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TIDA-00701: Layout of input/primary traces on reference power supply design

ajh
Prodigy 30 points
Part Number: TIDA-00701

I have a question about the shape of the PCB traces in TI's reference design for the TIDA-00701 power supply. On the input/primary side, the traces are very chunky copper fills instead of linear traces directly between the pads. Is there an engineering reason for the shape of the traces? I recognize that necking down around certain pads is likely for thermal relief during soldering, but I'm trying to understand the reason for the oversized geometry elsewhere--the current capacity will be limited by the smallest cross section. Will there be any performance issues using straight linear traces? I've attached an annotated copy of one of the Gerber files showing the traces I'm referring to. Thank you for the help.

  • 0
    TI__Intellectual 940 points

    For the layout, you need to pay attention to below items:

    1. the trace should have enough current capacity.

    2. the distance between the traces should meet pressure requirement.

    the layout in the picture is common and different designer has his own habit.

  • 0 in reply to Huixin Wang
    Prodigy 30 points

    Thank you for the response. I understand the impact of current and voltage requirements in PCB trace design, but this didn't really answer my question about the unusual shape of the traces in this specific design. Why does this design use oversized copper fills between some of the pads? It seems that straight traces of uniform size would accomplish the same thing, especially for the power requirements of this board. Is the extra copper for thermal reasons, mechanical reasons, etc.? Please see below:

  • 0 in reply to ajh
    TI__Intellectual 940 points

    As I replied before, you need to pay attention to these two items. Others are not related to your layout.

    Oversize copper is intend to increase current capability and reduce the impedance. The trace around the pad is narrow which can make the capacitor/inductor play a better role of filter. Also there are some habits of the designer when he did the layout.

     

  • 0 in reply to Huixin Wang
    Prodigy 30 points

    Thanks for clarifying--I appreciate your reply back!