PD controllers have built-in switchers

The LTC4269-1, LTC4269-2, and LTC4278 are IEEE 802.3at-compliant PoE+ interface controllers that have integrated switching regulators for 25.5-W PD applications. The controllers support two-event classification and are backward compatible with IEEE 802.3af devices. They integrate the PD controller and either a synchronous flyback controller (LTC4269-1 and LTC4278) or synchronous forward controller (LTC4269-2).

The PD controllers cater to video-conferencing stations, RFID readers, pan-tilt-zoom security cameras, and long-range wireless access points. A 100–V hot-swap MOSFET isolates the PoE interface controller and dc/dc converter during detection and classification, while providing 100–mA of inrush current for power-up transitions with any PSE. (Ea/1,000: LTC4269-1, $2.40; LTC4269-2 and LTC4278, $2.60 — available now.)

Linear Technology , Milpitas , CA
Information 408-432-1900
http://www.linear.com