TPS62130: layout consideration about TPS62130's AGND, PGND and EP

Zhengyun

Part Number: TPS62130
Other Parts Discussed in Thread: TPS62135

Hi,

I’m using TI’s DC/DC TPS62130, and have read the paper “Five steps to a great PCB layout for a step-down converter”, in which the idea that handle high-current part and small signal part separately helps me a lot for layout. Now I have a question about the final connection about AGND, PGND and EP-GND:

Can I keep the AGND, EP-GND, PGND clear of each other, on the top plane(main routing plane for the DC/DC chip), and just connect them to the GND plane by independent vias? but doing this, basically they share the same voltage base line and thus the internal circuit of tps62130 can work normally; secondly the AGND return path and PGND return path will un-likely infer each other. (less spike coupled into the small signal circuit in AGND domain?). Could anyone help to check my thought and give any advice?

thanks!

Zhengyun Liu

over 7 years ago

0 Chris Glaser over 7 years ago

TI__Guru**** 150820 points

Hi Zhengyun,

Thank you for reading my paper.

If I understand your idea correctly, to separate the GNDs on the top layer, then this type of connection is prohibited in the D/S (on page 4 for example). These GNDs should tie together with the least impedance between them to reduce any GND shifts that could occur due to the switching currents.

As well, we have the newer, smaller, more accurate, higher current TPS62135/6 as an improvement over the TPS62130.

0 Zhengyun over 7 years ago in reply to Chris Glaser

Prodigy 50 points

Hi, Chris,

Thanks, I see the GND's requirement in the D/S. So even if the 3 types of GND are connected to the common GND plane, e.g, in the 2nd layer, it is better to tie them together in the EP-PAD on the top layer?

Zhengyun

0 Chris Glaser over 7 years ago in reply to Zhengyun

TI__Guru**** 150820 points

Yes, it is better and required to tie them on the top copper layer. This gives a lower impedance by not going through vias to make the connection.

0 Zhengyun over 7 years ago in reply to Chris Glaser

Prodigy 50 points

Thanks for your explanation and recommendation for better performance chips!

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TPS62130: layout consideration about TPS62130's AGND, PGND and EP