USB 3.0

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 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, (electrically, it is more similar to PCI Express 2.0 and SATA 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 , or , about ten times as fast as USB 2.0 () even without considering that USB 3.0 is full duplex whereas USB 2.0 is half duplex. This gives USB 3.0 a potential total bidirectional bandwidth twenty times as great as that of USB 2.0. Considering flow control, packet framing and protocol overhead, applications can expect of bandwidth. Data encoding The "SuperSpeed" bus provides for a transfer mode at a nominal rate of , in addition to the three existing transfer modes. Accounting for the encoding overhead, the raw data throughput is , and the specification considers it reasonable to achieve () 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; this helps prevent transmissions from generating electromagnetic interference (EMI). 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. Naming scheme Starting with the USB 3.2 specification, USB-IF introduced a new naming scheme. To help companies with branding of the different operation modes, USB-IF recommended branding the 5, 10, and capabilities as SuperSpeed USB 5Gbps, SuperSpeed USB 10 Gbps, and SuperSpeed USB 20 Gbps, respectively.In 2023, they were replaced again, replacing "SuperSpeed" with USB 5Gbps, USB 10Gbps, and USB 20Gbps, and introducing new Packaging and Port logos. ==Availability==

chipset 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-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 on 5 January 2010, at the Las Vegas Consumer Electronics Show (CES), including two motherboards by Asus and Gigabyte Technology. Manufacturers of USB 3.0 host controllers include, but are not limited to, Renesas Electronics, Fresco Logic, ASMedia, Etron, VIA Technologies, Texas Instruments, NEC and Nvidia. As of November 2010, Renesas and Fresco Logic have passed USB-IF certification. Motherboards for Intel's Sandy Bridge processors have been seen with Asmedia and Etron host controllers as well. On 28 October 2010, Hewlett-Packard released the HP Envy 17 3D featuring a Renesas USB 3.0 host controller several months before some of their competitors. AMD worked with Renesas to add its USB 3.0 implementation into its chipsets for its 2011 platforms. At CES2011, Toshiba unveiled a laptop called "Qosmio X500" that included USB 3.0 and Bluetooth 3.0, and Sony released a new series of Sony VAIO laptops that would include USB 3.0. As of April 2011, the Inspiron and Dell XPS series were available with USB 3.0 ports, and, as of May 2012, the Dell Latitude laptop series were as well; yet the USB root hosts failed to work at SuperSpeed under Windows 8. Adding to existing equipment , DisplayPort connector, USB 2.0 Standard‑A (host) port. On the motherboards of desktop PCs which have PCI Express (PCIe) slots (or the older PCI standard), USB 3.0 support can be added as a PCI Express expansion card. 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 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, 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. Adoption The USB Promoter Group announced the release of USB 3.0 in November 2008. On 5 January 2010, the USB-IF 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 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 contains support for USB 3.0 since version 2.6.31, which was released in September 2009. FreeBSD supports USB 3.0 since version 8.2, which was released in February 2011. Windows 8 was the first Microsoft operating system to offer built in support for USB 3.0. In Windows 7 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. Intel released its first chipset with integrated USB 3.0 ports in 2012 with the release of the Panther Point 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 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 favor its new Thunderbolt interface. Apple, Inc. announced laptops with USB 3.0 ports on 11 June 2012, nearly four years after USB 3.0 was finalized. AMD began supporting USB 3.0 with its Fusion Controller Hubs in 2011. Samsung Electronics announced support of USB 3.0 with its ARM-based Exynos 5 Dual platform intended for handheld devices. ==Issues==

Speed and compatibility Various early USB 3.0 implementations widely used the NEC/Renesas 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 (BOT) protocol drivers are generally slower than the USB Attached SCSI protocol (UAS[P]) drivers. On some old (2009–2010) Ibex Peak-based motherboards, the built-in USB 3.0 chipsets are connected by default via a PCI Express lane of the PCH, which then did not provide full PCI Express 2.0 speed (), so it did not provide enough bandwidth even for a single USB 3.0 port. Early versions of such boards (e.g. the Gigabyte Technology 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 lanes into a single PCI Express 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 and Wi-Fi devices. When manufacturers were unable to resolve the interference issues in that 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 mitigate the problem, ranging from simple solutions, such as increasing the distance of USB 3.0 devices from Wi-Fi and Bluetooth devices, to applying shielding and grounding around USB devices and USB hosts. ==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 plug 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 the physically larger connector. The Standard‑B plug 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 300 C 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" beside it. That way, the USB 3.0 Micro‑B host receptacle preserves its backward compatibility with the USB 1.x/2.0 Micro‑B cable plug, 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 the physically larger connector. Pin assignments 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 five 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 eSATAp, 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==

overhead to just 3% by changing the scheme to 128b/132b, with raw data rate of . The first USB 3.1 Gen 2 implementation demonstrated real-world transfer speeds of . The USB 3.1 specification includes the USB 2.0 specification while fully preserving its dedicated physical layer, architecture, and protocol in parallel. USB 3.1 specification defines the following operation modes: • USB 3.1 Gen 1 – newly marketed as SuperSpeed or SS, signaling rate over 1 lane using 8b/10b encoding (raw data rate: ); replaced USB 3.0. • USB 3.1 Gen 2 – new, marketed as SuperSpeed+ or SS+, signaling rate over 1 lane using 128b/132b encoding (raw data rate: ). The nominal data rate in bytes accounts for bit-encoding overhead. The physical SuperSpeed signaling bit rate is . Since transmission of every byte takes 10 bit times, the raw data overhead is 20%, so the raw 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 raw byte-rate is 128/132 * = = . In reality, any operation mode has additional link management and protocol overhead, so the best-case achievable data rates for the Gen 2 operation mode are of roughly below for reading bulk transfers only. ==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 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 (up from ), and SuperSpeed+ certified USB‑C 3.1 Gen 2 cables will be able to operate at (up from ). 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 includes the USB 2.0 specification with four dedicated wires on the physical layer. The Enhanced SuperSpeed System encompasses both, but separated – and in parallel to the USB 2.0 implementation: which is 66% of its raw throughput. 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. ==See also==