LG-4T2XS-120P: a 2.5G PoE++ switch with four 90 W ports

ACWiFi opened the LG-4T2XS-120P to explain why a four-port 2.5G PoE switch uses such a large power adapter. The useful connection is between the PoE budget, the PSE chip, and the actual needs of an access point.¹

Ports and power

The unit has four 2.5G ports and two 10G SFP+ slots, with 802.3bt support up to 90 W per port. Its adapter is 48V/2.5A, or 120 W. ACWiFi measured 1.75 W with no network cable and 3.7 W with two 2.5G links.

Inside the chassis

The PCB uses substantial surge-protection circuitry around the RJ45 area. The RTL8372N switch integrates two 10G MACs and four 2.5G PHYs; W25Q16JVSIQ flash provides 2 MB. The RTL8239C PSE supplies 802.3bt to four ports. A TMI3286B handles the synchronous DC-DC stage.

Does an access point really need 90 W?

The source notes that some APs only operate at their intended capability with 90 W, using TP-LINK TL-7AP13000TCS-PoE/DC as an example. With less power, an AP may reduce transmit power, spatial streams, or functions such as USB/PoE out on related models. That does not mean every AP needs 90 W, so I check the AP datasheet before buying the switch.

ACWiFi recorded a price around 310 yuan at the time. The combination of four 2.5G ports, two 10G SFP+ slots, and PoE++ is compelling for a multi-AP Wi-Fi 7 installation, but I still budget for the 120 W total, heat, cabling, and transceivers.

Limits

The teardown identifies the components and management interface of this unit; it is not a continuous four-port 90 W stress test. I do not infer thermal performance, noise, or compatibility with every AP beyond the source's observations.

Sources