Digital Power: Still Looking For A Killer Application

Apr 18, 2007 10:54 AM
By Alan Elbanhawy, director in the Advanced Power System Center, Fairchild Semiconductor International, San Jose, Calif.

If that happens, the technology will have matured to a point where the price/performance value proposition is such that digital technology could easily be adopted in other applications. Having conquered PCs, digital power could then be deployed in the telecom industry’s point-of-load (POL) converters and 48-V isolated dc-dc converters, as well as countless ac-dc converters in all shapes and forms.

However, a paradigm shift in the business model of the PWM controller manufacturers must be achieved to pave the way toward such a migration. That is to say, the chipmakers must provide a digital solution for a given application that enables a totally new power system or subsystem. Moreover, the digital solution must greatly expand the domain of the application, providing breakthrough features that are uncommon or even unknown in analog power systems.

These features range from the simple to the complex. Digital technology could perform simple tasks such as power sequencing and communicating power-supply status to a central computer. The technology could also implement more demanding functions like fault diagnosis and even calculating the optimum control-loop parameters on the fly.

The latter capability could be applied in the production environment to a mass-produced power converter to eliminate the unpredictable effects of the converter’s various error-prone components such as inductors, capacitors and error amplifiers. In other words, digital techniques could compensate for the various component tolerances, which produce a statistical distribution of component values when a power converter design goes into high-volume production.

There’s no limit to the number of ways these digital-enabled features may be combined to create power systems that can accommodate the demanding power requirements of the today’s most sophisticated systems as well as those of the future. This clearly brings us back to the concept of the killer application.

Excluding the supremely sophisticated modern military systems, there are still no large applications in the tens of millions of units per year that demand such advanced power systems to achieve success. The reason is partly because power systems have been the exclusive domain of the analog discipline because analog is the most cost-effective way to implement these systems. Design organizations still choose a solution exclusively based on its cost, assuming that it meets the basic design specifications.

Ultimately, digital power solutions will take off if — and only if — they can offer the same or better performance than analog for lower price or if the system is so complicated that the digital approach is the only feasible solution to meet the target price and performance demands of the end users like the giant OEMs.

1. Elbanhawy, Alan, "Going Against the Grain: Digital Power Looking For a Killer Application," 2005 Digital Power Forum, Boston.

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