LMR50410: LMR50410_ noise problem

Shashank Varshney

Part Number: LMR50410

Hello ,

I am using LMR50410YQDBVRQ1 buck converter in my design for 24v to 12v conversion. The inductor used in my design is of 33uH. It is radiating noise and the whole board is failing in RE test.

I have attached the circuit diagram . I am also attaching the noise radiated and captured by Near field probe. Please can anyone help.

I also captured the switching across the inductor which has some ringing.

over 4 years ago

0 Frank De Stasi over 4 years ago

TI__Guru 71985 points

Hello

I can see your schematic but I don't see your scope plots or EMI results.

Also, we will need a view of your PCB layout.

Do you have an EMI filter??

Are you using a shielded inductor??

What EMI specifications are you trying to pass??

Thanks

0 Shashank Varshney over 4 years ago in reply to Frank De Stasi

Prodigy 10 points

Hello Frank,

Thanks for the reply. Hope you are doing good. Yes we are using a shielded inductor of 33uH (LPS6235-333MRB) from Coil craft.

No we don't have any EMI Filter . we are trying to pass RE for the whole system.

0 Frank De Stasi over 4 years ago in reply to Shashank Varshney

TI__Guru 71985 points

Hello

It does help to have an EMI filter even for RE.

What EMI specification are you trying to pass??

How far above the limit are you??

Thanks

0 Shashank Varshney over 4 years ago in reply to Frank De Stasi

Prodigy 10 points

hello frank,

We are trying to pass Class A 40db(30Mhz to 230MHz).

We are just matching the limit . But we need to pass the limit by 4db atleast.

0 Frank De Stasi over 4 years ago in reply to Shashank Varshney

TI__Guru 71985 points

Hello

Can you show us your PVB layout. Simple images would be good.

What frequency are you failing??

Thanks

0 Frank De Stasi over 4 years ago in reply to Frank De Stasi

TI__Guru 71985 points

Hello

I will close this post due to inactivity.

Thanks

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LMR50410: LMR50410_ noise problem