LTC4274 - Single PoE+ PSE Controller

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 ICUT and ILIM 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.

  • 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
  • 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
  • PSE Switches/Routers
  • PSE Midspans
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LTC4274CUHF#PBF5x7 QFN-38C$6.43$4.50
LTC4274CUHF#TRPBF5x7 QFN-38C$4.56
LTC4274IUHF#PBF5x7 QFN-38I$7.07$4.95
LTC4274IUHF#TRPBF5x7 QFN-38I$5.01
Demo Boards
Part NumberDescriptionPrice
DC1567BLTC4274 Demo Board | IEEE802.3at Power Over Ethernet PSE$75.00
Reliability Data
Product Selector Card
Press Release
CAD Symbol CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprint compatible with Cadence ORCAD® v16.5 or later, Mentor Graphics PADS® v9.5 or later, and Altium 14.2.5 or later.
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LTC4274 Footprints and Symbols