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TPS61196: About EMI Radiation improvement

Prodigy 60 points

Replies: 5

Views: 49

Part Number: TPS61196

Hi Sir,

When TPS61196 drives the LED strings, the EMI radiation test result will over 1.53dB@148.74MHz(as below Figure).

Please recommend how can I do to reduce the value of EMI radiation under 40dB on the schematic.

thank you!

Best Regard

Terry

  • Hi Terry,

    1. The input loop area (including inductor) and output loop area (including diode) should be as small as possible.

    2. The switching node size should be as small as possible.

    3. Adding via to SW is not recommended.

    BR,

    Robin

  • In reply to Yuting Shao:

    Hi Robin,

    Thanks for your kind reply. But we can't modify PCB layout because of the customer's schedule.

    Could you please recommend how to adjust the specification of components (like capacitor or resistor...etc.) to reduce EMI radiation?

    Thank you!

    Best Regard

    Terry

  • In reply to Terry Tai:

    Hi Terry,

    Adjusting the resister and capacitor of MOSFET gate could configure the slew rate. Slower rate is helpful to reduce EMI radiation.

    BR,

    Robin

  • In reply to Yuting Shao:

    Hi Robin,

    According to your recommend and chapter 8.2.2.3 of TPS61196's specification, it seems to mean R19 resistor.

    Should I adjust the resistor value to be above or below 3 Ohm? And, would this adjustment affect other functions? 

    Thank you!

    Best Regard

    Terry

  • In reply to Terry Tai:

    Hi Terry,

    Larger resister will improve EMI performance but increase switching power loss. 

    BR,

    Robin