if Magnet A, which in this case is a stronger Magnet than B, is facing the device with its south pole, and Magnet B, the weaker magnet is facing the device with its north pole, you should get a reading that's proportional to the difference of the magnets flux.

    2) It is safe as it will have no effect, you will just be in the non-linear region, but if you are using these types of magnet then it will have temporary effect, see quotation below:
    "The component must not contain ferromagnetic materials such as iron, nickel, and cobalt because these materials change the magnetic flux density at the sensor." (DRV5056 Datasheet, pg 17)

     Please let me know if you have further questions!
    Nikola