USB 3.0 is ready to bring a fundamental shift to the PC and storage markets, and a significant group of established industry leaders are moving quickly to realize these changes. USB 3.0 delivers a new level of performance without changing the USB connector's form factor and with full backward compatibility in all other respects.
In addition to meeting storage requirements, USB 3.0 is suited for a wide range of connectivity applications. Also known as SuperSpeed USB, USB 3.0 delivers several enhancements:
- Increased bandwidth—up to 5 Gbits/s full duplex (compared to 480 Mbits/s simplex for USB 2.0)
- Better power management
- Ability of the host to deliver more power to devices, enabling applications such as USB-rechargeable batteries, LED lighting, etc.
- Ability of the host to identify devices faster
- New protocols that make data handling more efficient
When used in consumer devices, USB 3.0 solves a problem that users have had with USB 2.0—failure to recognize devices whose batteries are depleted. A host device can trickle down power via USB 3.0 to recognize devices such as cell phones whose batteries have gone dead.
Because USB 3.0 enables external drives to achieve data transfers as fast as internal PC drives, users will take advantage of external storage more often than in the past, particularly with the ability of USB 3.0 to download video. For example, HD TV and movies can be downloaded in seconds, limited only by the storage device's transfer rate. A flash drive using USB 3.0 can move 1 Gbyte of data to a host device in 3.3 seconds, compared to 33 seconds with USB 2.0 (according to the USB Implementers' Forum).
For storage applications, the relationship between USB and Serial ATA (SATA) is particularly interesting, given their status as the interfaces of choice for external and internal storage, respectively. With USB 3.0 now supporting disk drives' highest transfer rates, it offers the opportunity to use commonly available SATA drives as external USB 3.0 peripherals. Adding a USB 3.0 interface to a SATA drive is straightforward through the use of a device that bridges USB 3.0 to SATA.
Of the interfaces competing for external storage applications in recent years, USB, External SATA (eSATA), and FireWire have each claimed significant numbers of wins. SATA has replaced all other interfaces for internal drive connectivity in consumer PCs. Since its introduction in 2004, eSATA has challenged USB 2.0 and FireWire for external storage applications. eSATA transfers data to and from external devices at the same rate supported by SATA for internal drives. Specifically, the eSATA interface supports data rates up to 3 Gbits/s. Even with actual rates reduced by encoding overhead, eSATA's data rate is more than enough for the fastest hard drives, which can transfer data at about 120 Mbytes/s.
This performance has enabled eSATA, with its low CPU overhead, to take market share from both USB 2.0 and FireWire, even though eSATA is useful only for storage applications. At 5 Gbits/s full duplex, USB 3.0 is faster than eSATA and FireWire 800, which achieves almost 800 Mbits/s full duplex. eSATA's 3-Gbit/s rate is simplex, in contrast to the full duplex provided by USB 3.0, and USB 3.0 also includes optional provisions for transferring out-of-order data optimized for disk drive seeks.
Spurred by the increasing resolution and storage capability of consumer electronic devices, along with the wider availability of media via broadband Internet connections, users will want a faster transfer capability to simplify downloading, storing and sharing large amounts of multi-media content. USB 3.0 will play a key role in providing the simple connectivity consumers want and drive the need for faster transfer methods. Fujitsu's MB86C30A USB 3.0/SATA bridge device offers an easy way for developers to adapt SATA drives for USB 3.0.
About the author
Daisuke “Davy” Yoshida is been the director of business development for Fujitsu Microelectronics America's Embedded Platform Solutions Business Group. He focuses on developing semiconductor solutions with partners, launching early-stage advanced products, and researching emerging markets. Yoshida holds a BS degree in Economics from Keio University, Tokyo, Japan, and an MBA from University of London, Imperial College.