Features

• 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 (I_LIM)
• 7-Bit Programmable Overload Currents (I_CUT)
• Fast Shutdown
• 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 LTC4266 SW Compatible
• 1MHz I²C Compatible Serial Control Interface
• Midspan Backoff Timer
• Supports Proprietary Power Levels Above 25W
• Available in 38-Pin 5mm × 7mm QFN Package

Typical Application

Description

The LTC®4274 is a single power sourcing equipment 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 LTC4274 includes advanced power management features, including current and voltage readback and programmable I_CUT and I_LIM thresholds. Available C libraries simplify 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 LTC4274 is available in a 5mm × 7mm QFN package that significantly reduces board space compared with competing solutions.