USB 3.0, released in November 2008, is the third major version of the

Universal Serial Bus Universal Serial Bus (USB) is an technical standard, industry standard that establishes specifications for cables, connectors and communication protocol, protocols for connection, communication and power supply (Interface (computing), interfa ...

(USB) standard for interfacing computers and electronic devices. Among other improvements, USB 3.0 adds the new transfer rate referred to as ''SuperSpeed USB'' (SS) that can transfer data at up to 5

Gbit/s In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mul ...

(500

MB/s In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

after encoding overhead), which is about 10 times faster than Hi-Speed (maximum for USB 2.0 standard). It is recommended that manufacturers distinguish USB 3.0 connectors from their USB 2.0 counterparts by using blue color for the Standard-A receptacles and plugs, and by the initials ''SS''. USB 3.1, released in July 2013, is the successor standard that replaces the USB 3.0 standard. USB 3.1 preserves the existing ''SuperSpeed'' transfer rate, giving it the new label ''USB 3.1 Gen 1'', while defining a new ''SuperSpeed+'' transfer mode, called ''USB 3.1 Gen 2'' which can transfer data at up to 10 Gbit/s over the existing USB3-type-A and

USB-C USB-C (properly known as USB Type-C) is a 24-pin USB connector system with a rotationally symmetrical connector. The designation C refers only to the connector's physical configuration or form factor and should not be confused with the conn ...

connectors (1200 MB/s after encoding overhead, more than twice the rate of USB 3.0). USB 3.2, released in September 2017, replaces the USB 3.1 standard. It preserves existing USB 3.1 ''SuperSpeed'' and ''SuperSpeed+'' data modes and introduces two new ''SuperSpeed+'' transfer modes over the

connector using two-lane operation, with data rates of 10 and 20 Gbit/s (1200 and 2400 MB/s after encoding overhead). This specification has been renamed to reflect the evolution of "generations" of USB standards (i.e.: USB3.2Gen1 is "SuperSpeed", USB3.2Gen2 is also "SuperSpeed", but 2x faster, USB3.2Gen2x2 is also marketed as "SuperSpeed" but is 4x faster than 3.2Gen1). Nomenclature has been broadly criticized by both experts in the industry and the public at large for its confusing revisions not reasonably or appropriately reflecting the marketing messages that the guidelines prescribe in the standard specification, which is published at usb.org

Overview

The USB 3.0 specification is similar to USB 2.0, but with many improvements and an alternative implementation. Earlier USB concepts such as endpoints and the four transfer types (bulk, control,

isochronous A sequence of events is isochronous if the events occur regularly, or at equal time intervals. The term ''isochronous'' is used in several technical contexts, but usually refers to the primary subject maintaining a constant period or interval ( ...

and interrupt) are preserved but the protocol and electrical interface are different. The specification defines a physically separate channel to carry USB 3.0 traffic. The changes in this specification make improvements in the following areas: * Transfer speed USB 3.0 adds a new transfer type called SuperSpeed or SS, 5 Gbit/s (electrically, it is more similar to

PCI Express 2.0 PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common mo ...

and

SATA SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard to ...

than USB 2.0) * Increased bandwidth USB 3.0 uses two unidirectional data paths instead of only one: one to receive data and the other to transmit * Power management U0 to U3 link power management states are defined * Improved bus use a new feature is added (using packets NRDY and ERDY) to let a device asynchronously notify the host of its readiness, with no need for polling * Support for rotating media the bulk protocol is updated with a new feature called Stream Protocol that allows a large number of logical streams within an Endpoint USB 3.0 has transmission speeds of up to 5 Gbit/s or 500 MB/s, about ten times faster than USB 2.0 (0.48 Gbit/s) even without considering that USB 3.0 is

full duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

whereas USB 2.0 is

half duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

. This gives USB 3.0 a potential total bidirectional bandwidth twenty times greater than USB 2.0. Considering flow control, packet framing and protocol overhead, applications can expect 450 MB/s of bandwidth.

Architecture and features

In USB 3.0, dual-bus architecture is used to allow both USB 2.0 (Full Speed, Low Speed, or High Speed) and USB 3.0 (SuperSpeed) operations to take place simultaneously, thus providing

backward compatibility Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially ...

. 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 a host request, followed by a response from the device. The device either accepts the request or rejects it; if accepted, the device sends data or accepts data from the host. If the endpoint is halted, the device responds 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, sends an Endpoint Ready (ERDY) to the host which then reschedules the transaction. The use of

unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...

and the limited amount of

multicast In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...

packets, combined with asynchronous notifications, enables links that are not actively passing packets to be put into reduced power states, which allows better power management.

Data encoding

The ''"SuperSpeed"'' bus provides for a transfer mode at a nominal rate of 5.0 Gbit/s, in addition to the three existing transfer modes. Accounting for the encoding overhead, the raw data throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (400 MB/s) or more in practice. All data is sent as a stream of eight-bit (one-byte) segments that are scrambled and converted into 10-bit symbols via

8b/10b encoding In telecommunications, 8b/10b is a line code that maps 8-bit words to 10-bit symbols to achieve DC balance and bounded disparity, and at the same time provide enough state changes to allow reasonable clock recovery. This means that the dif ...

; this helps the receiver to decode correctly even in the presence of

electromagnetic interference Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrosta ...

(EMI). Scrambling is implemented using a free-running

linear feedback shift register In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a s ...

(LFSR). The LFSR is reset whenever a COM symbol is sent or received. Unlike previous standards, the USB 3.0 standard does not specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires, the maximum practical length is .

Power and charging

As with earlier versions of USB, USB 3.0 provides power at 5 volts nominal. The available current for low-power (one unit load) SuperSpeed devices is 150 mA, an increase from the 100 mA defined in USB 2.0. For high-power SuperSpeed devices, the limit is six unit loads or 900 mA (4.5 W)—almost twice USB 2.0's 500 mA. USB 3.0 ports may implement other USB specifications for increased power, including the

USB Battery Charging Specification The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of t ...

for up to 1.5 A or 7.5 W, or, in the case of USB 3.1, the

USB Power Delivery Specification The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of ...

for charging the host device up to 100 W.

Availability

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 The USB Implementers Forum (USB-IF) is a nonprofit organization created to promote and support USB (Universal Serial Bus). Its main activities are the promotion and marketing of USB, Wireless USB, USB On-The-Go, and the maintenance of the speci ...

(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 Melco Holdings Inc. is a family business founded by Makoto Maki in 1975 and is located in Japan. The company's most recognizable brand is Buffalo Inc. Buffalo Inc. is currently one of the 16 subsidiaries of Melco Holdings Inc., initially found ...

in November 2009, while the first certified USB 3.0 consumer products were announced on 5 January 2010, at the Las Vegas

Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event typi ...

(CES), including two motherboards by Asus and

Gigabyte Technology Gigabyte Technology (branded as GIGABYTE or sometimes GIGA-BYTE; formally GIGA-BYTE Technology Co., Ltd.) is a Taiwanese manufacturer and distributor of computer hardware. Gigabyte's principal business is motherboards. It shipped 4.8 million moth ...

. Manufacturers of USB 3.0 host controllers include, but are not limited to,

Renesas Electronics is a Japanese semiconductor manufacturer headquartered in Tokyo, Japan, initially incorporated in 2002 as Renesas Technology, the consolidated entity of the semiconductor units of Hitachi and Mitsubishi excluding their dynamic random-access memo ...

, Fresco Logic,

ASMedia ASMedia Technology Inc. () is a Taiwanese integrated circuit design company owned by Asus. It produces designs for USB, PCI Express and SATA controllers. Excluding the X570 chipset, all of the AM4 chipsets for AMD's Zen Zen ( zh, t=� ...

, Etron,

VIA Technologies VIA Technologies Inc. (), is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory. It was the world's largest independent manufacturer of motherboard chipsets. As a fabless semiconductor company, VIA c ...

Texas Instruments Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globall ...

NEC is a Japanese multinational information technology and electronics corporation, headquartered in Minato, Tokyo. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It provides IT and network solu ...

and

Nvidia Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as VIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as VIDIA with a large italicized lowercase "n" on products from the mid 1990s to ...

. As of November 2010, Renesas and Fresco Logic have passed USB-IF certification. Motherboards for

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...

Sandy Bridge Sandy Bridge is the codename for Intel's 32 nm microarchitecture used in the second generation of the Intel Core processors (Core i7, i5, i3). The Sandy Bridge microarchitecture is the successor to Nehalem and Westmere microarchitecture. ...

processors have been seen with Asmedia and Etron host controllers as well. On 28 October 2010,

Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

released the

HP Envy The HP Envy (stylized as HP ENVY) is a line of consumer-oriented high-end laptops, desktop computers and printers manufactured and sold by HP Inc. They started as a high-end version of the HP Pavilion line. History HP originally launched the ...

17 3D featuring a Renesas USB 3.0 host controller several months before some of their competitors.

AMD Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufact ...

worked with Renesas to add its USB 3.0 implementation into its chipsets for its 2011 platforms. At CES2011,

Toshiba , commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure syste ...

unveiled a laptop called "

Toshiba Qosmio The Qosmio series (dynabook Qosmio in Japan) was Toshiba's consumer-marketed line of high performance desktop replacement laptops. The laptop was first released on July 25, 2004 as the E15-AV101 with a 1.7 GHz Intel Pentium M CPU, 512 megaby ...

X500" that included USB 3.0 and

Bluetooth 3.0 Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limit ...

, and

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...

released a new series of Sony VAIO laptops that would include USB 3.0. As of April 2011, the

Inspiron The Inspiron ( , formerly stylized as inspiron) is a line of consumer-oriented laptop computers, desktop computers and all-in-one computers sold by Dell. The Inspiron range mainly competes against computers such as Acer's Aspire, Asus' Tran ...

and

Dell XPS Dell XPS ("eXtreme Performance System") is a line of consumer-oriented high-end laptop and desktop computers manufactured by Dell. The XPS mainly competes against computers such as Acer's Aspire, HP's Pavilion and Envy, Lenovo's X1, Samsung's ...

series were available with USB 3.0 ports, and, as of May 2012, the

Dell Latitude The Dell Latitude series is a line of laptop computers manufactured and sold by American company Dell. It is a business-oriented line, aimed at corporate enterprises, healthcare, government, and education markets; unlike the Inspiron series, wh ...

laptop series were as well; yet the USB root hosts failed to work at SuperSpeed under Windows 8.

Adding to existing equipment

Additional power for multiple ports on a laptop PC 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 An AC adapter or AC/DC adapter is a type of external power supply, often enclosed in a case similar to an AC plug. Other common names include wall wart, power brick, wall charger, and power adapter. Adapters for battery-powered equipment may ...

. * USB 3.0 port provided by an ExpressCard-to-USB 3.0 adapter may be connected to a separately-powered USB 3.0 hub, with external devices connected to that USB 3.0 hub. On the motherboards of desktop PCs which have

PCI Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common m ...

(PCIe) slots (or the older PCI standard), USB 3.0 support can be added as a PCI Express

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus sl ...

. In addition to an empty PCIe slot on the motherboard, many "PCI Express to USB 3.0" expansion cards must be connected to a power supply such as a

Molex Molex LLC is a manufacturer of electronic, electrical, and fiber optic connectivity systems. Molex offers over 100,000 products across a variety of industries, including data communications, medical, industrial, automotive and consumer electroni ...

adapter or external power supply, in order to power many USB 3.0 devices such as mobile phones, or external hard drives that have no power source other than USB; as of 2011, this is often used to supply two to four USB 3.0 ports with the full 0.9 A (4.5 W) of power that each USB 3.0 port is capable of (while also transmitting data), whereas the PCI Express slot itself cannot supply the required amount of power. If faster connections to storage devices are the reason to consider USB 3.0, an alternative is to use

eSATAp In computing, eSATAp (also known as Power over eSATA, Power eSATA, eSATA/USB Combo, eSATA USB Hybrid Port/EUHP) is a combination connection for external storage devices. An eSATA or USB device can be plugged into an eSATAp port. The socket ...

, possibly by adding an inexpensive expansion slot bracket that provides an eSATAp port; some external hard disk drives provide both USB (2.0 or 3.0) and eSATAp interfaces. To ensure compatibility between motherboards and peripherals, all USB-certified devices must be approved by the

(USB-IF). At least one complete end-to-end test system for USB 3.0 designers is available on the market.

Adoption

The USB Promoter Group announced the release of USB 3.0 in November 2008. On 5 January 2010, the

USB-IF The USB Implementers Forum (USB-IF) is a nonprofit organization created to promote and support USB (Universal Serial Bus). Its main activities are the promotion and marketing of USB, Wireless USB, USB On-The-Go, and the maintenance of the speci ...

announced the first two certified USB 3.0 motherboards, one by ASUS and one by Giga-Byte Technology. 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 FreeDOS (formerly Free-DOS and PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running legacy software and supporting embedded systems. FreeDOS ca ...

announced a USB 3.0 external hard drive. On 4 January 2010, Seagate announced a small portable HDD bundled with an additional USB 3.0 ExpressCard, targeted for laptops (or desktops with ExpressCard slot addition) at the CES in Las Vegas Nevada. The

Linux kernel mainline The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...

contains support for USB 3.0 since version 2.6.31, which was released in September 2009.

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular op ...

supports USB 3.0 since version 8.2, which was released in February 2011.

Windows 8 Windows 8 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on August 1, 2012; it was subsequently made available for download via MSDN and TechNet on August 15, 2012, and later to ...

was the first Microsoft operating system to offer built in support for USB 3.0. In

Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was Software release life cycle#Release to manufacturing (RTM), released to manufacturing on July 22, 2009, and became generally available on October 22, ...

support was not included with the initial release of the operating system. However, drivers that enable support for Windows 7 are available through websites of hardware manufacturers.

released its first

chipset In a computer system, a chipset is a set of electronic components in one or more integrated circuits known as a "Data Flow Management System" that manages the data flow between the processor, memory and peripherals. It is usually found on the mo ...

with integrated USB 3.0 ports in 2012 with the release of the

Panther Point The Platform Controller Hub (PCH) is a family of Intel's single-chip chipsets, first introduced in 2009. It is the successor to the Intel Hub Architecture, which used two chips - a northbridge and southbridge, and first appeared in the Intel 5 ...

chipset. Some industry analysts have claimed that Intel was slow to integrate USB 3.0 into the chipset, thus slowing mainstream adoption. These delays may be due to problems in the

CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSF ...

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 PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common mo ...

, SATA 3.0) before developing a new chipset, or a tactic by Intel to favor its new

Thunderbolt A thunderbolt or lightning bolt is a symbolic representation of lightning when accompanied by a loud thunderclap. In Indo-European mythology, the thunderbolt was identified with the 'Sky Father'; this association is also found in later Hell ...

interface. Apple, Inc. announced laptops with USB 3.0 ports on 11 June 2012, nearly four years after USB 3.0 was finalized.

began supporting USB 3.0 with its Fusion Controller Hubs in 2011.

Samsung Electronics Samsung Electronics Co., Ltd. (, sometimes shortened to SEC and stylized as SΛMSUNG) is a South Korean multinational electronics corporation headquartered in Yeongtong-gu, Suwon, South Korea. It is the pinnacle of the Samsung chaebol, a ...

announced support of USB 3.0 with its

ARM In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

-based Exynos 5 Dual platform intended for handheld devices.

Issues

Speed and compatibility

Various early USB 3.0 implementations widely used the

Renesas is a Japanese semiconductor manufacturer headquartered in Tokyo, Japan, initially incorporated in 2002 as Renesas Technology, the consolidated entity of the semiconductor units of Hitachi and Mitsubishi excluding their dynamic random-access mem ...

µD72020x family of host controllers, which are known to require a firmware update to function properly with some devices. A factor affecting the speed of USB storage devices (more evident with USB 3.0 devices, but also noticeable with USB 2.0 ones) is that the

USB Mass Storage Bulk-Only Transfer The USB mass storage device class (also known as USB MSC or UMS) is a set of computing communications protocols, specifically a USB Device Class, defined by the USB Implementers Forum that makes a USB device accessible to a host computing device ...

(BOT) protocol drivers are generally slower than the

USB Attached SCSI USB Attached SCSI (UAS) or USB Attached SCSI Protocol (UASP) is a computer protocol used to move data to and from USB storage devices such as hard drives (HDDs), solid-state drives (SSDs), and thumb drives. UAS depends on the USB protocol, an ...

protocol (UAS drivers. On some old (2009–2010)

Ibex Peak The Platform Controller Hub (PCH) is a family of Intel's single-chip chipsets, first introduced in 2009. It is the successor to the Intel Hub Architecture, which used two chips - a northbridge and southbridge, and first appeared in the Intel 5 ...

-based motherboards, the built-in USB 3.0 chipsets are connected by default via a 2.5

GT/s In computer technology, transfers per second and its more common secondary terms gigatransfers per second (abbreviated as GT/s) and megatransfers per second (MT/s) are informal language that refer to the number of operations transferring data that ...

lane of the PCH, which then did not provide full PCI Express 2.0 speed (5 GT/s), so it did not provide enough bandwidth even for a single USB 3.0 port. Early versions of such boards (e.g. the

P55A-UD4 or P55A-UD6) have a manual switch (in BIOS) that can connect the USB 3.0 chip to the processor (instead of the PCH), which did provide full-speed PCI Express 2.0 connectivity even then, but this meant using fewer PCI Express 2.0 lanes for the graphics card. However, newer boards (e.g. Gigabyte P55A-UD7 or the Asus P7P55D-E Premium) used a channel bonding technique (in the case of those boards provided by a PLX PEX8608 or PEX8613 PCI Express switch) that combines two PCI Express 2.5 GT/s lanes into a single PCI Express 5 GT/s lane (among other features), thus obtaining the necessary bandwidth from the PCH.

Radio frequency interference

USB 3.0 devices and cables may interfere with wireless devices operating in the 2.4 GHz ISM band. This may result in a drop in throughput or complete loss of response with

Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limit ...

and

Wi-Fi Wi-Fi () is a family of wireless network Communication protocol, protocols, based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital d ...

devices. When manufacturers were unable to resolve the interference issues in time, some mobile devices, such as the Vivo Xplay 3S, had to drop support for USB 3.0 just before they shipped. Various strategies can be applied to resolve the problem, ranging from simple solutions such as increasing the distance of USB 3.0 devices from Wi-Fi routers and Bluetooth devices, to applying additional shielding around internal computer components.

Connectors

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 is possible to plug a USB 3.0 Standard-A plug into a USB 2.0 Standard-A receptacle. This is a principle of backward compatibility. The Standard-A is used for connecting to a computer port, at the host side. A USB 3.0 Standard-B receptacle accepts either a USB 3.0 Standard-B plug or a USB 2.0 Standard-B plug. Backward compatibility applies to connecting a USB 2.0 Standard-B plug into a USB 3.0 Standard-B receptacle. However, it is not possible to plug a USB 3.0 Standard-B plug into a USB 2.0 Standard-B receptacle, due to a physically larger connector. The Standard-B is used at the device side. Since USB 2.0 and USB 3.0 ports may coexist on the same machine and they look similar, the USB 3.0 specification recommends that the Standard-A USB 3.0 receptacle have a blue insert (

Pantone Pantone LLC (stylized as PANTONE) is a limited liability company headquartered in Carlstadt, New Jersey. The company is best known for its Pantone Matching System (PMS), a proprietary color space used in a variety of industries, notably graphic ...

300C color). The same color-coding applies to the USB 3.0 Standard-A plug. USB 3.0 also introduced a new Micro-B cable plug, which consists of a standard USB 1.x/2.0 Micro-B cable plug, with an additional 5-pin plug "stacked" inside it. That way, the USB 3.0 Micro-B host connector preserved its backward compatibility with the USB 1.x/2.0 Micro-B cable plugs, allowing devices with USB 3.0 Micro-B ports to run at USB 2.0 speeds on USB 2.0 Micro-B cables. However, it is not possible to plug a USB 3.0 Micro-B plug into a USB 2.0 Micro-B receptacle, due to a physically larger connector.

Pinouts

The connector has the same physical configuration as its predecessor but with five more pins. The VBUS, D−, D+, and GND pins are required for USB 2.0 communication. The additional USB 3.0 pins are two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer; they are used for full duplex SuperSpeed signaling. The GND_DRAIN pin is for drain wire termination and to control EMI and maintain signal integrity.

Backward compatibility

USB 3.0 and USB 2.0 (or earlier) Type-A plugs and receptacles are designed to interoperate. USB 3.0 Type-B receptacles, such as those found on peripheral devices, are larger than in USB 2.0 (or earlier versions), and accept both the larger USB 3.0 Type-B plug and the smaller USB 2.0 (or earlier) Type-B plug. USB 3.0 Type B plugs are larger than USB 2.0 (or earlier) Type-B plugs; therefore, USB 3.0 Type-B plugs cannot be inserted into USB 2.0 (or earlier) Type-B receptacles. Micro USB 3.0 (Micro-B) plug and receptacle are intended primarily for small portable devices such as smartphones, digital cameras and GPS devices. The Micro USB 3.0 receptacle is backward compatible with the Micro USB 2.0 plug. A receptacle for

, which is an eSATA/USB combo, is designed to accept USB Type-A plugs from USB 2.0 (or earlier), so it also accepts USB 3.0 Type-A plugs.

USB 3.1

In January 2013 the USB group announced plans to update USB 3.0 to 10 Gbit/s (1250 MB/s). The group ended up creating a new USB specification, USB 3.1, which was released on 31 July 2013, replacing the USB 3.0 standard. The USB 3.1 specification takes over the existing USB 3.0's ''SuperSpeed USB'' transfer rate, now referred to as ''USB 3.1 Gen 1'', and introduces a faster transfer rate called ''SuperSpeed USB 10 Gbps'', referred to as ''USB 3.1 Gen 2'', putting it on par with a single first-generation

channel. The new mode's logo features a caption stylized as ''SUPERSPEED+''; this refers to the updated ''SuperSpeed Plus'' protocol. The USB 3.1 Gen 2 mode also reduces line encoding overhead to just 3% by changing the

encoding scheme In telecommunication, a line code is a pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium. This repertoire of signals is usually called a constrained co ...

to 128b/132b, with effective data rate of 1,212 MB/s. The first USB 3.1 Gen 2 implementation demonstrated real-world transfer speeds of 7.2 Gbit/s. The USB 3.1 standard is backward compatible with USB 3.0 and USB 2.0. It defines the following transfer modes: * USB 3.1 Gen 1 – SuperSpeed, 5 Gbit/s data signaling rate over 1 lane using 8b/10b encoding (effective 500 MB/s); the same as USB 3.0 * USB 3.1 Gen 2 – SuperSpeed+, new 10 Gbit/s data rate over 1 lane using 128b/132b encoding (effective 1212 MB/s) The nominal data rate in bytes accounts for bit-encoding overhead. The physical SuperSpeed bit rate is 5 Gbit/s. Since transmission of every byte takes 10 bit times, the raw data overhead is 20%, so the byte rate is 500 MB/s, not 625. Similarly, for Gen 2 link the encoding is 128b/132b, so transmission of 16 bytes physically takes 16.5 bytes, or 3% overhead. Therefore, the new byte-rate is 128/132 * 10 Gbit/s = 9.697 Gbit/s = 1212 MB/s. In reality the SuperSpeed+ mode has additional link management and protocol overhead, so the best-case achievable data rates are about 1100 MB/s. This renaming of USB 3.0 as "USB 3.1 Gen 1" has allowed manufacturers to advertise products with transfer rates of only 5 Gbit/s as "USB 3.1," omitting the generation.

USB 3.2

On 25 July 2017, a press release from the USB 3.0 Promoter Group detailed a pending update to the

USB Type-C USB-C (properly known as USB Type-C) is a 24-pin USB connector system with a rotationally symmetrical Electrical connector, connector. The designation C refers only to the connector's physical configuration or form factor and should not be co ...

specification, defining the doubling of bandwidth for existing USB-C cables. Under the USB 3.2 specification, released 22 September 2017, existing SuperSpeed certified USB-C 3.1 Gen 1 cables will be able to operate at 10 Gbit/s (up from 5 Gbit/s), and SuperSpeed+ certified USB-C 3.1 Gen 2 cables will be able to operate at 20 Gbit/s (up from 10 Gbit/s). The increase in bandwidth is a result of multi-lane operation over existing wires that were intended for flip-flop capabilities of the USB-C connector. The USB 3.2 standard is backward compatible with USB 3.1/3.0 and USB 2.0. It defines the following transfer modes: * USB 3.2 Gen 1 – SuperSpeed, 5 gigabit per second (Gbit/s) data signaling rate over 1 lane using 8b/10b encoding (effective 500 MB/s), the same as USB 3.1 Gen 1 and USB 3.0. * USB 3.2 Gen 2 – SuperSpeed+, 10 gigabit per second (Gbit/s) data rate over 1 lane using 128b/132b encoding (effective 1212 MB/s), the same as USB 3.1 Gen 2. * USB 3.2 Gen 1×2 – SuperSpeed+, new 10 gigabit per second (Gbit/s) data rate over 2 lanes using 8b/10b encoding (effective 1000 MB/s). * USB 3.2 Gen 2×2 – SuperSpeed+, new 20 gigabit per second (Gbit/s) data rate over 2 lanes using 128b/132b encoding (effective 2424 MB/s). As with the previous version, the same considerations around encoding and effective data rates apply. Although both Gen 1×2 and Gen 2×1 signal at 10 Gbit/s, Gen 1×2 uses the older, less efficient 8b/10b line coding which results in a lower effective speed, with the newer SuperSpeed+ protocol. In May 2018,

Synopsys Synopsys is an American electronic design automation (EDA) company that focuses on silicon design and verification, silicon intellectual property and software security and quality. Products include tools for logic synthesis and physical design ...

demonstrated the first USB 3.2 Gen 2×2 connection, where a Windows PC was connected to a storage device, reaching an average speed of 1600 MB/s. USB 3.2 is supported with the default Windows 10 USB drivers and in Linux kernels 4.18 and onwards. In February 2019, USB-IF simplified the marketing guidelines by excluding Gen 1×2 mode and required the SuperSpeed trident logos to include maximum transfer speed.USB 3.2 Specification Language Usage Guidelines from USB-IF
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References

External links

* CES 2014 report of a laptop docking port using a single USB 3.1 port to supply power, video and USB peripherals {{Basic computer components #3.0 Computer-related introductions in 2008