TPS62130 EMI and snubbers

Denis Alain1

Other Parts Discussed in Thread: TPS62130, TPS62085, TPS62090

Hi,

We want to design a new system with a **plastic box** (no EMI shield). This system will have 6x TPS62130 DC-DCs. The input voltage is 5V and all outputs varies from 3.3V downto 1V. We are talking about 0.5A to 2A.

I'm worry about the EMI caused by the ringing on the output SW / LC node. In the past, I used a lot of snubber circuits avoid that (RC). Now, it seems not recommended for most buck DC-DCs from TI.

Should I add snubbers to my design or try without it. I look at the EVM and the layout seems perfect for me. Adding a snubber may cause layout problem and increase ringings.

Also, the EVM does not provide a lot of ringing with 1,7A load. However, the ringing freq are around 280MHz.

Thanks,
Denis

over 10 years ago

0 Chris Glaser over 10 years ago

TI__Guru**** 150950 points

If you just have a 5V input, the TPS62085 offers a smaller solution which is optimized for the lower input voltage.

Yes, snubbers, etc. are not required but may be needed depending on the application. You could build a PCB with the snubbers there and just not populate the components.

The other main way to reduce EMI issues is a small sized input cap located as close to the device as possible. In some applications, we've seen around a 330pF capacitor have a self-resonant frequency at around the peak of the EMI radiated. So, it cancels this well.

If these are needed is entirely application dependent.

0 Denis Alain1 over 10 years ago in reply to Chris Glaser

Intellectual 600 points

Ok, thanks for the answer. The TPS62085 is interesting, but I need to control SS.

I will add the small input cap in case of. I will try to have a very good layout and avoid snubbers. We will see!

Regards,

Denis

0 Chris Glaser over 10 years ago in reply to Denis Alain1

TI__Guru**** 150950 points

If you need SS, there is TPS62090 which is optimized for a 5V input.

0 Denis Alain1 over 10 years ago in reply to Chris Glaser

Intellectual 600 points

Ok, thanks. The announced efficiency is awesome!

TI has a lot of DC-DCs. I didn't find that one.

Best Regards,

Denis

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TPS62130 EMI and snubbers