Here comes USB 3.0

A standards group released specifications for a new Universal Serial Bus standard that could speed up data transfers between computers and devices such as digital cameras and flash drives.

The USB 3.0 specification increases bandwidth and transfers data between devices close to 10 times quicker than its predecessor, USB 2.0, said Jeff Ravencraft, president of the USB Implementers Forum (USB-IF) and senior technology strategist at Intel, during a speech at the USB Superspeed Developers Conference in San Jose, California.

USB ports are used to connect host devices, such as PCs, to other devices such as printers and storage drives. While USB 2.0 provides transfer rates that are enough for most devices today, USB 3.0 will be used in future devices that are more portable and as the use of multimedia applications such as video proliferates, Ravencraft said.

A flash drive based on USB 3.0 can move 1G byte of data to a host device in 3.3 seconds, compared to 33 seconds with USB 2.0, Ravencraft said. That means two full-length movies can be transferred from a portable USB drive to a PC in under a minute.

However, data transfer rates between USB 3.0 devices at booths at the conference seemed to reach about 3G bps (bits per second), which is lower than the 5G-bps transfer rates claimed by USB-IF.

Data overheads could keep raw data transfer speeds from reaching 5G bps, but the new specification is still a big improvement over USB 2.0, said Chuck Tefts, director of sales and marketing at Ellisys, which makes devices to test the USB 3.0 specification. As the specification is further developed and tested, those overheads may be eliminated, increasing data transfer rates, Tefts said.

The new specification adds better power-management features for charging devices and saving power, Ravencraft said. The power delivery envelope has increased, and connected-but-unused USB 3.0 devices can go into a virtual sleep mode.

The USB 3.0 specification also solves the problem of not recognizing battery-sapped devices, Ravencraft said. For example, the specification allows a host device to trickle down power to recognize battery-sapped devices like cell phones, which can then be charged. Devices like MP3 players rely on USB to recharge batteries.

Products with USB 3.0 support will likely enter the market in 2010, Ravencraft said. Flash-based mass storage devices may be first. Meanwhile, the specification has been finalized and is available to device manufacturers to test and implement.

Software needs to support the new protocol for devices to realize the transfer speeds of USB 3.0. Microsoft will support USB 3.0 devices in future Windows operating systems, said Fred Bhesania, program manager at Microsoft. The company is working on a software stack and intends to add USB 3.0 capabilities to the Windows OS in the future, Bhesania said. He did not specify which Windows versions will support USB 3.0.

The new standard is backwards-compatible, so new USB 3.0 devices will support USB 2.0 connections. About 2.5 billion USB-based products ship per year, Ravencraft estimated, so it is important to make the old standard work with new devices.