New Processors Eliminate Fans

Advances in low-power microprocessors are making these devices more attractive to designers of embedded systems. The devices designed for portable products run far cooler than conventional chips, making it possible to design systems that run cool enough to operate without fans.

Products without fans meet demands in harsh environments such as industrial, where keeping dirt and other airborne materials away from sensitive electronics is important. Additionally, eliminating fans can help in medical and other noise-sensitive applications.

To meet these emerging needs, Transmeta Corp. ( recently unveiled its Crusoe Special Embedded (SE) line, which leverages the company's expertise in Intel-compatible devices that consume very little power. "In embedded systems, that power savings translates to less heat, which means you can use passive cooling for chips that run at up to 1 GHz," says Tom Lee, director of embedded business development at Transmeta.

Officially, the line isn't quite at 1 GHz. The fastest model runs at up to 933 MHz, though rounding up is not exactly rare for ICs. Other Crusoe SE versions have 667 and 800 MHz ratings. The line uses a power management technology called LongRun, which continuously optimizes processor frequency and voltage to keep power use and heat creation at low levels.

Lee explains that many of the competing processors designed specifically for embedded systems top out at around 400 MHz, and the faster chips in the Intel architecture draw more power and thus run much hotter. "When you go to Pentium IIIs, they take too much power," he says.

It isn't only electronics that benefit from the elimination of fans. "On the mechanical engineering side, enclosures can be simpler," Lee says. For example, MEs wouldn't have to worry about airflow, and eliminating fans can mean smaller enclosure sizes, he explains. Additionally, fans can be a factor in long-term reliability. "In a lot of environments, you don't want the fan sucking stuff in, as on a factory floor," Lee says. While the MTBF can be four years for a fan, according to Lee, he notes that the Crusoe SE should run for 10 years at 100C junction temperatures without failure.

Crusoe parts come with upgraded code morphing software, which provides real time performance while also providing x86 compatibility. The Intel Northbridge link between processor and peripherals is also included on the IC, helping keep board size down.

Among the applications being targeted are point-of-sale terminals, industrial automation, process control, and special applications such as systems that measure fuel at a gas station and send inventory status reports to the fuel distribution center. In some uses, power economies alone can mean significant savings for end users, particularly those who have many units operating over long periods. "If you've got a lot of POS terminals running nonstop, dropping from a 20-50W processor to a 6W one brings a pretty substantial savings," Lee says.

As these high-speed products make their way into embedded systems, it's also permitting a change from hardware-based architectures to systems based on software. Instead of using fixed hardware designs to run specialized algorithms, design engineers can use flexible software architectures. "With this much processing power, it's becoming possible to solve a problem with general purpose hardware," Lee adds.

Pricing starts at about $50 for volume shipments of the 667 MHz version. Support comes from vendors.

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