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TMS320F28377D: Use TI created PCB footprint or create footprint from datasheet

Liet Ly
Prodigy 20 points
Part Number: TMS320F28377D

To Whom It May Concern:

I have a project which use TMS320F28377DPTPS dsp.

I downloaded the CAD/CAE PCB footprint for use with Cadence OrCAD PCB Editor 17.2.

However, when comparing the downloaded footprints with the datasheet for TMS320F28377DPTPS, the dimensions don't match exactly.

What do you suggest is the correct option:  use the downloaded footprint or created base on the datasheet?

Thanks,

Liet L.

  • 0
    TI__Expert 8105 points

    Hi Liet,

    When having conflicting docs, you should always go by the datasheet. But in this case the datasheet should match the footprint exactly. Did you use the .bxl file from the product folder to generate the footprint? could you send a screenshot of the portion of the footprint that doesn't match the datasheet?

    Regards,

    Peter

  • 0 in reply to Peter Galicki
    Prodigy 20 points

    Hi Peter,

    Attached is the screenshot of the footprint.

    The shape of the peripheral pins look different than the datasheet, and the thermal relief/GND vias are different in quantity and locations.

    Thanks,

    Liet Ly

  • 0 in reply to Liet Ly
    TI__Expert 8105 points

    Hi Liet,

    I do not see your attachment, but I now think I understand your thermal pad concern. The datasheet shows the thermal pad under the device. The .bxl file has the pcb footprint onto which the device will be soldered. The thermal pad of the footprint is typically bigger than the device pad in order to carry more heat. The suggested footprint pad is the best case pad that carries most heat away from the device. But typically that actual size of the footprint pad can be smaller depending on many factors, for example number of ground planes, ambient temperature, airflow over the board and how much room under the device is needed for signal routing and placement of decoupling capacitors. See chapter 2.3 in the attached document for additional information on this.

    Regards,
    PEter

    1072.hwg_16c.pdf