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TMAG5170: TMAG5170 layout

Milos Jesic
Prodigy 50 points
Part Number: TMAG5170

Tool/software:

Hello,

I'm curious if you have any layout recommendation for TMAG5170? Usually, magnetic encoders need a copper keepout under the body so that the magnetic field can go through and close the loop. I don't see any recommendation in the data sheet. I'm curious if it's okay to route traces under the IC?

I see that you routed traces and you have vias under the body of the IC so not sure if that will create any issue. 

  • 0
    TI__Mastermind 21130 points

    Milos,

    Copper is a weak diamagnetic material, and in most cases you won't notice significant impact from a ground pour or incidental trace.  In the presence of a strong magnetic field which is changing rapidly, it can interact with the field in such a way to resist the motion of the magnet.  There are some interesting videos you can find on this on the internet.  Recently I attempted to check if I would see any difference using this device and passing a PCB with copper pours between the sensor and didn't notice any significant shift in the magnetic field observed by the sensor. You should observe in low speed or static situations that the field permeates through the copper.

    However, if you are concerned, it certainly does not hurt to route around and place a keep out under the sensor.  For this particular board, there was a need to keep the size of the paddle to a minimum, and this necessitated the routing as shown.

    Thanks,

    Scott