I was searching, but was not able to find an answer which is helping me. This is the first time I'm confronted with implementing something like this, so please excuse if this is a dumb question...

My question is as follows: We have an existing PoE infrastructure, the task I'm facing is the wish to power some specialized devices from the PoE supply, but without utilizing Ethernet.

I was looking at the MAX5922 PSE controller, to extract the power. Would it work even if there is no Ethernet controller communicating to the PoE switch?

Can maybe someone hint me into the right direction?


  • \$\begingroup\$ The PoE and Ethernet protocols are completely independent of each other. You can have either one without the other. \$\endgroup\$
    – Dave Tweed
    Commented Apr 9, 2021 at 12:09
  • \$\begingroup\$ You mean the switch will not stop power supply just because there is no real Ethernet device connected? This is what I was hoping for \$\endgroup\$
    – MPArx
    Commented Apr 9, 2021 at 13:06

1 Answer 1


Cisco's PoE switches and routers will power remote devices that show a certain "power signature" called MPS.

Directly from Cisco's "Troubleshooting Power Over Ethernet" application note:

"The switch uses maintain power signature (MPS) to detect the continued presence of a powered device after detection and after power is applied. As long as a power signature is present, the switch provides PoE.

The powered device must maintain its power signature to maintain a PoE feed from the switch. PoE is typically removed within 500 milliseconds after the switch no longer detects a power signature. All disconnect methods occur at the physical layer."



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