TPS23754EVM-383: Schematic review request on PoE

Hi Joe,

Sure. We will take a look on your schematic and get back to you in one week.

Best regards,

Diang

Hi Diang

Thank you for schematic checking, but customer and I do not use PoE before, can I book a meeting with you to have a brief introduction of PoE and How can draw the schematic with this device?

I have some misunderstanding on the transformer that customer use. The right datasheet is attached here:H16120SCG POE yxz.pdf

Thank you!

Best regards

Joe

28 AUG

Hi Joe,

Sorry that I have time conflict at your proposed time. Please find the below links. Hope they can help.

https://confluence.itg.ti.com/display/POE/Power+over+Ethernet+%28PoE%29+-+Confluence+Home+Page

The training videos are very helpful for beginner. 

www.ti.com/.../power-over-ethernet-poe-training-series.html

If the customer still have questions they can send me the follow-up or we schedule a meeting later.

Best regards,

Diang

Hi Diang

I see in some of our reference design, the CM choke is in the data side, like 23730 and checklist, but I see another reference design which put the CM choke in the Power side: PMP21961A(001)_Sch.pdf

Is there any theory to decide which side the CM choke should be placed.

Thank you

Best regards

Joe

29 Aug 

Hi Joe,

CM chokes are commonly on the data side. This makes the CM chokes can have a smaller magnetic core area.

If they are on the PoE side, they need to be able to hold higher current meanwhile without flux density saturation. 

Best regards,

Diang

Hi Diang

 what’s the function of this circuit in EVM? In data sheet that mentions GAT2 may not be used, but what is the conditions that GAT2 is not needed?  

Hi Joe,

The GAT2 is normally used for active clamping forward (ACF) converter. This circuit to drive the P-MOS of the ACF converter. Looks like in your case it is an ACF converter.

If the customer applies flyback converter, normally they only need GATE and do not need GAT2.

Best regards,

Diang

Hi Diang

The attachment is the reversed schematic: xm.r3568.f-1-v0-POE.pdf

In Socket QN3, can this device applied? Way-on-WM15P10M2.pdf

In Socket QN5，QN7, can this device appied?MMBTA06.pdf

Thank you!

Best regards

Joe

4 Sep

TI US was closed Sep 4th, please expect some delays.

Hi Diang

1. Can customer replace the shield inductor used in reference design as marked in the picture below with common inductor? Apart form the Inductance DCR and saturation current is there any other requirement for the inductor?

2. 1.5mH is a not commonly used inductance in customer side, can it be changed to the other value?

thank you!

Best regards

Joe

8 Sep

Hi Diang

the attachment is the final Schematic and PCB layout, could you help to review?

Schematic:XM.R3568.F-1-V0.brd

Layout:0624.xm.r3568.f-1-v0-POE.pdf

Thank you

Best regards

Joe

12 Sep

Hi Joe,

The schematic looks good to me.

For the layout please follow the attached guidance.1016.PoE Layout Check LIst.xlsx

Let me know if you have any further questions or concerns. 

Best regards,

Diang

Hi Joe,

I will close this thread for now. Please reply or open a new thread if you have further questions.

Best regards,

Diang