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TPS2379 application

Chen Bogey8
Mastermind 9990 points
Other Parts Discussed in Thread: TPS2379, LM5020

Dear Sir

good days,

We have use TPS2379 +LM5020 in POE application.

and LM5020 output is 12V/4A.

We have smoe issue as below and may you pls have some suggestion to us?

When we add load first then plug in PSE, the PSE can't power on TPS2379 +LM5020.

But if we plug PSE first then add load, then output is normal.

                                     Best regards,

                                             Bogey

 

 

 

 

  • 0
    TI__Mastermind 42795 points

    Did you connect the TPS2379 CDB pin to the LM5020 SS pin? CDB will disable the converter using the SS pin until the TPS2379 hot swap is fully enhanced (See figure 25 in the TPS2379 DS).

    Additionally, you should use the TPS2379 T2P pin for load control. The PD load current must be managed by the PD according to the IEEE POE standard.

  • 0
    TI__Expert 7990 points

    Look at the input V/I profile of the PD and verify that it is compatible with your PSE.

    If the PSE should run the load (considering the loop resistance also)  see if you can start isolating your design issue by applying power directly to the converter (LM5020) input, and then at the input to the TPS2379 with the converter connected.