USB 3.0
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SuperSpeed USB logo
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| Type | USB | ||
|---|---|---|---|
| Designed | November 2008 | ||
| Manufacturer | USB 3.0 Promoter Group (Hewlett-Packard, Intel, Microsoft, NEC, ST-Ericsson, and Texas Instruments) | ||
| Superseded | USB 2.0 Hi-Speed | ||
| Superseded by | USB 3.1 (July 2013) | ||
| Width | 12 mm (A plug), 8 mm (B plug), 12.2 mm (Micro-A & Micro-B plugs) | ||
| Height | 4.5 mm (A plug), 10.44 mm (B plug), 1.8 mm (Micro-A & Micro-B plugs) | ||
| Pins | 9 | ||
| Max. current | 900 mA | ||
| Data signal | Yes | ||
| Bitrate | 5 Gbit/s (625 MB/s) | ||
USB 3.0 is the third major version of the Universal Serial Bus (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 (625 MB/s), which is about ten times as fast as the USB 2.0 standard. Manufacturers are recommended to distinguish USB 3.0 connectors from their USB 2.0 counterparts by blue color-coding of 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 USB transfer rate, now called USB 3.1 Gen 1, while defining a new transfer rate called SuperSpeed USB 10 Gbps, also called USB 3.1 Gen 2, which can transfer data at up to 10 Gbit/s (1.25 GB/s, twice the rate of USB 3.0), bringing its theoretical maximum speed on par with the first version of the Thunderbolt interface.
The specification of USB 3.0 is similar to that of 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:
USB 3.0 has transmission speeds of up to 5 Gbit/s, which is about ten times faster than USB 2.0 (480 Mbit/s) even before taking into account the fact that USB 3.0 is full duplex whereas USB 2.0 is half duplex. This gives USB 3.0 a potential total bandwidth, if used both ways, of twenty times that of USB 2.0.
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. Connections are such that they also permit forward compatibility, that is, running USB 3.0 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.
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