80 Million SuperSpeed Devices in 2011
By Greg Quirk, Mouser Electronics
USB is everywhere with over 6 billion devices connecting with USB worldwide. In the world of computers, peripherals, and mobile devices, USB inspires confidence as the most widely accepted, reliable form of connectivity out there – delivering speed, effortless charging, and plug-and-play simplicity.
Which brings us to USB 3.0(SuperSpeed). Although it has been a long time coming, the benefits it offers are definitely welcome. Finally in 2008, USB 3.0 was finalized. While it has been a few years since the introduction, it is starting to gain traction.
With close to 80 million USB 3.0 devices to ship in 2011, it is apparent that the consumer interest is there. One reason for the traction of USB 3.0, aside from the technical advantages and existing consumer familiarity with USB, is the openness of the connection. The xHCI specification was released in May 2010, allowing operating systems, including the open-source Linux community, to integrate the USB stack. Like Linux, USB is royalty free.
There are many advantages that USB 3.0 offers. The first, and most obvious, is the increased transfer speed, which gave USB 3.0 the nickname of SuperSpeed USB. While the theoretical top speed of nearly 5Gb/s is not easy to meet, most speed tests have resulted in anywhere from a 3x to 10x improvement over the previous version. In one test, it would take about 14 minutes to transfer 25GB of data over USB 2.0, while the same amount of information only took 4 minutes using USB 3.0.
This advancement is one of the key reasons for acceptance of the new USB standard. More devices are capable of storing more information, such as HD video and high megapixel pictures, or hard drives with larger capacity found in a standalone hard drives or a portable video players like the iPad. When transferring from one device to the other, the greater speed enabled by SuperSpeed USB saves the consumer a considerable amount of time.
In addition to the greater speed, there was a fundamental change in the way that data was transferred. Previously, the USB device would “poll” the computer to see if new data was trying to be transferred and prevented the computer from entering a low power state to conserve battery life. While this did not consume a significant amount of power, when using a laptop, every bit of battery life counts. Instead of this technique, SuperSpeed employs an asynchronous method of determining if data is available and will only turn on when you attempt to read or write to the connected device.
More power is available for USB devices so that they can charge faster. Unfortunately, this is still not sufficient to turn off the “not charging” indicator on the iPad without an included power driver, as the iPad requires 2.1A of power and USB 3.0 offers 0.9A.
In order to support the asynchronous mode, USB 3.0 includes an additional physical bus. This increases the number of connections from four wires to eight, which consists of two sets of transmit and receive wires. The new wires support the faster bandwidth goals of USB 3.0.
Not everything about USB 3.0 is an improvement over the previous version. The cable length and total distance have been decreased. While this may not be an issue for most consumer applications, it could potentially cause some concerns for commercial use – especially when it is not convenient to have the host machine close to the connected devices. However in those cases, people can weigh the speed benefits with the convenience, or they could turn to alternative methods, such as wireless technology.
While USB 2.0 is still the “standard” with about 2.5 billion devices released in 2010, more systems will be employing USB 3.0 in the future. The driving force for the adoption is the faster performance coupled with higher storage capacity. This in turn improves the HD recording capability of consumer products. However, smartphones that can take advantage of the improvements offered by USB 3.0 are not expected until 2013, at which time consumer acceptance will really take off. And with an expected 160 million smartphones to be sold in 2013, many of which are expected to utilize USB 3.0, that is a sizable number.
Greg Quirk has been a technical writer since 2004 focusing on semiconductor components, consumer devices and business trends. He has written numerous articles for industry publications and presented at technical conferences. His expertise has been sought by the financial community on multiple occasions to predict design-wins in popular consumer products.