LM46001-Q1: Conducted emission at 500KHz not able to supress

Vinayak Aghor

Part Number: LM46001-Q1

Hello,

We use LM46001-Q1 for 24 to 12V conversion @ current 500mA. SW FRQ is 500KHz. In conducted emission testing we are getting peak @ 49dBuV. This we are not able to suppress at any combination of CLC filter at input side regulator. Kindly help on this. At present we are using 22uF - 10uH - 22uF filter. we want to suppress emission below 20dBuV.

Regards,

Vinayak

over 7 years ago

0 Frank De Stasi over 7 years ago

TI__Guru 74215 points

Can you share your schematic and layout.

0 Vinayak Aghor over 7 years ago in reply to Frank De Stasi

Prodigy 130 points

Hello Frank,

Here I am attaching sch & layout of power section.

Here, with above schematic & C14 replaced by ceramic capacitors, we completely removed emission of 5V regulator. But, we could not suppress emission from 12 V regulator.

0 Vinayak Aghor over 7 years ago in reply to Vinayak Aghor

Prodigy 130 points

Hello,
If we add 39uF - 6.8uH - 22uF filter in front of above schematic then all emissions are suppressed. But we cant change PCB layout. Please suggest suitable filter in above schematic it self.

Regards,
Vinayak

0 Frank De Stasi over 7 years ago in reply to Vinayak Aghor

TI__Guru 74215 points

I would try the same components on the 12V reg and see if that helps.

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LM46001-Q1: Conducted emission at 500KHz not able to supress