TPS54240: Snubber Circuit to reduce EMI

Nathan Gartner

Part Number: TPS54240

Hello,

I utilized the TPS2511EVM-141 components and layout in a design with a BLE connected device and the Circuit is failing radio emissions testing due to EMI created by the switching regulator, TPS54240.

We have high frequency ringing around 180MHz.

I would like to know if there are any recommendations for a snubber circuit or any kind of filtering for use with the components and respective values in on the EVM board that will effectively reduce ringing on the output of the TPS54240 and minimize EMI so we can pass our EMC testing

See attached Data sheet, schematic on PG 4.5516.TPS2511EVM-141.userGuide.pdf

Thank you

over 5 years ago

0 Andy Chen over 5 years ago

TI__Mastermind 34875 points

Hi Nathan,

Did you mean the circuit pass CE and failed RE test at 180MHz? do you have chance to upgrade the design with TI latest converter which has better EMI performance?

You try something below on present circuit:

1. add 4.7--22 ohm in series with BOOT cap

2. Add snubber on PH pin----refer to Application note: https://www.ti.com/lit/an/slua831a/slua831a.pdf SLUA831A

B R

Andy

0 Nathan Gartner over 5 years ago in reply to Andy Chen

Prodigy 60 points

Thank you for the reply Andy,

1. I will modify and test this

2. I have added a snubber cicuit on the PH Pin and noticed a reduction in frequency from 180MHz to 42MHz.

How can I tell if the part I am using is the latest converter from TI? I am using:

TPS54240DGQR

Thank you.

Nathan

0 Andy Chen over 5 years ago in reply to Nathan Gartner

TI__Mastermind 34875 points

Hi Nathan,

Pls check latest LMR63625 which has much better EMI performance.

B R

Andy

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TPS54240: Snubber Circuit to reduce EMI