The LTC4266 is a four-port PoE controller for power sourcing equipment (PSE) required to provide IEEE 802.3at (25.5 W) or proprietary higher power levels. Providing up to 100 W over four-pair Ethernet cabling, the controller is compliant with the new IEEE 802.3at PoE+ standard and backward compatible with the prior IEEE 802.3af standard. To help conserve power, the controller delivers the industry’s lowest heat dissipation by using low RDS(on) MOSFETs and 0.25-Ω sense resistors, eliminating the need for heat sinks.

The POE controller is suitable for a wide variety of PSE applications, including next-generation switches, routers, hubs, and midspans. It uses a proprietary dual-mode four-point detection mechanism that ensures immunity from false PD detection. Power management functions include prioritized fast shutdown, 14.5-bit-per-port voltage and current readback, 8-bit programmable current limits, and 7–bit programmable overload current limits. A 1-MHz I2C interface allows a host controller to digitally configure the IC or query port readings. ($6.95 ea/1,000 — available now.)