Low power is relative

Everyone talks about low-power systems, but I have found that low power by itself is not a very good description. The problem is a lack of something to make a comparison. You can’t have low power if you haven’t defined high power, and this definition varies greatly with the application. Because embedded systems are so diverse, you must always consider the application before you try to apply generalities.

The porch light you leave on when you go out for the evening is typically 100 W. The little light you leave on 24/7 in your kid’s bedroom is 7 W. It is low power compared to the porch light and even one-third the power of an energy-conserving compact florescent at 23 W.

If people are willing to call a night-light that uses 7 W low power, why then does their embedded computer have to use less than 7 W? Besides being low power, the computer must have the latest x86 processor running at a gigahertz or more with a gigabyte of memory (the software group would like two gigs) plus Ethernet, serial ports, USB, video, SATA, and the list goes on. The reason for this disparity is the application. People aren’t comparing their computers to a porch light; they’re considering how their computers will be used in unique embedded applications.

The driving forces behind the power struggle are power source and heat dissipation. If you have a limited amount of either, you need a low-power system. If you’re plugging the system into the wall and operating in a laboratory environment, your standard for low power will be much higher than if you’re on a spacecraft using a small solar panel and batteries. Your power requirements will often be dictated by the operating environment. If it has to survive at +85 °C, a higher-power processor will require more cooling, thus driving the need for lower power. This is why you can talk to a scientist about a low-power space application that needs less than 7 W while also conversing with a truck operator in need of a low-power computer less than 100 W.

So what does all this have to do with the PC/104 Embedded Consortium? PC/104 architecture has the flexibility to provide low power and high performance. If you’re asking yourself “Does he mean 7 W or 100 W?” the answer is both. With specifications that cover ISA, PCI, and PCI Express, the PC/104 architecture addresses the spectrum of power requirements. These buses are available on the original 104 form factor coupled with larger EPIC and EBX form factors.

For absolute low power, many products with 386/486 class processors fit this requirement nicely. Newer processors such as AMD’s Geode LX and Intel’s Atom feature advanced power management that provides high performance with lower power. Global states, system states, device states, processor states, and performance states combine to give you the processing power when you need it and the power savings to keep average power low.

If you have not visited the PC/104 Consortium website at www.pc104.org lately, I encourage you to do so. It is fast becoming the portal for PC/104 information. You can keep abreast of the latest specifications for free, and the product section is significantly improved. You can search by specification, member company, product type, or keyword. Each product listing includes a product picture, description, hotlinks, and company contact info. The site lists many more products and companies than in the past, and they are easier to find. If your company does not have its products listed here, you are missing a great benefit of Consortium membership.

PC/104 Consortium 916-270-2016 info@pc104.org www.pc104.org