Product category: Power Supply ICs and Controllers
News Release from: National Semiconductor | Subject: LM5072
Edited by the Electronicstalk Editorial Team on 21 March 2006
Controller provides more power over
Ethernet
A new single-chip PoE controller allows designers to operate PoE appliances at higher power levels than standard IEEE802.3af devices.
National Semiconductor has released the industry's first single-chip PoE controller for higher-power PoE applications The LM5072, which integrates a programmable power interface port and a pulsewidth modulation (PWM) controller, allows designers to operate PoE appliances at higher power levels than standard IEEE802.3af devices
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
Related stories
Dual-port Gigabit Ethernet transceiver
National Semiconductor has announced the DP83862, a low-cost, highly integrated dual-port 10/100/1000 physical layer transceiver.
World's smallest multifunction supervisory ICs
National Semiconductor has announced a family of supervisory ICs with a variety of factory-programmable features that can be configured in hundreds of possible combinations.
National designed the LM5072 with programmable current limiting that allows it to draw up to 25W from a PoE-enabled port, as many emerging PoE applications require power that exceeds the limit of the existing standard.
For standard 802.3af Powered Devices (PDs), the current may be programmed to any value between 150 and 800mA, or the programming resistor can be simply disconnected to switch the LM5072 to the default mode with 440mA maximum current draw.
The LM5072, which has maximum input voltage and current ratings of 100V and 800mA, also supports applications that accept power from auxiliary sources.
Further reading
Leadless leadframe package shrinks LDO
National Semiconductor has introduced a full-featured 500mA LDO regulator for medium-current applications in computing devices and portable products.
Boomer shrinks stereo headphone amplification
New from National Semiconductor, the LM4811 Boomer audio amplifier is a 105mW stereo headphone amplifier for use in 3 and 5V systems requiring a headphone output and volume control.
Frugal dual-channel A/D conversion
National Semiconductor has introduced a dual-channel 8bit A/D convertor with record low-power dissipation levels.
National will be demonstrating the LM5072 at PCIM Europe (30th May to 1st June 2006, Nuremberg, Germany) in Hall 12, Booth 124.
The LM5072 joins National's LM5070, which integrates a 375 mA PoE interface circuit with a DC/DC controller; and the LM5071, a single-chip solution specifically designed for PoE devices that operate from alternative power sources.
Applications for the LM5072 include VoIP phones, remote security cameras, card readers, wireless access points, computer telephony, PDs in PoE systems and 48V telecomms power supply controls.
"National's LM5072 responds to the increasing market demand for complete solutions for higher-power PoE applications, as well as for devices that can be powered from auxiliary power sources", said Paul Greenland, Director of Strategic Marketing for National Semiconductor's Power Management Group.
"With the addition of the LM5072 to our family of PoE products, National can provide designers with an integrated, single-chip PD solution to their PoE design challenges, whether those applications are for 802.3af networks or for customised, higher-power PoE systems".
The LM5072's PoE port input and internal PD interface MOSFET are specified to an absolute maximum voltage of 100V.
Designers can set the port current limit to the default 802.3af level or program it from 100 to 800mA.
The inrush current limit defaults to 150mA, but can be programmed over the same range as the port current limit.
The precision 25kohm signature detection resistor is also integrated within the LM5072.
The LM5072's fully configurable AC adapter interface allows designers to connect auxiliary power to either the front-end PoE port or rear DC/DC convertor.
With a rear auxiliary supply, the LM5072 can disable the PoE interface to reduce power drawn from the Power Sourcing Equipment (PSE) when auxiliary power is applied.
The LM5072's PWM controller includes a high-voltage bias regulator, programmable soft-start and programmable switching frequency with clock synchronisation capability.
The LM5072 is available with either 50 or 80% maximum PWM duty cycle, which allows the controller to support a variety of DC/DC convertor topologies and operation over an extended auxiliary supply-voltage range.
The LM5072 includes a 2%-accurate voltage reference and error amplifier for direct control of the output in nonisolated DC/DC applications.
The LM5072 is offered in the thermally enhanced 16-pin TSSOP-EP package, priced at $1.85 in 1000-unit quantities.
• National Semiconductor: contact details and other news
• Email this article to a colleague
• Register for the free Electronicstalk email newsletter
• Electronicstalk Home Page
Search the Pro-Talk network of sites
