The single-port Power over Ethernet (PoE) controller from Linear Technology is designed for  power sourcing equipment (PSE), delivering up to 123W of power over CAT-5e cable.

The IC delivers power to powered devices including legacy (up to 13W), IEEE 802.3at Type 1 (13W) and Type 2 (25.5W) power devices, the company’s proprietary LTPoE (up to 90W), and custom (up to 123W) devices. Output topologies supported are two- and four-pair, as well as single-signature and dual-signature architectures.  Resistor-adjustable power selection allows the LTC4279 to be configured for multiple sockets. According to the company, this simplifies design and the bill of materials. 

There is autonomous operation for PSE applications, including endpoints and midspan power injectors. A low-power sense resistor and external MOSFET simplify thermal design, compared with traditional PSEs which use less robust MOSFETs with higher R_DS(ON).  Discovery is accomplished using a four-point detection mechanism that ensures best-in-class immunity from false power device detection, says the company. 

The LTC4279 is offered in the industrial temperature grade (–40 to 85°C) and is available in RoHS-compliant 4.0 x 5.0mm QFN-20 and SO-16 packages.