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TPS54429E: TPS54429E QFN16 layout guidance

Craig Easdale
Expert 2170 points
Part Number: TPS54429E
Other Parts Discussed in Thread: TPS54526

I've decided to use a couple of TPS54429E buck converters in a new design and I just wanted to get some guidance on my layout since I've use the QFN part which does not have a recommended layout shown in the datasheet. The schematic and layout are shown below, I've got the 12V power coming in from the bottom, and 5V exiting at the top. I plan to use the same part for a 3v3 rail, and will likely use an identical layout but with different values for some components.

I'd really appreciate if someone could have a look at my layout and let me know if it is going to be adequate. I've done my best to folow the layout guidelines, but could do with a sense-check to make sure I've not missed anythnig significant in this first draft. The PCB will be 4 layers, with a ground plane directly below the top layer.

Thanks.

  • 0
    TI__Mastermind 24180 points

    Hi Craig,

    Let me take a look and get back to you by tomorrow.

    Thanks,

    Amod

  • 0
    TI__Mastermind 24180 points

    Hi Craig,

    Sorry for the inconvenience of not having a reference TPS54429E QFN layout in the datasheet. Please refer to TPS54526 page 20 for this layout. It is identical pinout and package so that should work. 

    Some comments:

    1. C17 should be directly connected to VREG5. Please note C17 should not be connected to PG as shown in schematic.

    2. R10 is not required.

    3. I would follow TPS54526 layout as closely as possible:

    • L2 should be rotated 180deg, move C84, C103 to near PGND pins
    • Rotate input cap C2/C10/C11 90deg, connect GND copper same as TPS54526
    • Change all the capacitors and IC GND pad or pin connection from thermal relief to solid connection
    • Move Vo via from inductor pad to output caps pad.
    • Add 9 thermal vias on IC thermal pad

    Thanks,

    Amod