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TPS23881B: TPS23881 Power

kerim akgün
Prodigy 30 points
Part Number: TPS23881B


Tool/software:

Hi,

I am designing a circuit using the TPS23881B with the following configuration:

  • 3 ports with 2 pairs (2x2)
  • 2 ports with 4 pairs (4x4)

The power supply can provide a maximum of 200W.

Here is the scenario I am considering:

If I connect 2 (90W) PD devieces to 4 pairs ports, 3 (15.4W) PD to 2 pairs ports. Total power for PD devieces will 226.2 W.

Here is I want to know what will be happend in this senario? 

Best regards,

Kerim 

  • 0
    TI__Mastermind 37111 points

    Hi Kerim,

    Thanks for reaching out!

    The PSE chip itself can not prevent your power exceeding the 200W power budget in your example.

    You may need a host IC to manage your power. In some common cases, you can set power priorities for different ports. If the power is about exceeding the 200W budget, the lowest priority port starts to be cut off. For host IC and PSE management, you can consider TI's FirmPSE solution, where MSP430 could be used as host IC. You can get the FirmPSE solution firmware by requesting in https://www.ti.com/product/TPS23881 as below:

    Best regards,

    Diang

  • 0 in reply to Diang Xing
    Prodigy 30 points

    Dear Diang,

    Thank you for your response.

    I am planning to use the TPS23881B chip in autonomous mode for my board, which will have 4 ports. As I understand, when using the chip in autonomous mode, all ports will be set to the same power output. I intend to configure the ports to provide up to 90W of power.

    The power supply for my board can deliver up to 200W. So, if I connect two PD devices that require 90W each, the maximum power drawn would be 180W, which seems to be within the safe operating range.

    However, I have a question. What would happen if I connect a third PD device that also requires 90W? Would this cause any issues with the power distribution or performance of the board?

    I appreciate your guidance on this matter.

    Best regards,

    Kerim

  • 0 in reply to kerim akgün
    TI__Mastermind 37111 points

    Hi Kerim,

    Thanks for reply!

    I will look into your question and get back to you in this week.

    Best regards,

    Diang 

  • 0 in reply to Diang Xing
    TI__Mastermind 37111 points

    Hi Kerim,

    If in autonomous mode you may have a overload issue when 3rd 90W load is connected. Assuming your converter will limit the power to 200W, then your PSE input voltage may drop due to overload until reaches TPS23881B1's VPWR UVLO. Then the PSE may try again to source the 3x90W load. You may goes into a hiccup mode. 

    Using a control IC, like TI's MSP430 or MSPM0, could help to set priority (not at autonomous mode).

    Best regards,

    Diang