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Original question:

TPS23730EVM-093: When we plug-In 802.3at 30W PoE Injector into a 802.3bt 60W Sink with PD Class selected for 60W Requirement...

TPS23730: Changing power requirement at run time

Abhishek singh
Expert 2000 points
Part Number: TPS23730

Hi  Team 

We are making one product where we need to power system through three power source 

1) PoE (60W)

2) DC power Supply (60W)

3) USB type C PD (60W)

Only some of our application requires 60W power supply. If customer  plug in power  source  which is  not  capable of providing 

60 W power. Then  we  should  able to detect the same and send notification to user  that certain application will not run and  limit 

the functionality.

1) Please  suggest a  way to achieve above  functionality with each power supply .

2) Can TPS23730 report its negotiated power to MCU / Processor .

    

 

  • 0
    TI__Mastermind 21320 points

    Hello,

    The TPS23730 can report its negotiated power when powered by a PSE:

    The pins are TPH and TPL. Please see Table 2. in the data sheet: 

    TPH / TPL::

    <= 13W (Type 1, but could be 2-4):  High / High

    = 25W (Type 2, but could be Type 3 or 4): High / Low

    > 25W (Type 3/4): Low / High

    These signals can be in parallel or series. 

    Additionally, if the PSE is .bt, the TPS23730 has a BT pin that will indicate it detected the first long finger.

    However, if the TPS23730 is powered by a DC power source or some other auxiliary power supply, it does not have a way to decipher its allocated power. These power types do not send a power negotiation signal like PoE, so there is no way for the PD to know how much power it is receiving. That is one of the major reasons for PoE, over a simple power switch over Ethernet. 

    It is possible to build power limiting circuits with the TPS23730, but the control signals would need to come from an MCU if it is not PoE. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments