Technology with the Environment in Mind

Making USB a More Energy-Efficient Interconnect

Barnes Cooper, Mobile Platforms Group, Intel Corporation
Paul Diefenbaugh, Corporate Technology Group, Intel Corporation
Jim Kardach, Mobile Platforms Group, Intel Corporation

Index words: USB, low power, power friendly devices, platform power management

Citations for this paper. Cooper, B.; Diefenbaugh, P.; Kardach, J. "Making USB a More Energy-Efficient Interconnect." Intel Technology Journal. http://www.intel.com/technology/itj/2008/
v12i1/2-usb/1-abstract.htm (February 2008).

ABSTRACT

The '64 Mustang is a classic: a car that people still talk and reminisce about 44 years on. Do you mess with success and change a winning formula? No, but you do update a design to fix weaknesses in the original (better audio, air-conditioning, reliability, etc.) and to address new consumer desires as the market changes (efficient engines to address fuel economy, catalytic converters to address the need for a cleaner environment, etc.).

The Universal Serial Bus (USB) is a classic of the computer world. It was introduced in 1996 and is now a ubiquitous computer interface. When it was developed in the mid '90s it was targeted for mainstream computers of the time, optimized primarily for consumer ease of use and low device cost. Around 2002, USB 2.0 was introduced offering a performance bump to 480 Mbps; again optimized to meet similar criteria.

Although many characteristics of the USB are top-notch, its impact on platform power consumption has been downright abysmal. While power consumption was not an important criterion of its original design, the USB has become a defacto feature for battery-powered platforms where low power is key. In addition, global concerns over energy consumption and carbon emissions have made energy efficiency an important market requirement even for desktop and server systems [1]. Therefore, like the classic Mustang, it's time to overhaul the USB in a manner that preserves the goodness which has helped make it such a successful interconnect.

In this paper we first outline the USB power issues and look at their impact on mobile platforms. We then discuss ways of resolving these issues. Although the focus here is clearly on notebook systems, most issues and solutions apply to other systems as well.

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