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DRV5032: DRV5032FD

Noe Martinez
Prodigy 10 points
Part Number: DRV5032

We are using a North facing magnet inside pump head to be able to detect the rotation speed(RPM). The magnet sits12.5mm away from the DRV5032FDDMR when it passes on top of it.  The magnet is spec to have a min of 55mT(We dont have the specifics of the magnet).  When we see the output of the DRV5032, we see the it is inverted. Is low for about 50 to 100mS and then high. The datasheet states that this is possible  

When the applied magnetic flux density exceeds the BOP
threshold, the device outputs a low voltage. The
output stays low until the flux density decreases to
less than BRP, and then the output either drives a
high voltage or becomes high impedance, depending
on the device version.

What is not understood is whether this is OK  to have. We recently just started seeing that the device misses pulses and our system faults when this happens.  If this is not advisable, any idea what needs to change to make this work reliably.

Thank you for your help.

  • 0
    TI__Mastermind 26335 points

    Hello Noe,

    Thanks for considering to use Texas Instruments.  Is the 55mT spec for a point 12.5mm away from the magnet or at the surface of the magnet?  If that spec corresponds to the strength at the magnet surface, its possible the field seen by the device is weak and any wobble or vibration during the rotation could result in a momentary spacing increase where the device and magnet are spaced too far apart. Another possibility is that the magnet is not passing over the device during the sampling window.  The DRV5032 is not always active.  If the magnet passes over the device while it is inactive, then its always going to output high and alternatively if the magnet passes right at each tactive pulse, then the output is going to remain low. 

    To better diagnose your issue, it will help if you can provide a diagram of what you are doing with the sensor and magnet along with the rotation speed.  Dimensions and magnet grade are helpful for us to determine if the magnet is strong enough per the placement in your design.  If you are uncomfortable with sharing that in this public forum, you can either assess that with our TIMSS tool here, or you could share that with me through a private message.

  • 0 in reply to Patrick Simmons
    Prodigy 10 points

    Hi Patrick,

    I prefer to share with you privately. How do I do that?

    Noe

  • 0 in reply to Noe Martinez
    TI__Mastermind 26335 points

    Hello Noe,

    Not sure if you have the option on your end, but if I click on your name to look at your profile I am given the option to connect.  After a connection has been accepted you should be able to send private messages.  To send a private message you can click the dialogue icon near the top right of the e2e webpage.  I just sent you a message, so if you go there you should be able to respond.