Linear Tech Quad PSE Controller Addresses IEEE 802.3at PoE+ Standard

Linear Technology Corp. introduced the LTC4266, a 4-port Power over Ethernet (PoE) controller for Power Sourcing Equipment (PSE) required to provide IEEE 802.3at (25.5W) or proprietary higher power levels. Next-generation PoE applications call for more power to support demanding features, while increasing power efficiency in an effort to be more "green" and reduce costs.

The LTC4266 provides up to 100W over 4-pair Ethernet cabling and is fully compliant with the new IEEE 802.3at PoE+ standard and backward compatible with the prior IEEE 802.3af PoE standard. To help conserve power, the LTC4266 is said to deliver the lowest-in-industry heat dissipation by using low R_DS(ON) MOSFETs and 0.25Ω sense resistors, eliminating the need for expensive heat sinks and providing a more robust PSE solution.

The LTC4266 is suitable for a wide variety of PSE applications, including next-generation switches, routers, hubs and midspans. Users will appreciate the extremely low power dissipation which makes thermal design significantly easier than when designing with PSEs that integrate more fragile, normally higher R_DS(ON), MOSFETs. Up to four independent PSE channels are available.

IEEE 802.3at powered devices (PDs) can request up to 25.5W of power by responding to 2-event classification from the LTC4266, confirming that the PD is indeed a high power device. PD discovery is accomplished using a proprietary dual-mode, four point detection mechanism that ensures the best immunity from false PD detection. Advanced power management also includes 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 1MHz I²C interface allows a host controller to digitally configure the IC or query port readings.

The LTC4266 is offered in commercial and industrial temperature grades, and is available in RoHS-compliant 5 x 7mm QFN-38 or SSOP-36 packages. The LTC4266 is priced starting at $6.95 each in 1,000 piece quantities and is available in production quantities. The LTC4266 provides an upgrade path from Linear’s existing PSE controllers, including the IEEE 802.3af pin-compatible LTC4258 or LTC4259A.