Single Port PoE/PoE+/LTPoE++ PSE Controller

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.

Applications

* PoE PSE Endpoints (Switch/Router)

* PoE Midspan Power Injectors

* Power Forwarders

* Femto Cells

* Security Systems

* 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