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Features and Benefits

  • Compliant with IEEE 802.3at Type 1 and 2
  • Supports LTPoE++® Up to 90W
  • Supports Dual-Signature PDs
  • Fully Autonomous Operation without Microcontroller
  • Very Low Power Dissipation
    • 0.1Ω Sense Resistance
    • Low RDS(ON) External MOSFET
  • Very High Reliability 4-Point PD Detection
    • 2-Point Forced Voltage and Forced Current
  • Robust Short-Circuit Protection
  • Cable Surge Protected ±80V OUT pin
  • Classification Dependent ICUT and ILIM Current Thresholds
  • Supports 2-Pair and 4-Pair Output Power
  • UltraPWR Mode Supports Custom PDs up to 123W
  • Pin-Selectable Detection Backoff Timer for Midspans
  • Pin Programmable Legacy PD Detection
  • Pin Programmable Maximum Power Mode
  • Status LED Pin
  • Available in 20-Pin QFN and 16-Pin SO Packages

Product Details

The LTC4279 is an autonomous single port power sourcing equipment (PSE) controller designed for use in IEEE 802.3at Type 1, Type 2 and LTPoE++ compliant Power over Ethernet (PoE) systems. The LTC4279 provides fully autonomous IEEE 802.3 and LTPoE++ compliant operation without a microcontroller. The LTC4279 simplifies PSE implementation, requiring only a single supply and a small number of passive support components.

The LTC4279 delivers lowest-in-industry heat dissipation by utilizing a low-RDS(ON) external MOSFET and a 0.1Ω sense resistor, eliminating the need for expensive heat sinks and increasing efficiency.

PD discovery uses a proprietary dual-mode 4-point detection mechanism ensuring excellent immunity from false PD detection. Midspan PSEs are supported with physical layer classification and a 2.5 second backoff timer.

Legacy and custom PDs are supported with pin-selectable LEGACY and UltraPWR modes. LEGACY mode detects and powers pre-IEEE specification PDs. UltraPWR mode aggressively turns on and powers custom PDs requiring high inrush and/or operational currents.


  • PoE PSE Endpoints (Switch/Router)
  • PoE Midspan Power Injectors
  • Power Forwarders
  • Femto Cells
  • Security Systems

Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (2)

Design Resources

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.