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TPSM365R3: TPSM365 recommended layout

Quaternion Aerospace
Prodigy 20 points
Part Number: TPSM365R3

Tool/software:

Hello, 

I am using the TPSM365R3 switching regulator to supply 5V from my 50.4V PACK+ input on my PCB. The recommended layout from https://www.ti.com/lit/ds/symlink/tpsm365r3.pdf?ts=1695280710728&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPSM365R3 on page 44 appears to be using fencing vias around the regulator. Are these fencing vias to reduce effects of EMI from the regulator to the rest of the board and if so are there any recommendation on where/how to place these. 

Thanks,

Fritz Schnackenpfefferhausen

  • 0
    TI__Genius 9170 points

    Hello Fritz,

    Yes it is a common practice to place shielding vias, typically the shielding vias are placed at the input and output traces of the converter.  Shielding vias create a barrier for high-frequency switching noise. The input and output traces carry high-frequency ripple currents, which can act as miniature antennas and radiate EMI. They also provide a low impedance ground return for high frequency currents, allowing for the noise to be mitigated. 

    A larger picture of the vias can be found in the EVM:

    Regards, 

    Oscar Ambriz 

  • 0 in reply to Oscar Ambriz
    Prodigy 20 points

    Hello Mr. Oscar,

    I appreciate your response to my query and have taken it under advisement. Is there any recommended spacing between vias in the fencing? From my limited understanding there is a relation between the switching frequency (wavelength) and spacing, but of this I am not sure. 

    This is the current layout I have Mr. Oscar, would you be so kind to advise if following as appropriate. I have tried to follow my very best the recommended layout. 


    Thank you,

    Fritz

  • 0 in reply to Quaternion Aerospace
    TI__Genius 9170 points

    Hello Fritz

    If possible it would be good to have the vias wrap around the Vout trace as i have shown below in the figure in blue pen, we just want to make sure that the noise coming from the switch node doesn't make it the vout. This would mean moving the caps a bit to the left to make room, or having smaller vias. A tighter vias switch would also be recommended. 

  • 0 in reply to Oscar Ambriz
    Prodigy 20 points

    Hello again Mr Oscar.

    I will take your advice under advisement, you are very helpful and I greatly appreciate the support with this design. 
    Please have yourself the most wonderful day possible. 

    Regards,

    Fritz