National Semiconductor recently released what it claims is the industry's first 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.
Devices powered by a PoE network include IP phones, security cameras and 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 says the LM5071 is 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 part 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.
"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, a director at National'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 optimise 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."
Fabricated with National's ABCD150-XV1 high-voltage analog bipolar/CMOS/DMOS technology and the LM5071 offers advantages such as an integrated, high-frequency, current-mode DC-DC controller, user-programmable under-voltage threshold and hysteresis, and a highly accurate fault current control loop. It features a maximum input voltage of 80 V, user-programmable oscillator frequency up to 1 MHz and over-temperature protection, plus a voltage reference and high-performance error amplifier for non-isolated applications. It comes in a TSSOP-16 package.
For more information contact Simon Churches, Arrow Altech Distribution, +27 (0)11 923 9600, [email protected]
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