New Industry Products

National Intros Single-Chip, PoE Controller

January 15, 2006 by Jeff Shepard

National Semiconductor Corp. has introduced a single-chip solution specifically designed for Power over Ethernet (PoE) devices that operate from alternative power sources or the PoE-enabled network. The LM5071 is a Powered Device (PD) interface and dc-dc converter IC that simplifies the design of a variety of PoE applications that require an auxiliary power source such as an AC adapter.

"Powering the device from an AC adapter can be tricky and requires forethought by the IC designer. The LM5071 solves the auxiliary power interface problem encountered by many PoE equipment designers with an elegant, integrated PD solution," said Paul Greenland, director of strategic marketing for National Semiconductor's Power Management group. "This new addition to National's PoE power product family accepts a wide range of AC adapter voltages, giving equipment designers the flexibility to optimize total system cost. The LM5071 builds on the success and learnings of its predecessor, the LM5070, to provide an auxiliary-powered PD solution that is superior to any on the market today."

Devices powered by a PoE network include IP phones, security cameras and wireless local area network (WLAN) nodes connected through Ethernet networking cables and ports. Operating these PoE devices from alternate power sources is often necessary to relieve the burden on the Power Sourcing Equipment (PSE) or to operate the device on a network that is not PoE-enabled. Current solutions limit the choice of auxiliary power sources, which can drive up overall system cost or complexity.

National's LM5071 is claimed to be the industry's first single-chip, IEEE 802.3af-compliant PD interface port and pulse-width modulator (PWM) controller specifically designed to accept power from external AC adapters. The LM5071 integrates a PD front end that accepts power from the PSE or auxiliary power to a single chip with a DC-DC controller that steps down the input voltage to power various PD loads.

National's LM5071 is available in lead-free and standard small-footprint TSSOP-16 packages. The product is priced at $1.45 each in 1,000-unit quantities.