TPS2372: Please help to advise RMPS_DUTY

Hello,

Thank you for your question. We have a TI Reference Design that is similar to this configuration. In our schematic, we populate both RMPS resistors:

http://www.ti.com/lit/an/slva986/slva986.pdf

The advice I gave above is for combined power to get more than 90W of power. In order to give the best advice moving forward, I need to understand what is trying to be accomplilshed. Is the goal to use UPoE, go beyond BT PoE, use two lower power PD's, have two for redundancy? 

Please correct me if I am wrong, but this schematic appears to be the same project as this post:

https://e2e.ti.com/support/power-management/f/196/p/830547/3072801#3072801

Can you confirm?

Currently I am working with Richard Yang on this project. Thank you!

Regards,

Michael Pahl

Hi Michael,

It is for BT 90W application. And it is same project to Richard Yang's. 

I cannot find out the RMPS_DUTY in the document.Should I floating?

Another question, 

Following is TI's reference design.

Is ti diode needed, what function is it?

Hello,

Thank you for letting me know you are looking for a BT 90W solution. 

My understanding of your schematic is that you will need both RMPS_DUTY resistors. 1.3K resistor should be fine, but it is calculated with equation 3 in this PDF: http://www.ti.com/lit/ds/symlink/tps2372.pdf

For your second question, yes you will need the diodes. They provide protection from the circuitry. When one PD turns on, if the other does not have the diode it could damage the PSE. However, I will note this drives efficiency down. 

Can you please explain why you want two PD devices? One TPS2372 can be a class 8 PD, and the diodes would not be needed. 

Regards,

Michael Pahl

User4206464, It has been nearly a week without a reply from your side.  Do you consider this thread closed?

Thanks,