TPS922052: TPS922052/3 EMC problems

DHortelano

Part Number: TPS922052
Other Parts Discussed in Thread: TPS922053

Tool/software:

Hi all,

We have developed a electronic pcb with the TPS922052. We have tested TPS922052 and TPS922053 but we have problems with the radiated emitions.

Our buck have to convert 48V to 42V output with 600mA output current.

You can see the schematic with the snubber filter in te following image.

On the other hand, you can see our pcb layout in the following image.

You can see the results we have for conducted in the following image:

You can see the results we have for radiated in the following image:

Could someone help me? I think the buck layout is good. Is the snubber network correctly placed in the schematic?

Thank you in advanced,

David.

5 months ago

0 Lucia Gao 5 months ago

TI__Mastermind 30471 points

Dear David,

Pls kindly let me check your questions and get back to you during these days. Thank you!

BRs

Lucia

0 Lucia Gao 5 months ago in reply to Lucia Gao

TI__Mastermind 30471 points

Dear David,

Could you pls kindly check below ways to help improve radiation emissions?

1. Add RC snubber Power Tips: Calculate an R-C snubber in seven steps

2. Add EMI filter in the input side.

3.Add Ferrite bead in the output side.

4.Add shielding case.

Thank you!

BRs

Lucia

0 DHortelano 5 months ago

Prodigy 10 points

Hi Lucia,

1. Add RC snubber. We have RC snubber with R14 - R15 - C23 as you can see at image 1.

2. Add EMI filter in the input side. We have LC filter with 47uH and two parallel 4.7uF capacitors.

3.Add Ferrite bead in the output side. We can try it, we have the footprint.

4.Add shielding case. It's imposible because is a plastic case and we can't change it.

I put the RC snubber filter on the switch pin, is that correct? Have you checked the layout?

Thank you Lucia

0 Lucia Gao 5 months ago in reply to DHortelano

TI__Mastermind 30471 points

Dear Sir,

I begin to review the layout and I will get back to you soon. Thank you!

BRs

Lucia

0 Lucia Gao 5 months ago in reply to Lucia Gao

TI__Mastermind 30471 points

Dear David,

The layout is good from my side. Thank you!

BRs

Lucia

0 DHortelano 5 months ago in reply to Lucia Gao

Prodigy 10 points

Ok, thank you

But what about the RC snnuber? Is it placed correctly in the schematic?

0 Patrick Yao 5 months ago in reply to DHortelano

TI__Mastermind 34780 points

Hi David,

Our expert will give you feedback later.

0 Lucia Gao 4 months ago in reply to DHortelano

TI__Mastermind 30471 points

Dear David,

We would recommend to place the RC snubber as shown below: (You can refer to User's guide) R2, R6 and C16

Thank you!

BRs

Lucia

0 DHortelano 4 months ago in reply to Lucia Gao

Prodigy 10 points

Dear Lucia,

We have analyzed your RC snubber proposal and we find it interesting. We will develop a prototype with all the suggestions, and two months later we think we can revisit the topic to share the results. Thank you for your support!

0 Lucia Gao 4 months ago in reply to DHortelano

TI__Mastermind 30471 points

Dear David,

Your welcome. Feel free to let us know if any further support need. Thank you!

BRs

Lucia

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TPS922052: TPS922052/3 EMC problems