Power Electronics

More Digital Design and Controversy in 2006

Last year, we were bombarded with news about competing industry alliances, attempts to meet the pending RoHS directives, and the continued expansion of manufacturing and design in China. However, none of these topics generated more controversy or excitement than digital power design.

This past year marked a turning point in the digital power saga. In previous years, there had been much discussion about the merits of digital power control, but few digital power solutions were being offered. (Primarion's VRM controllers and Power-One's Z-One point-of-load converters [POLs] and power managers come to mind as early entrees in the field.)

But then in 2005, there were several digital power product introductions. Texas Instruments, Silicon Laboratories, Zilker Labs and Primarion unveiled digital power controllers, which offered different approaches to implementing PWM controllers digitally and different levels of integration for building POLs. Meanwhile, power supply companies such as Artesyn Technologies, Delta and Astec Power introduced digitally controlled POLs. In addition, Power-One offered a “No-Bus” version of its Z-One digital POLs, which operated without external controllers or a system bus.

In tandem with these product announcements, there were the related standardization efforts to develop a standard for communications with digitally controlled power converters. Efforts began in 2004 with the proposal of the PMBus, and by January 2005, both DOSA and POLA — competing industry alliances — had endorsed the idea. Revision 1.0 of the standard was introduced in March, and as various power controllers and POLs were introduced over the course of the year, several specified support for PMBus commands.

However, the PMBus effort was not the only attempt to create a standard for digital power. Last summer, Power-One formed the Z-One Digital Power Alliance. The alliance consisted of C&D Technologies (a partner since 2004), which was second sourcing the Z-One digital POLs and power managers, and Atmel, which would second source chips used in the Z-One architecture. Although the Z-One Alliance was unveiled with little fanfare, the company has big plans for it. “It's always been our intention to make Z-One the industry standard for digital power,” says Dave Hage, president of Power-One. That approach to standardization means licensing Power-One's digital power technology to additional partners.

In light of all these product developments and industry collaboration activities, we would naturally expect to see more digital power product introductions in 2006. But don't take that for granted, because 2005 also marked the beginning of what may become lengthy legal battles over who owns the relevant intellectual property.

In the fall, Power-One brought suit against Artesyn and later Silicon Laboratories for alleged infringement of four of Power-One's digital power patents. The patents in question address fundamental aspects of digital power management, so the outcome of these lawsuits could have broad implications for an industry eager to develop and market digital power solutions. This suit is expected to be ongoing in 2006.

So, what happens in the courts could impact plans to introduce new digital power products this year. However, I don't believe these legal battles will affect the ongoing discussion of digital design and application issues at industry conferences and in the press. For example, in this magazine, we start off the new year with an article from Texas Instruments that examines digital control in battery management.

We also continue the industry debate over what constitutes digital design and how much digital content is necessary. In this month's Executive Viewpoint, Steve Pietkiewicz of Linear Technology argues that “Digital Power Is Mostly Analog” even in the most digital implementations of switching regulators. Pietkiewicz comments, “Many ‘digital power’ implementations are interesting technical achievements, but modern analog implementations actually perform better, in a smaller footprint.”

In the past, it's been difficult to assess such claims, but with several digital power controllers and modules now becoming available, designers can make real-world comparisons and come to their own conclusions.

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