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LMR33630: LMR33630 layout issue

Eric Shen42
Expert 2750 points
Part Number: LMR33630

Dear TI:
    I check the datasheet layout guide, there are GND layout under the inductor.

    My problem is someone suggest laying GND under the inductor, someone suggest not laying the GND. What kind of advice is reasonable and why?

    Thanks!

Regards!

Eric Shen

   

  • 0
    TI__Mastermind 25590 points
    Eric,

    The GND under the inductor will capacitively couple to the SW node. This has two main effects:

    1. Current injects into the GND plane which may corrupt regulation through "ground bounce".

    2. SW capacitive coupling is shielded by the GND plane which reduces common-mode noise in EMI measurements.

    I don't expect 1 will be a huge issue with this part so you should have no issues placing a GND plane under the IC, plus you get better EMI performance.

    -Sam
  • 0 in reply to Samuel Jaffe
    Expert 2750 points

    Hi Sam:

        Thanks a lot!

    Regards!

    Eric