TPS54386-Q1: The EMI performance

Aggil

Generally it is not advisable to introduce inductance or capacitance in between grounds.  I recommend you use zero ohm inductors.  As to your  EMI issues, it is important to know the fundamental frequencies as well as the harmonics that are causing you to fail.  I cannot tell the from your bit map images.  Can you tell me the peak values?  Also we will need to see your PCB layout..

Hi John

  thank you for the respond. Attach another result for your referance. We will supply the PCB layout file latter. 

Aggil,

The 240 MHz and 144 MHz peaks are likely harmonics of the 600 kHz switching frequency.  The others are probably not.  Can I see a waveform of the switching node for both channels?  I need you to measure the cat switching frequencies. Also Zoom in and capture the rising and falling edge and observe the frequencies of any ringing.

Enclosed the PCB file.

AG018V15.zip

Hi John;

   Could you tell me this device can be compliant with CISPR25 Class 4 conducted emissions.Thanks.

In addition,we use TPS57140QDGQRQ1 together.

Hi John；

    Could you tell me this devices can be compliant with CISPR25 Class 5 conducted emissions? Thanks.

In additon,we use TPS57140Q together.