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MSP430FR5989: Confirm the layout guide line for VQFN package.

Kaka
Guru 24520 points
Part Number: MSP430FR5989

Hi TI Experts,

Please let me confirm the following question.
[Question]
According to the data sheet, there are some thermal pad and via under the device.
Do we must follow this layout guide line?
We will mount the connector in back layer. So, it is difficult for us to follow this request.

If you have any questions, please let me know.
Best regards.
Kaka

  • 0
    Guru 74080 points
    Hi Kaka!

    The pad recommendations at the end of the datasheet are for the packages in general - in your case for the RGC package. It shows 25 vias in the thermal pad. The MSP430 is a very low power device - the datasheet lists typically 100µA/MHz, so when running the device at 16MHz you would expect a current draw of 1.6mA - multiplied by the maximum allowed supply voltage of 3.6V, the device will have a power dissipation of about 5.8mW under these conditions.

    I don't see a requirement for all the vias - I don't even think you would need a single one. For the MSP430, this pad is more for mechanical stability, so if you cannot place some vias because of components on the other side, I wouldn't have any concerns without them.

    I have designs with and without vias, depending on the layout.

    Dennis
  • 0 in reply to Dennis Eichmann
    Guru 24520 points
    Hi Dennis,

    Thank you for your advice.
    I got it.

    Best regards.
    Kaka

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