The Cisco PWR-3900-POE Power Supply is an internal AC power module for Cisco ISR 3925 and 3945 routers that provides router power and integrated Power over Ethernet to connected devices. It accepts 100–240V AC at 50–60 Hz and delivers PoE through a single unit, enabling IP phones and other network equipment to power from the router chassis in enterprise branch networks. Manufactured by Cisco Systems, this MPN PWR-3900-POE is used as a replacement or upgrade for Cisco ISR 3900 Series routers, with common replacements including PWR-3900-AC, PWR-3900-DC, and PWR-3845-AC-IP.
