The LTC4265 is a 3rd generation Powered Device (PD) Interface controller intended for IEEE 802.3at high power Power-over-Ethernet (PoE) applications up to 25.5W. By supporting 1-event and 2-event classification signaling as defined by IEEE 802.3, the LTC4265 can be used in a wide range of product configurations. A 100V MOSFET isolates the DC/DC converter during detection and classification, and provides 100mA inrush current for a smooth powerup transition. The LTC4265 also includes complementary power good outputs, an on-board signature resistor, undervoltage/overvoltage lockout and comprehensive thermal protection. All Linear Technology PD solutions include a shutdown pin with signature corrupt to provide flexible auxiliary power options.