Quad IEEE 802.3at Power Over Ethernet Controller

The LTC4266 is a quad PSE controller designed for use in IEEE 802.3 Type 1 and Type 2 (high power) compliant Power over Ethernet systems. External power MOSFETs enhance system reliability and minimize channel resistance, cutting power dissipation and eliminating the need for heatsinks even at Type 2 power levels. External power components also allow use at very high power levels while remaining otherwise compatible with the IEEE standard. 80V-rated port pins provide robust protection against external faults.

The LTC4266 includes advanced power management features, including current and voltage readback and programmable ICUT and ILIM thresholds. Available C libraries simplify power-management software development; an optional AUTO pin mode provides fully IEEE-compliant standalone operation with no software required. Proprietary 4-point PD detection circuitry minimizes false PD detection while supporting legacy phone operation. Midspan operation is supported with built-in 2-event classification and backoff timing. Host communication is via a 1MHz I2C serial interface.

The LTC4266 is available in a 5mm × 7mm QFN package that significantly reduces board space compared with competing solutions. A legacy-compatible 36-pin SSOP package is also available.

Applications

* High Power PSE Switches/Routers

* High Power PSE Midspans

* Four Independent PSE Channels

* Compliant with IEEE 802.3at Type 1 and 2

* 0.34Ω Total Channel Resistance

* 130mW/Port at 600mA

* Advanced Power Management

* 8-Bit Programmable Current Limit (ILIM)

* 7-Bit Programmable Overload Currents (ICUT)

* Fast Shutdown of Preselected Ports

* 14.5-Bit Port Current/Voltage Monitoring

* 2-Event Classification

* Very High Reliability 4-Point PD Detection

* 2-Point Forced Voltage

* 2-Point Forced Current

* High Capacitance Legacy Device Detection

* LTC4259A-1 and LTC4258 Pin and SW Compatible

* 1MHz I2C Compatible Serial Control Interface

* Midspan Backoff Timer

* Supports Proprietary Power Levels Above 25W

* Available in 38-Pin 5mm × 7mm QFN and 36-Pin SSOP Packages