PoE Subsystem

Overview

The PoE subsystem lets the switch power devices, IP phones, wireless access points, cameras, over the same twisted-pair cable that carries their data, removing the need for local power at each endpoint. It acts as power-sourcing equipment under the IEEE 802.3at standard.

How it works

Before energizing a port, the PoE Controller IC ICs apply a low test voltage and look for the standardized resistive signature that marks a compliant powered device; only then do they classify its power class and switch on the rail. Each port's delivery is gated by a Power MOSFET under controller supervision, so faults or overloads disconnect individually without affecting neighbors. A Isolation Transformer provides the galvanic barrier between the switch's internal supply and the cable plant, and a sense-and-filter network of SMD Passive (R/C/L) lets the controllers meter current per port and enforce the shared 740 W budget. The whole subsystem rides on a dedicated Bare PCB daughtercard.