Hello,
I would like to use the TPS2372 as the PD and TPS23753A as the DCDC Regulator as we already have a tested design for that DCDC Regulator.
I need the extra power for a PSE that will be included in the design.
Is it possible to do this, if that is the case how should i configure the TPS23753A? In other words, is it possible to Disable to PD part of the regulator and only run it as a Regulator
Thanks for the Help!
BR Martin
Hello Brandon,
Thanks for the reply!
By "Poe in" I meant midspan.
In a sense they will be in parallel I suppose, all 3 will be connected to the + side of the rectifier and then the negative connection is unclear due to the "PD function" of the DCDC Regulator.
The goal is to use the external PD to negotiate, the Regulator to supply the unit, and have the ability to connect a second unit to this one with the PSE. 
Br Martin
Hi Martin,
This is possible however your connections need to be altered slightly.
In order to achieve the TPS2372 to negotiate power, then TPS23753A for DCDC and another PSE, you will need to connect TPS2372 to supply from rectifier bridge then connect the PSE and TPS23753A in parallel to the output of TPS2372. This will allow it to go through handshake process without interference from other. To do this connect TPS2372 normally to VDD,VSS, then use VDD,RTN for in the input to both PSE and TPS23753A. I will attached a simplified schematic as to what this looks like.
Make sure TPS2372 is configured to support power for both the PSE and DCDC regulator. For the TPS23753A, it is possible to use as just DCDC regulator, once voltage is applied above the threshold, the passFET will close.
Very Respectfully,
Brandon Beader
The RTN of TPS23753A should be a separate ground. I will attach a more clear high level schematic for reference.
You do not need a Rcls resistor for the TPS23753A since it does not matter because the TPS2372 will be doing your port power allocation. Once the TPS23753A receives voltage above a certain threshold the internal FET will close. Handshake for the TPS23753A is being bypassed, therefore you will need to configure the Rcls resistor for the TPS2372 to allocate enough power for both the TPS23753A as well as the PSE.
Very Respectfully,
Brandon Beader
Just noticed a thing in your picture, isn't the TPS23753A acting as the DCDC converter?
No the TPS23753 is not an integrated solution for DCDC converter. The TPS23753A is just the controller for the DCDC converter. Attached is reference design for TPS23753A (PMP11271) which uses the TPS23753A as the controller to drive the DCDC converter.
