Power Electronics

Data Points

Portable Devices Accelerate Demand for Power Chips

Driven by increasing demands from portable electronic equipment, the worldwide power-management semiconductor market will expand significantly during the next few years, according to iSuppli. The El Segundo, Calif.-based market research firm also reports that worldwide revenue from shipments of power-management semiconductors will rise to $39.9 billion in 2011, a 59.6% increase from $24.98 billion in 2006. Semiconductors in this segment include voltage regulators, power-management ASICs, and application-specific standard products (ASSPs), rectifiers, thyristors and power transistors.

“As sales of portable products like portable media players (PMPs) and mobile handsets continue to rise, and the battery-life requirements for such devices continue to toughen, demand is rising for more sophisticated power-management solutions,” said Marijana Vukicevic, senior analyst for iSuppli. “This is a major factor behind the expected expansion of the power-semiconductor market over the next few years.”

To address this topic further, Vukicevic hosted a webinar titled “Power Demand in Portable Equipment” on Aug. 8. In this webinar, Vukicevic addressed several issues, such as which types of power-management semiconductors will command the highest sales growth in portable equipment in 2007 and beyond. Vukicevic also discussed which portable devices will generate the most demand growth for power semiconductors.

To request an archived version of the webinar, contact Jonathan Cassell at 408-654-1714, or see www.isuppli.com for more information.

EPA Finds Energy-Efficiency Opportunities for U.S. Servers and Data Centers

A new report by the Environmental Protection Agency (EPA) claims that data centers in the United States have the potential to save up to $4 billion in annual electricity costs through more energy-efficient equipment and operations, and the broad implementation of best management practices. The “Report to Congress on Server and Data Center Energy Efficiency” recommends priority efficiency opportunities and policies that can also lead to additional savings using state-of-the-art technologies and operations.

The report finds that data centers consumed about 60 billion kWh in 2006, which represented roughly 1.5% of total U.S. electricity consumption. That statistic is a result of a rapid growth in recent energy usage.

According to the EPA report, the energy consumption of servers and data centers has doubled in the past five years. Moreover, the EPA expects this usage to almost double again in the next five years to more than 100 billion kWh, which corresponds to about $7.4 billion annually in energy costs.

Another finding was that federal servers and data centers account for approximately 6 billion kWh (10%) of this electricity use, at a total electricity cost of about $450 million per year. However, the report also indicates that existing technologies and strategies could reduce typical server energy use by an estimated 25%, with even greater energy savings possible with advanced technologies.

In December 2006, Congress requested that the EPA develop the report to examine market trends in the growth and energy use of servers and data centers. The report complements the EPA's ongoing efforts to develop new energy-efficient specifications for data-center equipment, as well as explorations into a new Energy Star building benchmark for data centers that reflects whole-building operations.

For additional information and a copy of the report, see www.energystar.gov.

PMBus Working Groups Tailor Specs to Applications

In an effort to further define the Power Management Bus (PMBus) specifications as they are required in specific applications, the PMBus Implementers Forum has begun forming application-profile working groups. Specifically, these groups will address customer requirements for PMBus in ac-dc power supplies, microprocessor power supplies (VCORE) and point-of-load dc-dc converter applications.

These groups will work toward creating lists of application-required PMBus commands, while also establishing limits on parameters for those commands. In identifying commands that must be supported and setting limits on their values, the groups will enable chipmakers to develop compatible components for those applications.

New End-User Markets Drive Semiconductor Market Growth

A report by market research firm Frost & Sullivan (Palo Alto, Calif.) forecasts that the global market for discrete power semiconductors will rise from revenues of $10.49 billion in 2005 to an estimated $14.42 billion in 2009. Despite a lack of technological development for mature products such as thyristors, rectifiers and bipolar transistors, innovations in MOSFETs and IGBTs are contributing to the use of discrete power semiconductors in new applications, according to the firm.

“The growth of electronic content in automobiles, and the tremendous rise of communication and electronic gadgets, have a positive impact on the sales of discrete power semiconductors,” says Frost & Sullivan Senior Research Analyst Bonnie Varghese. “The industry has witnessed a complete makeover, and this will likely continue over the next few years.”

The increasing sales of consumer electronics, communication technology and automobiles, especially in the Asian market, drive the discrete power-semiconductor market. All of these applications combined contribute more than half of the discrete power revenues, states the firm.

Among thyristors, rectifiers and bipolar transistors, where technological advancements have been absent, the products remain undifferentiated, according to Frost & Sullivan. As a result, manufacturers have begun either abandoning these products or lowering prices to increase sales volumes and maintain revenues, which often results in negative growth or zero profits. Only a few industries invest in the research and development of rectifiers, the marketing firm reports.

“General-purpose rectifiers face a sharp decline, whereas ultrafast and Schottky rectifiers will likely achieve growth,” explains Varghese. “Despite a move toward rectifier function integration with other power semiconductors, this trend appears speculative as some end users claim integration has a negative impact on the efficiency of discretes.”

The firm notes that application and design engineers continuously improve the performance of MOSFETs and IGBTs by reducing drain-source resistance and offering low conduction losses, high power rating, faster switching speeds, low switching losses and smaller packaging sizes. These advances in performance result in a greater application range and decreasing prices.

For more information on “World Discrete Power Semiconductor Markets,” see www.semiconductors.frost.com.

U.S. Patents Address Coupled Inductor Innovations

The Center for Power Electronics Systems (CPES) has received two U.S. patents on power-management technologies that relate to the application or design of coupled inductors. Issued June 19, 2007, U.S. Patent #7,233,132 is titled “Current Sensing in Multiple Coupled Inductors by Time Constant Matching to Leakage Inductance” and was authored by Yan Dong, Ming Xu and Fred C. Lee. U.S. Patent #7,199,695 was issued April 3, 2007, and is titled “Coupled-Inductor Technique for Multi-phase VRs.” This patent was written by Jinghai Zhou, Fred C. Lee, Ming Xu and Yan Dong.

The patent on current sensing describes a technique for accurately sensing the magnitude of output current in coupled inductors. This technique is applicable in multiphase voltage regulators where feedback control of the regulators requires accurate and responsive sensing of output current.

With this sensing technique, an RC circuit is connected in parallel with the coupled inductor. The series-connected resistor and capacitor are selected such that their RC time constant is equal to an L/R time constant of Lk/DCR, where Lk is the leakage inductance and DCR is the ohmic resistance of the inductor. With the matching time constants, a sum of voltage on the capacitors is accurately proportional to a sum of currents flowing in the output inductors. The patent also describes a method for sensing current when an uncoupled center tap inductor is present.

The other patent describes a coupled inductor technique that may be applied in a multiphase buck or boost converter, or buck-boost converter, where an inductor is present in each phase. In this coupled inductor design, a magnetic core with a unique woven topology provides inverse coupling between the inductors.

The inductors can comprise straight conductors, because the magnetic core has the woven topology wrapped around each inductor. The advantage of this approach is that the inductors have a reduced electrical resistance, because they are straight and do not loop around the magnetic core. The lower resistance increases energy efficiency and improves the transient response of the circuit.

The magnetic core can comprise top and bottom portions that are magnetically connected. The inductors can comprise straight circuit-board traces, and the circuit board can have holes to accommodate the magnetic core. For more information about CPES Intellectual Property, contact Teresa Shaw at [email protected].

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