LTC4264/LTC4265 High-Power PD Interface Controllers

Analog Devices' LTC4264 and LTC4265 are powered device (PD) interface controllers intended for IEEE 802.3at high-power Power over Ethernet (PoE) applications up to 35 W and 25.5 W, respectively.

By including a precision dual current limit, the LTC4264 keeps inrush below the IEEE802.3af current limit levels to ensure interoperability success while allowing for high power PD operation. The LTC4264 includes a field-proven power MOSFET delivering up to 750 mA to the PD load while maintaining compliance with the IEEE802.3af standard. Complementary power good outputs allow the LTC4264 to interface directly with a host of DC/DC converter products. The LTC4264 provides a complete signature and power interface solution for PD designs by incorporating the 25k signature resistor, classification circuitry, input current limit, undervoltage lockout, thermal overload protection, signature disable, and power good signaling.

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 100 V MOSFET isolates the DC/DC converter during detection and classification and provides 100 mA inrush current for a smooth power-up transition. The LTC4265 also includes complementary power good outputs, an onboard signature resistor, undervoltage/overvoltage lockout, and comprehensive thermal protection. All PD solutions from ADI include a shutdown pin with signature corrupt to provide flexible auxiliary power options.

The LTC4264 and LTC4265 PD interface controllers can be used along with a variety of DC/DC converter products to provide a complete, cost-effective power solution for high-power PD applications. The controllers are available in a low profile (4 mm × 3 mm) DFN package. The LTC4264 and LTC4265 are ideal for RFID reader systems, PTZ security, and 802.11n access points.