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RE: TPS23861: POE switch port is not power

user5084306
Prodigy 50 points
Other Parts Discussed in Thread: TPS23861, TPS23861EVM-612

Dear all,

I have build 10 board using TPS23861 Auto mode,but I found only 2 board can work as expected, that is they can supply the port when PD is inserted, and output 19V pulse when the port has no PD inserted. But the remains 8 board can not work, I measure the voltage at port, the VPWR-VDRN is always 0, VPWR-GND is 48.3V.

I have changed the TPS23861, but I still can not fix this problem.

Can you help me?

  • 0
    TI__Genius 15685 points
    Hi User5084306,

    Can you send me your schematic and I can take a look? In addition, can you measure the RESET pin status of the TPS23861 and make sure it is high? Is there any I2C connection that you can read register status? Thanks.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Prodigy 50 points

    Dear Penny,

    I use the four port  auto mode reference design according to the datasheet. I attached the RESET pin to VDD, and I measured the voltage is 3.32V. Sorry,I2C is not used in my design.

  • 0 in reply to user5084306
    Prodigy 50 points
    About the schematic I sent it to you by email, because I do not know how to past it in this vonversation. If you can not receive it, Please give me your suggestion so that I can resend it to you.
  • 0 in reply to Penny Xu
    Prodigy 50 points

    Hi Penny,

    I have a new progress with the problem: Since some of the board is good, that means it can supply PD as expected. The DRAIN voltage of normal working board can out put puls when the port is open. But the problem board the DRAINx is always 0V or 48V, no pulse output. I exchange the TPS23861,found the problem is go with the chip.

    It seems the default status of the TPS23861 is not same. Is this case is normal? 

    In my design,I connected the RESET and VDD together.and VDD is enabled by 48V power.

  • 0 in reply to user5084306
    TI__Genius 15685 points

    Hi user5084306,

    Glad to see you had great progress!

    That's not normal. The default status of TPS23861 should be the same with autonomous mode enabled. I doubt your TPS23861 has been damaged during board manufacturing. The best way to check is to solder the "bad" IC to TPS23861EVM-612 if you have one, and use PI commander GUI to check the status of TPS23861. Thanks.

    Best regards,

    Penny