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MSP432 breakout board PCB design

Antony Prasad
Prodigy 60 points

My first attempt to design a breakout PCB for MSP432 QFN MCU..

This is my design...

Let me know any mistakes in the design. Thanks...

  • 0
    Guru 74080 points

    Hi Antony!

    A schematic of your board might be helpful. Is the red marked part the DCDC converter?

    If so, the GND connection is very bad. There are a few strange looking connections:

    If you have GND at the TOP and on the BOTTOM, why are there traces connecting to TOP GND, but not to BOTTOM GND?

    Edit: I just realized you are having GND on TOP and 3.3V on BOTTOM. This makes it worse - you are connecting GND islands through long traces - look at Q2 at the upper right and GND underneath the processor, although this one is also connected at a few points on the TOP. I would have gone for GND on the BOTTOM.

    Dennis

  • 0 in reply to Dennis Eichmann
    Prodigy 60 points

    Here is the schematics...

    Yes, I have GND on top and bottom plane as 3.3V, just for easy routing for power... So you mean switching top as 3.3v and bottom as GND?

  • 0 in reply to Antony Prasad
    Guru 74080 points
    On a two layer board I would always go for a solid GND plane instead of a supply plane. Remember that you have bypassing capacitors at the supply pins, so power traces to the capacitors would be OK if there is no space for supply planes, but having GND as traces is never good. Since your components are on the TOP layer, GND would be better on the BOTTOM one. You can easily connect your GND pins of the TOP side components through the board to your GND plane. Furthermore you could think about some small GND islands for your two crystals in order to have the high frequency signals somehow isolated from your main GND area. The DCDC converter has quite high current spikes as well, of course. There are a few design guidelines in the web, just for some ideas of optimization.
  • 0 in reply to Dennis Eichmann
    Prodigy 60 points
    Thanks for your input Dennis,

    I will change bottom plane as GND, and do traces for 3.3V. I will check web for guidelines about DCDC converter thing and isolating GND for crystals...
  • 0 in reply to Antony Prasad
    Prodigy 60 points

    Here is the new updated design...

  • 0 in reply to Antony Prasad
    Prodigy 60 points

    This is better isolation with bottom GND connected through vias...

  • 0 in reply to Antony Prasad
    Guru 74080 points

    Hi Antony!

    With "GND islands" I did not mean islands free from GND - you should privide a GND plane to your crystal circuitry that is only connected to the main GND plane at a point at the microcontroller. That's why you usually have a GND connection right next to the crystal pins.

  • 0 in reply to Dennis Eichmann
    Prodigy 60 points

    Hope I did it right...

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