Product category:
Power Supply ICs and Controllers
News Release from: National Semiconductor | Subject: LM5070
Edited by the Electronicstalk Editorial
Team on 08 October 2004
Ethernet power comes down to single-chip
solution
The LM5070 is a single-chip power device claimed to dramatically simplify the design of a wide variety of systems using power over Ethernet.
The LM5070 is billed as the first single-chip solution to feature the high performance and tiny package footprint needed to dramatically simplify the design of a wide variety of systems using power over Ethernet (PoE) As the name implies, PoE networks power devices such as IP phones, security cameras, wireless local area network (WLAN) nodes and even musical instruments through Ethernet networking cables and ports
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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Whereas competing solutions use two or three chips, National's LM5070 is the industry's first single-chip power device interface port and pulsewidth modulator (PWM) controller that meets the IEEE802.3af standard.
The LM5070 integrates an 80V, 400mA line connection switch and associated PoE interface circuits with a DC/DC controller that steps down the 48V input to power various loads.
"The LM5070 marks National's breakthrough entry into one of the most exciting, fast-growing global markets available", said Edward Lam, Vice President of National Semiconductor's Power Management Group.
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"This single-chip product combines National's strengths in analogue, power management, Ethernet networks, ultrasmall packaging and process technologies to create an elegant solution that is clearly superior to anything on the market today".
The LM5070 is built at National's state-of-the-art fabrication facilities in Greenock, Scotland, and Arlington, Texas, using the company's ABCD150-XV1 high-voltage analogue bipolar/CMOS/DMOS process technology.
This highly integrated product offers advantages such as an integrated high frequency current-mode DC/DC controller, user-programmable undervoltage threshold and hysteresis, and a highly accurate fault current control loop.
It features a maximum operating voltage of 75V, user-programmable oscillator frequency up to 1MHz, ove-temperature protection, plus a voltage reference and high-performance error amplifier for nonisolated applications.
National's LM5070 has a number of unique characteristics that make it easy to design-in.
The user can program the undervoltage lockout (UVLO) trip-point and hysteresis completely independently.
This allows the user to control startup line currents and program the start and stop voltage points as desired for a variety of system applications.
Inrush current programming allows the user full control over inrush transient which is programmed to the current desired via an external resistor on the RCLP pin.
Alternatively, if the default inrush limit (375mA) is desired, no external components are required - the designer simply leaves the RCLP pin open.
Thanks to internal power sequencing the system designer does not have to control the DC/DC convertor system with "power good" signals or any other external communications interface.
Communication between the POE PD interface section and the DC/DC convertor is completely integrated within the LM5070.
The device also integrates the precision voltage reference and error amplifier for DC/DC feedback in nonisolated convertors.
This provides pull-up for optocoupler transistors in isolated designs.
The 25kohm signature resistor is disconnected after power device detection to avoid power and efficiency losses.
And the oscillator for the switching regulator controller is fully user programmable, easing power supply control loop design and allowing the user to maximise regulator performance.
Power over Ethernet solutions are rapidly growing in popularity.
Because PoE devices don't require wall-mounted power supplies, overall systems costs are lower.
For IP telephony, uninterruptible power supplies guarantee higher reliability and less susceptibility to power surges, theft, interruption or disconnection.
In addition, the worldwide usage of the RJ45 power connector ensures global compatibility of PoE devices.
For wireless access point applications, these systems don't require AC power sources, power lines, or outlets.
Finally, PoE-enabled devices offer superior management flexibility with remote power up/down capability.
According to research firm Venture Development Corp, the global market for PoE-enabling silicon ICs is expected to grow from an estimated 133 million units in 2004 to 496 million units in 2007, a 55% compound annual growth rate.
National's LM5070 is available in small-footprint LLP-16 or TSSOP-16 packages.
Lead-free package options are also available.
The product is priced at $1.75 each in 1000-unit quantities.
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