Layout Guide for POE design

Jay patel

Other Parts Discussed in Thread: TPS2378

Hi ,

I am designing a system board which will powered over Ethernet (UPOE).

I have a doubt in layout of Transformer. I am referring "TPS2378 EVM User’s Guide" for layout guidelines.

In this document it is suggested to provide solid ground between transformer's pads and also solid ground plane in below layers of transformer.

I also gone through generic POE layout guidelines from different companies. They recommends to avoid ground planes between transformer pads and below transformer.

Can you please suggest which is the best practice?

Thanks & Regards,

Jay Patel

over 9 years ago

0 Darwin Fernandez over 9 years ago

TI__Mastermind 41790 points

Hi Jay,

I recommend looking at the below to an app note on designing an EMI compliant PoE PD. This describes the laying out the power stage and the transformer considerations.

www.ti.com/.../technicaldocuments

0 Jay patel over 9 years ago in reply to Darwin Fernandez

Prodigy 160 points

Hi Dear,

Thank you very much for your response.

Yes i have gone through suggested app note. And in application note ground (BS ground) is provided surrounding to transformer and in below layer of transformer.

I am thinking that for SMPS due to high switching frequency it is recommended to avoid ground below transformer. But in our case for UPOE there will be no switching compared to SMPS so we can provide ground below transformer.

Please correct me and provide any other suggestion.

Thanks & Regards,

Jay Patel

0 Darwin Fernandez over 9 years ago in reply to Jay patel

TI__Mastermind 41790 points

Hi Jay,

It sounds like we are discussing the data transformer here. Please confirm. Since the data side of the data transformer is connected to the secondary load, you should still maintain proper isolation between the secondary and poe front end.

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Layout Guide for POE design