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LMG3410R070: LMG3410-Thermal Via

Intellectual 980 points

Replies: 6

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Part Number: LMG3410R070

Hello

We are studying TIDA-00915 as a reference design to use LMG3410 in designing an inverter....we found that if we use 66 thermal via (10 mil each) we end of very small heat-sink....our question is why did not reference design do that? ie why did not they reduce the heat sink size?

Regards

Sam

  • Hi Sam,

    Yes you could add more vias. This TIDA is mainly to demonstrate to you regarding the application in motor drive for certain power level. If you prefer to add more thermal vias, yes it will help reduce the thermal resistance and finally the heat sink size. You can also refer to our half bridge LMG3410-HB-EVM for more guidance regarding the details of laying out a half-bridge.

    Thanks and regards,

    Lixing

  • In reply to Lixing Fu:

    Hi Lixing
    Thank you.

    Have you used LMG3410 (or any LMG) before?

    What the side effect or drawback of using more thermal vias?

    Regards
    Sam
  • In reply to Sam Ref:

    Hi Sam,

    Currently I am a system engineer covering TI's GaN products. So yes, I have used and am very familiar with all the LMG parts.

    Typically we recommend more thermal vias if possible to be placed below the device to help thermal conduction. We have not seen drawbacks except the cost. However, it is critical that you layout the return path below part of the IC to help reduce parasitic inductance. This could occupy some area that you can populate more thermal vias.

    Thanks and regards,
    Lixing
  • In reply to Lixing Fu:

    Hi Lixing

    Can you please explain to us what is the return path?

    Regards

    Sam

  • In reply to Sam Ref:

    Sam, 

    The return path is typically laid out through the bottom of the device to achieve the smallest parasitic inductance. Therefore, if your return path is the ground, the high side device ground which is switching node should have some clearance to the path, and should have less thermal vias. To understand it better, I would recommend you look into  LMG3410-HB-EVM for more information. When you take a look into the layout, you will find out.

    Thanks and regards,

    Lixing

  • In reply to Lixing Fu:

    Thank you Lixing

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