USB 1.0, USB 2.0 and USB 3.0


Xmultiple's Engineering Department

USB supports the following signaling rates: The terms speed and bandwidth are used interchangeably. "high-" is alternatively written as "hi-".

USB 1.0

The original USB 1.0 specification, which was introduced in January 1996, defined data transfer rates of 1.5 Mbit/s "Low Speed" and 12 Mbit/s "Full Speed".[5] The first widely used version of USB was 1.1, which was released in September 1998. The 12 Mbit/s data rate was intended for higher-speed devices such as disk drives, and the lower 1.5 Mbit/s rate for low data rate devices such as joysticks. A low-speed rate of 1.5 Mbit/s (~183 kB/s) is defined by USB 1.0. It is very similar to full-bandwidth operation except each bit takes 8 times as long to transmit. It is intended primarily to save cost in low-bandwidth human interface devices (HID) such as keyboards, mice, and joysticks.
The full-speed rate of 12 Mbit/s (~1.43 MB/s) is the basic USB data rate defined by USB 1.1. All USB hubs support full-bandwidth.

USB 2.0

The USB 2.0 specification was released in April 2000 and was standardized by the USB Implementers Forum (USB-IF) at the end of 2001. Hewlett-Packard, Intel, Lucent Technologies (now Alcatel-Lucent), NEC and Philips jointly led the initiative to develop a higher data transfer rate, with the resulting specification achieving 480 Mbit/s, a fortyfold increase over the original USB 1.1 specification. A high-speed (USB 2.0) rate of 480 Mbit/s (~57 MB/s) was introduced in 2001. All hi-speed devices are capable of falling back to full-bandwidth operation if necessary; i.e. they are backward compatible with USB 1.1. Connectors are identical for USB 2.0 and USB 1.x.The theoretical maximum data rate in USB 2.0 is 480 Mbit/s (60 MB/s) per controller and is shared amongst all attached devices. Some chipset manufacturers overcome this bottleneck by providing multiple USB 2.0 controllers

USB 3.0

he USB 3.0 specification was published on 12 November 2008. Its main goals were to increase the data transfer rate (up to 5Gbps), to decrease power consumption, to increase power output, and to be backwards-compatible with USB 2.0.[7] USB 3.0 includes a new, higher speed bus called SuperSpeed in parallel with the USB 2.0 bus.[8] For this reason, the new version is also called SuperSpeed.[9] The first USB 3.0 equipped devices were presented in January 2010. A SuperSpeed (USB 3.0) rate of 4800 Mbit/s (~572 MB/s). The written USB 3.0 specification was released by Intel and partners in August 2008. The first USB 3 controller chips were sampled by NEC May 2009[55] and products using the 3.0 specification arrived beginning in January 2010.[56] USB 3.0 connectors are generally backwards compatible, but include new wiring and full duplex operation.

USB 3 pinout

Pin Color Singnal name ('A' connector Singnal 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-


Shell Shell Shield  


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