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DRV5023: About Min/Max of sensor sensitivity

Tsukui Yusuke
Guru 21930 points
Part Number: DRV5023

Hi,

Customers want to specify Min/Max of sensor sensitivity in customer application.
Could you please tell me how to verify Min/Max recommended by TI with an actual device?
Customers are considering TI Hall sensors for the first time.
Therefore, Customer would like to know the procedure for verification and the evaluation method.

Could you give me your advice?

Best Regards
Yusuke

  • 0
    TI__Genius 16440 points

    Yusuke-san,

    In this device, the mode of operation is that in the no magnetic field input state the output will be high.  Once magnetic flux density increases beyond the operating point BOP, then the output will toggle low.  To prevent erroneous switching when the field is near the threshold, there is hysteresis built in around the release threshold.  That is, the magnetic flux density must return to levels below BRP in order for the output signal to return high.

    To test this with an actual device, you will need a magnet.  Typically, many of our EVMs are supplied with one.  It is worth noting here that various Hall sensors will either be uni-polar (sensitive to either a north or south pole, but not both), or omni-polar (sensitive to either pole).  When we refer to a positive B field value, this is representative of the magnetic flux directed upward through the bottom of the package as shown below.

    So, if we are expecting a positive B field to trip a uni-polar device, we would present the sensor with the south pole of the magnet.

    The device landing page for DRV5023 has a calculator tool which may help determine the distance to expect the device to toggle for various magnet types.  The calculator only is able to calculate distance based on the orientation shown above, with the sensor aligned with the axis of polarization.  Other orientations are possible, however, as long as the component of the field directed upward through the package will exceed BRP and BOP.  

    When considering BRP and BOP thresholds, it is recommended to design about the maximum range possible shown in the datasheet to ensure a robust solution across device tolerances.  For example, DRV5023FA has sensitivity as shown here

    In this case, the worst case maximum for BOP is 6.8 mT, and the worst case BRP is 0.5 mT.  For any given sensor, the typical difference between BOP and BRP will be about 1.5 mT, however.  In order to ensure all devices are tripped by the motion of the magnet, it would be necessary to ensure that the final position of the magnet exceed 6.8 mT, and the starting position of the magnet be below 0.5 mT.

    Thanks,

    Scott