18-10-2012, 04:00 PM
USB 3.0
USB_3_final.pdf (Size: 1.06 MB / Downloads: 36)
ABSTRACT
In information technology, Universal Serial Bus (USB) is a serial bus standard to connect devices to
a host computer. USB was designed to allow many peripherals to be connected using a single standardized
interface socket and to improve plug and play capabilities by allowing hot swapping; that is, by allowing
devices to be connected and disconnected without rebooting the computer or turning off the device. Other
convenient features include providing power to low-consumption devices, eliminating the need for an
external power supply; and allowing many devices to be used without requiring manufacturer-specific device
drivers to be installed.
The U S B 3.0 is the upcoming version of the Universal Serial Bus (USB). The specification of the
new standard had been announced by USB Implementers Forum (USB-IF). The main feature of the new USB
is the raw throughput is 500 MByte/s. The new USB is also capable to provide more power to drive the
devices. USB 3.0 is highly backward compatible that is, it is capable of operating with the current USBs
which is USB 2.0
UNIVERSAL SERIAL BUS 3.0
INTRODUCTION
Universal Serial Bus (USB) is a serial bus standard to connect devices to a host computer. The USB
3.0 is the upcoming version of the USB. The USB 3.0 is also called super speed USB. Because the USB 3.0
support a raw throughput of 500MByte/s. As its previous versions it also support the plug and play capability,
hot swapping etc. USB was designed to allow many peripherals to be connected using a single standardized
interface socket. . Other convenient features include providing power to low-consumption devices, eliminating the need for an external power supply; and allowing many devices to be used without requiring manufacturer-specific device drivers to be installed.
There are many new features included in the new Universal Serial Bus Specification. The most important one is the supers speed data transfer itself. Then the USB 3.0 can support more devices than the currently using specification which is USB 2.0. The bus power spec has been increased so that a unit load is
150mA (+50% over minimum using USB 2.0). An unconfigured device can still draw only 1 unit load, but a
configured device can draw up to 6 unit loads (900mA, an 80% increase over USB 2.0 at a registered maximum
of 500mA). Minimum device operating voltage is dropped from 4.4V to 4V. When operating in SuperSpeed mode, full-duplex signaling occurs over 2 differential pairs separate from the non-SuperSpeed differential pair. This result in USB 3.0 cables containing 2 wires for power and ground, 2 wires for non-SuperSpeed data, and 4 wires for SuperSpeed data, and a shield (not required in previous specifications).
HISTORY
Prereleases
· USB 0.7: Released in November 1994.
· USB 0.8: Released in December 1994.
· USB 0.9: Released in April 1995.
· USB 0.99: Released in August 1995.
· USB 1.0: Release Candidate: Released in November 1995.
USB 1.0
· USB 1.0: Released in January 1996.
Specified data rates of 1.5 Mbit/s (Low-Speed) and 12 Mbit/s (Full-Speed). Does not allow for extension cables or pass-through monitors (due to timing and power limitations). Few such devices actually made it to market.
· USB 1.1: Released in September 1998.
Fixed problems identified in 1.0, mostly relating to hubs. Earliest revision to be widely adopted.
USB 2.0
USB 2.0: Released in April 2000.
Added higher maximum speed of 480 Mbit/s (now called Hi-Speed). Further modifications to the USB specification have been done via Engineering Change Notices (ECN). The most important of these ECNs are included into the USB 2.0 specification package available from USB.org:
· Mini-B Connector ECN: Released in October 2000.
Specifications for Mini-B plug and receptacle. These should not be confused with Micro-B plug and
receptacle.
· Pull-up/Pull-down Resistors ECN: Released in May 2002.
UNIVERSAL SERIAL BUS 3.0
· Interface Associations ECN: Released in May 2003.
New standard descriptor was added that allows multiple interfaces to be associated with a single
device function.
· Rounded Chamfer ECN: Released in October 2003.
A recommended, compatible change to Mini-B plugs that results in longer lasting connectors.
· Inter-Chip USB Supplement: Released in March 2006.
· On-The-Go Supplement 1.3: Released in December 2006.
USB On-The-Go makes it possible for two USB devices to communicate with each other without requiring a separate USB host. In practice, one of the USB devices acts as a host for the other device.
· Battery Charging Specification 1.0: Released in March 2007.
Adds support for dedicated chargers (power supplies with USB connectors), host chargers (USB hosts
that can act as chargers) and the No Dead Battery provision which allows devices to temporarily draw
100 mA current after they have been attached. If a USB device is connected to dedicated charger,
maximum current drawn by the device may be as high as 1.8A. (Note that this document is not distributed with USB 2.0 specification package.)