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TPS5450: EMI can't pass

Howard Zou
Genius 12365 points
Part Number: TPS5450

Hi, my customer is using TPS5450 for a 24V to 12V, 5A DC/DC.

The device can meet the function requirement. But no matter under heavy or light load, the EMI can't pass.

They test with battery as input, and resistor as load.

The schematic is as:

The test result is as

What may cause this problem and how to fix it?

thanks.

  • 0
    TI__Mastermind 25590 points

    Howard,

    Many things may cause EMI issues but I'll try to narrow it down with the info you've given.

    Try adding a 3-10 ohm resistor in series with Cboot. You can just lift one pad of the cap and add a resistor to make a little triangle like this. This will slow down the turn-on time of the high-side FET which will reduce ringing/overshoot. This ringing is usually in the few hundreds of MHz and will occur at every load.

    Please also share the layout. This is usually the main reason for poor EMI.

    -Sam