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POE Network freeze

Other Parts Discussed in Thread: LM22676

Hi,

I am using the circuit attached to generate +5V using LM22676 to supply a Beagle Bone board. 

the board runs OK in the LAB with network connectivity (I use a POE injector), but Ethernet stop responding when running for 1 day or 2 in a building network

using POW switches.

I just want to make sure that the power supply circuit attached is OK, not sure about magnets connection.

Thanks.

  • The circuit diagram seems fine. The transformer is POE rated as well.

    When you say "stops responding after 1 or 2 days", do you know if the powered device (PD) still had power or did the PSE drop power causing the ethernet data to be dropped?

  • Hi,

    Thanks for the quick response.

    My customer says that PD still has power, but network is gone, they try ping but there is no response.

    Do I need to terminate the not-connected center tap pins of the transformer with 0.1uF?

    I'll double check if PD still has power this weekend.

    Thanks.
  • We usually rely on the recommendation from the PHY vendor for how to terminate the data only side center taps. Each vendor will provide that recommendation. Can you go to the PHY datasheet and see what they recommend? For the cable side, since there are EMI and ESD concerns, the "Bob Smith" terminations are usually used but these to my knowledge do not depend on which PHY is used.