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TPS82140: Radiated Emissions (EMC) issues.

Michael Kaluzny
Prodigy 10 points
Part Number: TPS82140

Hi, I got a Radiated Emissions scan of my new board which uses the TPS82140 and got poor results. The TPS82140 appears to be the noise generator.

Here is the scan results (H) only.

Here is a near field H probe scan above the TPS (note not Log scale on X)

Here is my layout

As far as I can tell my circuit and layout are following all the guidelines.

Any suggestions?

  • 0
    TI__Mastermind 45970 points

    Hi Michael,

    1. Could you please double check if TPS8210 is this noise culprit? Is there possible from other downstream or upstream parts? Generally the EVM performance of TPS82140 is better because the inductor and SW are no longer exposed which are the main sources of EMI.

    2. The radiated EVM performance is highly related to the PCB layout, But your input/out capacitors placement look good. Could you try to add a small HF ceramic bypass cap(0.1uF/0.47uF/0402) between Vin and GND close to pins. You can also add a 0.1uF between Vout to GND as well. If it is possible, could you send me the full layout file, I can review inner and GND layer. My email address: nancy_zhang@ti.com

    3. The most effective way is to add a pi filter at input and it will improve both conducted and radiated emission.

    Thanks,

    Nancy