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DRV425: Sensitive Area of the DRV 425

Rodmehr Semnani
Prodigy 20 points
Part Number: DRV425

Hi there. I have DRV425 chips reading magnetic fields of magnets about 1/16 the size of the chip. There is a small arrow on the top of the chip indicating what I believe to be the most sensitive region and also the direction of sensitivity. I have to make a 3D model with the magnet placed directly over the chip, however, I do not have the exact dimensions of the chip nor the exact measurements of where the sensitive regions are on the chip. Unfortunately, the data sheet doesn't have this information either.

If I could get help with finding the exact dimensions and regions of sensitivity on the chip, that would be wonderful!

Thanks!

  • 0
    TI__Mastermind 20980 points
    Hi Rodmehr,

    I've reached out to Javier, who should follow up with you shortly.

    Carolus
  • 0
    TI__Mastermind 31050 points

    Hello Rodmehr,

    I have attached a picture that may help you with the sensor location.  These number are typical.  If you have need for greater accuracy than  +/-1mil (+/-0.0254mm)  please let me know your application as I would not assume the magnetic field will change much in the variation of these numbers.

    Thanks,

    Javier Contreras

  • 0 in reply to Javier Contreras4
    Prodigy 20 points

    Hi there,

    Thanks for your quick reply and the information. Looking at the figure, I see that there's ~400microns of space between the sensor and the top of the chip. I was wondering if it would be possible to have the chips ground down to where the sensor had next to nothing above it.
    Thanks!
  • 0 in reply to Rodmehr Semnani
    TI__Mastermind 31050 points

    Hi Rodmehr,

    Sorry for the delayed reply.  I guess I do not understand how you would like to use the device and what is if you will be trying to ultimately measure.  The magnetic field will be measured produced any magnetic source.  The currents from traces could produce a magnetic field but depending on your measurement and the layout they could be insignificant.  You can use the equation below to calculate the magnetic field.  Where I is the current and R is the distance from the current.  Now keep in mind the direction of the current matters as the DRV425 is sensitive in only one axis.  Please let me know if I am not understanding your concern. 

    B = [u0 *I ] / [2(Pi)*R)]

    u0 = 4*Pi  * 10^-7

    Regards,

    Javier

  • 0 in reply to Javier Contreras4
    Prodigy 10 points
    Hi Javier,

    I have a similar problem: I want to measure the magnetic flux in a (almost) closed magnetic circuit, and in order to keep it closed I need to bring the sensor of the DRV425 in direct contact with the rest of the circuit, since additional air gaps would change the flux. Is there a reliable way to do this?

    Regards,
    Rudi
  • 0 in reply to Rudi Mann
    TI__Mastermind 31050 points

    Rudi,

    Is there any way that you could provide a drawing of what you are measuring and the air gaps you are talking about?  I think it would be much clearer if I could see a drawing to give you the best recommendations.  If you would not like to post on the forum please email me. j-contreras@ti.com.