Power Electronics

Data Points

Autocompensating POL Converter

A 15-A nonisolated point-of-load (POL) converter from Artesyn Technologies, the SIL15E-12M incorporates an industry-standard I2C bus interface that simplifies setup and control. I2C programmable features include precision setting of both the output voltage and voltage margining facilities. Also, an active dc output control function significantly increases output voltage accuracy during normal operation and when voltage margining during system test. This autocompensation feature maintains the output set point typically within ±0.75% of nominal over time and under different temperature and load conditions.

Each converter is pre-programmed to standard default values stored in nonvolatile memory and only requires additional programming by customers who wish to change an operational function. The converters also feature an input voltage range of 10 V to 14 V, a 0.8-V to 3.36-V output range, and a full-load efficiency of 92%.

Programming the POL converters on a board under development is simply a case of connecting its I2C bus connector via a USB cable to a standard PC running a Windows-based graphical user interface. SIL15E-12M converters can be controlled independently or up to eight can be addressed simultaneously. The configuration software employs an intuitive, simple-to-use interface to minimize system prototype development time.

To request an evaluation kit or for more information, visit www.artesyn.com/powergroup/new_12vin_eclass_launch.htm.

42-V Automotive Electrical Systems

A few years ago, many members of the automotive industry were enthusiastically pursuing development of 42-V electrical systems in response to the rising demand for electrical power in cars. Although power demands continue to rise, expectations for the deployment of 42-V electrical systems have been lowered. Many of the companies that had initiated 42-V development programs have abandoned them. And although some vehicles are being released with 42-V power buses, the introduction of 42-V systems is occurring slower than expected.

In a paper presented at Convergence 2004, Thomas A. Keim examined some of the technical and economic reasons for the change in status and attitudes regarding 42-V electrical systems. As director of the MIT/Industry Consortium on Advanced Automotive Electrical/Electronic Components and Systems, Keim has played an active role in efforts to develop 42 V as a standard for automotive generation and distribution.

As Keim notes in “42 Volts — The View from Today,” the industry has done extensive work to identify, evaluate and correct the barriers to implementation of 42-V electrical systems. Many of the technical challenges cited relate to electrical arcing in 42-V components such as wiring, fuses, switches and relays, and connectors.

As researchers have learned, “arc behavior is demonstrably different at 42 V than at 14 V.” While arcing at the higher voltage presents new technical challenges, “they do not pose an insurmountable obstacle to using 42 V in automobiles.” Keim concludes, “Despite considerable searching, the industry has not found a showstopper problem, which would derail the use of 42 V.”

Instead, the factors holding back deployment of 42-V systems (or dual 14-/42-V systems) are economic challenges, such as how to finance the transition costs of adopting 42-V technology and how “to identify the value which justifies the expense” of the new technology.

“The early vision of 42 V as a cost reduction has proven unrealistic,” Keim writes. “But there is still the vision of 42 V as a cost-effective way to get more electric functions on the vehicle than is possible today. To be selected on this basis, 42 V must be the only way, or the least expensive way, to get the required level of power and function, and the cost must still be low enough so that the vehicle designer does not reconsider the specifications for power and function.”

To order a copy of Keim's paper, visit www.sae.org and enter “2004-21-0094” in the search field in the upper left-hand corner. Note that the paper is incorrectly titled on the Web site.Or, for more information, contact the author at [email protected].

PoE Midspan Patent

PowerDsine has been awarded a “spare pair powering” patent in China that further extends the company's patent portfolio in Power-over-Ethernet (PoE) technology. The patent #ZL 99815577.2, issued under certificate 161478 in China, pertains to PowerDsine's PoE standalone midspan products, which connect an Ethernet switch to PoE-enable an enterprise network.

In October 2002, the U.S. Patent and Trademark Office awarded patent #6,473,608 that pertains to PowerDsine's structured cabling system invention. The U.S. patent, much like the Chinese patent, addresses the process that detects all “power-enabled” elements in the Ethernet LAN so that power can be distributed safely via data Ethernet cabling infrastructure to those elements without affecting legacy devices.

Filter Subdues Ground Transients

The ground transient terminator (GTT) developed by ECM Electronics and 9 Corp. delivers a new form of protection against electrical transients and surges in electronic equipment. Using passive filter technology the GTT stops ground transients, eliminating common causes of lock-ups, crashes and system degradation.

The GTT slows the damaging rise and fall time of a transient voltage waveform rather than clipping it off, controlling frequency rather than amplitude. The filter achieves sufficient attenuation in the frequency band that covers interference and minimal attenuation at 50/60 Hz, thus eliminating transient surges on the ground. The GTT technology incorporates a patented circuit with no moving parts or sensitive electronics, and thus does not pose any threat to intrinsic safety ground. The GTT is the first suppression device to be recognized by Underwriters Laboratories to be used directly on the ground line of electronic equipment to prevent disruptions in operation.

For more information, visit www.9corp.com.

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