Coming in May in PET...

Power Management:

“Double Your Performance with an Interleaved Boost Converter”
By Ron Crews, National Semiconductor, Santa Clara, Calif.

There have been many articles describing the use of multi-phase buck converters, especially for high-performance point-of-load applications. However, all of the advantages of interleaving, such as higher efficiency and reduced input and output ripple, are also realized in the boost topology. Most of the controllers used in buck applications apply equally well when configured as an interleaved boost application. This article describes a two-phase boost converter using the LM5032 PWM controller.

Power Semiconductors:

“Beware of Maximum Power Specifications”
By Roger Stout, Senior Research Scientist, ON Semiconductor, Technology Development, Advanced Packaging, Phoenix

In this feature, the author explains in detail why a semiconductor device’s maximum power dissipation is situation dependent, and depends heavily on the thermal capabilities of the system in which the device is used. Armed with this knowledge, designers can avoid the confusion that often arises from misleading data sheet specifications.

Power Systems:

Testing a Li-ion battery charger using its natural load (a battery) is time-consuming, because the charging process can take an hour or more. The test time varies widely, according to whether you combine a fast-charge battery with a slow charger, or vice-versa, or something in between. In this feature, the authors describe an alternative to load testing with a real battery. The circuit described represents a simulated but realistic load.

EMC & Power Protection:

“Boosting Efficiency in Offline Power Converters”
By Michael O’Loughlin, Applications Engineer, Texas Instruments, Dallas

Power factor correction (PFC) pre-regulators in offline power converters greatly help the power company by reducing losses in the transmission lines as well as better utilize available line power. This benefit, however, does not come for free and has created many challenges for the power-supply designer. PFC pre-regulators make offline power converters less efficient, making it harder for the designer to meet no-load system power requirements. This article will review the benefits of PFC, as well as power-supply-control innovative techniques used to make these designs more efficient and conserve energy.

Power Design:

“Simple and Easy Power-OK indicator”
By Ted Salazar, Maxim Integrated Products, Sunnyvale, Calif.

Undervoltage/overvoltage indicators, called Power-OK indicators, can notify portable-equipment users when the battery voltage is too low or the battery is being overcharged. Though it’s not difficult to design a circuit for this purpose using a logic gate, comparators and other components, a simpler alternative is described by the author.

Executive Viewpoint:

“Are Open Standards Redefining Telecom Power?”
By Jim Bird, Systems Engineer for the Power Interface Products Group, Texas Instruments, Manchester, N.H.

In this feature, the author discusses how three standards — Advanced Telecommunications Computing Architecture (ATCA), AMC.0 by the PCI Industrial Computer Manufacturers Group (PICMG) and MTCA (MicroTCA) — are changing the way telecom systems are powered.

Online Exclusive on Lighting Power Management:

“Driving LED Backlights, RGB LEDs vs. White LEDs”
By Tomi Koskela, National Semiconductor, Santa Clara, Calif.

The liquid crystal display (LCD) backlight is a very important element that affects the quality of the displayed image. Typically, LCD backlight has been done with cold-cathode fluorescent lamps (CCFLs), but now LED technology is increasingly becoming the technology of choice in larger displays too. LED backlighting can be done with combination of red, green and blue (RGB) LEDs or with white LEDs. Choosing the right kind of backlight for the application depends on the size of the display, color reproduction requirements, power-efficiency requirements and system cost. This article discusses the most common methods, issues and future trends on driving LED backlighting.