Hi Sir,
My customer using TPS23754 12V2.5A design follow (slvu304c).
We have EMI issue in 30M~50MHZ(no load).
Do you have comments what we can do?
Another, L3 can be change inductor value?
We also try using the same inductor value but lower DCR can improve EMI but not enough.
Thanks, Ian.
Hello Ian,
This is very high frequency noise, much much higher than the switching frequency of the IC.
One of the factors for EMI is common mode current. Increase the common mode caps to help. Removing them would also help, but it would make the design susceptible to surge damage.
One of the biggest factors is layout. If they can use an EMI sniffer to try to determine which sections of the boards is radiating the most. Please have the customer review this EMI Guideline: 
Another method is to use / increase the EMI choke or ferrite beads. Both can be used in series.
Something else that is important to understand is the test setup is everything .
Lastly, understand this topology has four switching FETs, so overall EMI performance will be more difficult. You could try to add snubbers to the FETs to reduce ringing on the drains.
If this post answers your question, please indicate so by marking this thread as resolved. Thank you.
Regards,
Michael P.
Applications Engineer
Texas Instruments
Hi Michael,
Thanks for information.
For FETs to reduce ringing is where as below 4 circles?
Thanks, Ian.
