USB 3.0
USB 3.0 is the second major revision of the Universal Serial Bus
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 (USB) standard for computer connectivity.

USB 3.0 has transmission speeds of up to 5 Gbit/s, which is 10 times faster than USB 2.0 (480 Mbit/s). USB 3.0 significantly reduces the time required for data transmission, reduces power consumption, and is backwards compatible with USB 2.0. The USB 3.0 Promoter Group announced on 17 November 2008 that the specification of version 3.0 had been completed and had made the transition to the USB Implementers Forum
USB Implementers Forum
The USB Implementers Forum is a non-profit organisation to promote and support the Universal Serial Bus. Its main activities are the promotion and marketing of USB, Wireless USB, USB On-The-Go, and the maintenance of the specifications, as well as a compliance program.It was formed in 1995 by the...

 (USB-IF), the managing body of USB specifications. This move effectively opened the specification to hardware developers for implementation in future products.

The first USB 3.0 consumer products were announced and shipped by Buffalo Technology in November 2009, while the first certified USB 3.0 consumer products were announced 5 January 2010, at the Las Vegas Consumer Electronics Show
Consumer Electronics Show
The International Consumer Electronics Show is a major technology-related trade show held each January in the Las Vegas Convention Center, Las Vegas, Nevada, United States. Not open to the public, the Consumer Electronics Association-sponsored show typically hosts previews of products and new...

 (CES), including two motherboards by ASUS
ASUSTeK Computer Incorporated is a multinational computer technology and consumer electronics product manufacturer headquartered in Taipei, Taiwan. Its product range includes motherboards, desktops, laptops, monitors, tablet PCs, servers and mobile phones...

 and Gigabyte Technology
Gigabyte Technology
Gigabyte Technology Co., Ltd. is a Taiwan-based manufacturer of computer hardware products best known for its motherboards. The company is publicly held and traded on the Taiwan Stock Exchange .-Company:...


Manufacturers of USB 3.0 host controllers include, but are not limited to, Renesas Electronics
Renesas Electronics
is a Japanese semiconductor manufacturer. It is based in Tokyo and has manufacturing, design and sales operations in around 20 countries. Renesas is one of the world's largest manufacturers of semiconductor systems for mobile phones and automotive applications. It is the world's largest...

, Fresco Logic, Asmedia, Etron, VIA Technologies
VIA Technologies
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...

, Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...

, a Japanese multinational IT company, has its headquarters in Minato, Tokyo, Japan. NEC, part of the Sumitomo Group, provides information technology and network solutions to business enterprises, communications services providers and government....

 and Nvidia
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...

. As of November 2010, Renesas was the only company to have passed USB-IF certification, although Fresco Logic has now also passed USB-IF certification. Motherboards for Intel's Sandy Bridge
Sandy Bridge
Sandy Bridge is the codename for a microarchitecture developed by Intel beginning in 2005 for central processing units in computers to replace the Nehalem microarchitecture...

 processors have been seen with Asmedia and Etron host controllers as well. On October 28, 2010 Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

 released the HP Envy
HP Envy
The HP ENVY series is a line of high performance laptops manufactured and sold by Hewlett-Packard, which was launched on October 15, 2009 as two models, the Envy 13 and the Envy 15...

 17 3D featuring a Renesas USB 3.0 Host Controller several months before some of their competitors. AMD is working with Renesas to add its USB 3.0 implementation into its chipsets for its 2011 platforms. At CES2011 Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...

 unveiled a laptop called "Toshiba Qosmio X500" that included USB 3.0 and Bluetooth 3.0, and a new series of Sony VAIO laptops that will include USB 3.0. As of April 2011 the Inspiron and Dell XPS series are available with USB 3.0 ports.

Apple Inc. is the only major computer manufacturer without USB 3.0 equipped computers as of August 2011, opting to use another standard called Thunderbolt instead.

Architecture and features

In USB 3.0 dual-bus architecture is used to allow both USB 2.0 (HIGH Speed/LOW Speed/FULL Speed) and USB 3.0 (Super Speed) operations to take place simultaneously, thus providing backward compatibility. Connections are such that they also permit forward compatibility, that is, run USB 3 devices on USB 2.0 ports. The structural topology is the same, consisting of a tiered star topology with a root hub at level 0 and hubs at lower levels to provide bus connectivity to devices.

Data transfer and synchronization

The SuperSpeed transaction is initiated by the host making a request followed by a response from the device. The device either accepts the request or rejects it. If accepted then device sends data or accepts data from the host. If the endpoint is halted, the device shall respond with a STALL handshake. If there is lack of buffer space or data, it responds with a Not Ready (NRDY) signal to tell the host that it is not able to process the request. When the device is ready then, it will send an Endpoint Ready (ERDY) to the host which will then reschedule the transaction.

The use of unicasting and the limited multicasting of packets, combined with asynchronous notifications, enables links that are not actively passing packets to be put into reduced power states, allowing for better power management.

Data encoding

All data is sent as a stream of 8-bits which are scrambled and then converted into 10-bit format. This helps to reduce electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...

 (EMI). The exactly opposite process is carried out at the receiving end. Scrambling is implemented using a free running Linear Feedback Shift Register (LFSR). The LFSR is reset whenever a COM symbol is sent or received.

The "SuperSpeed" bus, which provides a fourth transfer mode at 5.0 Gbit/s. The raw throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (0.4 GB/s or 400 MB/s), or more.

Adding to existing equipment

USB 3.0 support can be added to existing laptop computers with only USB 2.0 and Expresscard
ExpressCard is an interface to allow peripheral devices to be connected to a computer, usually a laptop computer. Formerly called NEWCARD, the ExpressCard standard specifies the design of slots built into the computer and of cards which can be inserted into ExpressCard slots. The cards contain...

 support by using an Expresscard-to-USB 3.0 adapter to supply USB 3.0 signal support. Although the PCI Express port that the Express card connects cannot supply power of itself, the Express card and hence the USB 3 ports nevertheless derive power from the USB 2 port that it additionally connects to as part of the interface. If the express card has more than one USB 3 port then only 100mA is available from each port. Additional power for multiple ports may be derived in the following ways:
  • Some Expresscard-to-USB 3.0 adapters may connect by a cable to an additional USB 2.0 port on the computer, which supplies additional power.
  • The Expresscard may have a socket for an external power supply.
  • If the external device has an appropriate connector, it can be powered by an external power supply.

USB 3.0 support can be added as an expansion card to a desktop motherboard with PCI Express
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...

. (Similar cards are available for the older PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...

 standard, but few are available and they are more expensive.) If faster connections to storage devices are the reason to consider USB 3.0, an alternative is to use instead storage devices using eSATAp
In computing, eSATAp is a high speed connection for external storage devices. It is a combination of serial port connectors into which an eSATAp, eSATA or USB devices can be plugged...

 and add an inexpensive bracket adding an eSATAp port to the motherboard. Some external drives support both USB (2.0 or 3.0) and eSATAp with an exchangeable adapter, so the same drive can be used with a USB 3.0 laptop. To ensure compatibility between motherboards and peripherals, all USB-certified devices must be approved by the USB Implementers Forum
USB Implementers Forum
The USB Implementers Forum is a non-profit organisation to promote and support the Universal Serial Bus. Its main activities are the promotion and marketing of USB, Wireless USB, USB On-The-Go, and the maintenance of the specifications, as well as a compliance program.It was formed in 1995 by the...

 (USB-IF). At least one complete end-to-end test system for USB 3.0 designers is on the market.
On 5 January 2010, USB-IF announced the first two certified USB 3.0 motherboards, one by Asus and one by Gigabyte. Previous announcements included Gigabyte's October 2009 list of seven P55 chipset USB 3.0 motherboards, and an ASUS motherboard that was cancelled before production.

Commercial controllers were expected to enter into volume production in the first quarter of 2010. On 14 September 2009, Freecom
Freecom is a German manufacturer of computer peripherals. Its products include USB hard disks , USB flash drives, USB DVB-T television receivers and data recovery service. The company was founded in 1989. The President and CEO is Dick C. Hoogerdijk, Managing Director is Axel Lucassen.-External...

 announced a USB 3.0 external hard drive. On January 4, 2010, Seagate
Seagate Technology
Seagate Technology is one of the world's largest manufacturers of hard disk drives. Incorporated in 1978 as Shugart Technology, Seagate is currently incorporated in Dublin, Ireland and has its principal executive offices in Scotts Valley, California, United States.-1970s:On November 1, 1979...

 announced a small portable HDD with PC Card targeted for laptops (or desktop with PC Card slot addition) at the CES in Las Vegas Nevada.

Drivers are under development for Windows 7, but support was not included with the initial release of the operating system. However, drivers are available for Windows through manufacturer websites. The Linux kernel
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....

 has supported USB 3.0 since version 2.6.31, which was released in September 2009.

Windows 8
Windows 8
Windows 8 is the codename for the next version of the Microsoft Windows computer operating system following Windows 7. It has many changes from previous versions. In particular it adds support for ARM microprocessors in addition to the previously supported x86 microprocessors from Intel and AMD...

 will have inbuilt support for USB 3.0.

Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...

 decided not to support USB 3.0 until 2011, which will slow down mainstream adoption. These delays may be due to problems in the CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

 manufacturing process, a focus to advance the Nehalem platform, a wait to mature all the 3.0 connections standards (USB 3.0, PCIe 3.0, SATA 3.0) before developing a new chipset, or a tactic by Intel to boost its new Thunderbolt interface. Current AMD
Advanced Micro Devices
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...

 road maps indicate that the new southbridges released in the beginning of 2010 will not support USB 3.0.

Speed issues

There have been many reports of USB 3.0 equipment only transferring data at USB 2.0 speed, usually with a message "This USB Mass Storage Device can transfer information faster if you connect it to a Super-Speed USB 3.0 port". This has been due to several causes, including drivers, certain cables specified as USB 3.0 (problems disappeared when a different cable was used), order of starting equipment, equipment needing to be disconnected and reconnected, and overclocked computers.


A USB 3.0 Standard-A receptacle accepts either a USB 3.0 Standard-A plug or a USB 2.0 Standard-A plug. Conversely, it's possible to plug USB 3.0 Standard-A plug into a USB 2.0 Standard-A receptacle. The Standard-A is used for connecting to the computer port.

The connector has the same physical configuration as its predecessor but with more pins for USB 3.0. The VBUS, D-, D+, and GND pins are required for USB 2.0 support, while for USB 3.0 Standard-A connector, five more pins are included–two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer, that support dual simplex SuperSpeed signaling; while the GND_DRAIN pin is for drain wire termination, and to control EMI and maintain signal integrity.
Since USB 2.0 and USB 3.0 ports may coexist on the same machine and look similar, the USB 3.0 connector is blue (Pantone
Pantone Inc. is a corporation headquartered in Carlstadt, New Jersey, USA. The company is best known for its Pantone Matching System , a proprietary color space...

 300C) in colour.

USB 3.0 Standard-A and Standard-B
Pin Color Signal name
('A' connector)
Signal name
('B' connector)
1 Red VBUS
2 White D−
3 Green D+
4 Black GND
5 Blue StdA_SSRX− StdA_SSTX−
6 Yellow StdA_SSRX+ StdA_SSTX+
7 Shield GND_DRAIN
8 Purple StdA_SSTX− StdA_SSRX−
9 Orange StdA_SSTX+ StdA_SSRX+
Shell Shell Shield

USB 3.0 Powered-B
3 D+
4 GND Ground for Power Return
5 StdB_SSTX- Superspeed transmitter differential pair
6 StdB_SSTX+
7 GND_DRAIN Ground for signal return
8 StdB_SSRX- Superspeed receiver differential pair
9 StdB_SSRX+
10 DPWR Power provided by device
11 DGND Ground return to DPWR
Shell Shield Connector metal

See also

  • Computer bus
  • List of computer peripheral bus bit rates
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