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TPS62150 EMC

Will Haylock
Prodigy 190 points
Other Parts Discussed in Thread: TPS62150

We use the TPS62150 in several of our products and are very happy with its performance - however when EMC testing my latest design I noticed that there is some broadband EMI generated by the TPS62150 circuit in the 360MHz region.

The layout follows all the good principles specified in your application notes, specifically we have minimised the 'hot loop' to as small as the components allow - we are using a non shielded 2u2 inductor and running at 2.5MHz, the output voltage is 3.3V and the output current 150mA.

Would you expect EMI in this frequency range? Can you suggest anyway that I can reduce this?

  • 0
    TI__Guru*** 148780 points
    Yes, all SMPS make EMI somewhere in the spectrum. On most devices, it is the rising edge of the SW node which creates the EMI at that high of a frequency. If this is not mitigated by your system design (enclosure, etc.) then you can mitigate it at the component level.

    AN RC snubber on the SW node is one method.

    The other method is to add another input cap closest to the device. This input cap would be in the smallest case size you are allowed to use to keep its ESL down. Pick the value whose self-resonant frequency is at the frequency of your EMC. If I remember correctly, around a 470pF cap gave this.
  • 0 in reply to Chris Glaser
    Prodigy 190 points

    Thank you - that has answered my question, I will experiment with the capacitor and snubber network.