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LMR14020: EMI problem for help

Stanley Xu
Intellectual 1300 points
Part Number: LMR14020

Hi engineers，

There is a EMI problem from customer which occur in a 12V to 5V step-down application based on LMR14020, this circuit works fine.

Background:

they encountered an EMI problem that 3dB exceed  at the 330KHZ frequency point(Disconnect load) and they are currently in small batch production,  So PCB layout are fixed.

Question:

1.Are there any ways to improve EMI performance without changing the layout ?

2.If they are willing to modify PCB layout, what needs to be modified in their current layout and why?

The test results show as below：

the schematic diagram show as below：

The PCB layout show as below：

  • 0
    TI__Expert 3490 points

    Hi Stanley,

    1. Optimized EMI filter design attenuates conducted EMI, as shown in this app note.

    You can also test the SW node voltage and do some bom change to the RC snubber to reduce high frequency spike to improve EMI performance.

    2. Please kindly check whether customer's layout follows the layout guideline in datasheet section 11.1 Layout Guidelines.

    Regards,

    Xiaoying