Power over Ethernet controller for power sourcing equipment

Linear Technology Corporation has introduced the LTC4279 single port Power over Ethernet (PoE) controller for power sourcing equipment (PSE), delivering up to 123W of power over CAT-5e cable for power-hungry applications. Demand for higher power delivery comes from a widespread set of applications, including LTE picocell base stations, LED signage, security monitoring systems, home automation and machine vision systems. The highly versatile LTC4279 delivers power to a wide variety of powered devices (PDs). This includes all legacy (<13W), IEEE 802.3at Type 1 (13W) and Type 2 (25.5W) PDs, Linear’s proprietary LTPoE++ (up to 90W), and custom (<123W) PDs. Two-pair and four-pair output topologies are supported, as well as single-signature and dual-signature architectures. Resistor-adjustable power selection allows the LTC4279 to be easily configured for multiple sockets, simplifying design and bill of materials.

The LTC4279 provides fully autonomous operation for a wide variety of PSE applications, including endpoints and midspan power injectors. A low power sense resistor and external MOSFET simplify thermal design; traditional PSEs utilise less robust MOSFETs with higher R_DS(ON).  PD discovery is accomplished using a high reliability four-point detection mechanism that ensures best-in-class immunity from false PD detection. The LTC4279 provides a comprehensive set of PD classification mechanisms to enable wide system compatibility. Robustness is reinforced with classification-dependent current cut-off and limit thresholds, short-circuit protection and ±80V cable surge protection.

The LTC4279 is offered in the industrial temperature grade (–40°C to 85°C) and is available in RoHS-compliant 4mm x 5mm QFN-20 and SO-16 packages. The LTC4279 is priced starting at $3.45 each in 1,000-piece quantities and is now available in production quantities. The LTC4279, combined with the LT4275 and LT4276 PD controllers, enable up to 123W end-to-end design.