Power Over Ethernet Interoperability Guide

Dropout versus MPS

Let us summarize this for clarity: If for every 300 ms that the port current dips below 5 mA, the PD draws at least 10 mA for more than 60 ms (say the PD’s internal burst-timer is 60 to 65 ms), the PSE will declare that the signature was maintained and will not disconnect the PD. But if not, the dropout time will be deemed as having exceeded its limits, and the PD will be disconnected within 400 ms (the max of the dropout-time interval). The upper boundary of T_MPDO is a physical human limit for disconnecting one PD and “immediately” connecting another device.

NOTE “Power removal” or disconnect just refers to the PSE pass-FET ...