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TPS23730EVM-093: When we plug-In 802.3at 30W PoE Injector into a 802.3bt 60W Sink with PD Class selected for 60W Requirement. Will it going to operate the device till 30W consumption or there will be No power up on sink side.

satish sharma1
Prodigy 10 points
Part Number: TPS23730EVM-093
Other Parts Discussed in Thread: TPS23730, TPS23734

Hi Team TI, 

I am designing a sink side 60W 802.3bt Compatible power section. My question is, If I will pug-in a 30W 802.3at 30W support PoE in the system, Will it going to power up the system and upto 30W consumption it will keep it up or There will no power up at sink side. 

I need this clarification, to know, If 802.3at PoE injectors are compatible with 802.3bt , If for some use cases power consumption will not be exceeding 30W on 802.3bt system. 

Kindly do revert on this. 

Thanks and regards 

Satish Sharma  

  • 0
    TI__Mastermind 21320 points

    Hello,

    If the PD presents a valid detection and classification, the PSE should apply power. 

    Below is a picture of the TPS23730EVM-093 when connected to a Type 2 (IEEE802.3.at 30W) PSE: 

    You can see the detection, class and power up on VDD_VSS (blue). 

    Yellow, pink and green are TPH, TPL, and BT signals respectively. You can use these signals to determine how much power the PD can draw. If the PD tries to draw more power than the PSE can supply, the PSE will fold back. So the load needs to be managed. 

    Additionally, we do have the TPS23734 which supports 25W with all the same features as TPS23730 if that is a better solution for you.

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

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments