PC Components & Tech

Defining USB, Types & How Do They Work?









USB or Universal Serial Bus was introduced in 1994 by Intel Corp although the official version 1.0 wasn't released until 1996.  Due to it's early limitations (mostly timing problem and lack of HUBs), it wasn't until version 1.1 was released in August of 1998 that USB began to gain acceptance.  It is now the De-Facto Standard for PC connectivity.   Mouse, printer, digital camera, webcam, speaker, modem, network connection…etc can now be interfaced to the PC with relative ease (plug and Play).  Offering speed mobilty and flexibility to you peripheral devices. USB can offer low power to these devices of 5 volts DC (See Chart Below).   In the early days of USB only 150MA or .75 watts of power was supplied if you drew too much power your computers' power supply would shut down due to an over-currnet condition, thus requiring you to power down you computer and power it back on again.  If this occured too often you power supply over-current protection circuits would become week eventually require replacing.  For that reason USB devices requiring  high power came with it's own power supply (either internal or external).


USB can connect up to 127 devices through the use of HUBs (Hollow Ugly Boxes...LOL). although power is not passed through the hub. If the hub is powered, it can provide power to any devices connected to it.



USB Power Standards.
USB 1.0        5 Volts        150mA         .75 Watts

USB2.0         5 Volts        500mA         2.5 Watts
USB 3.0        5 Volts        900 mA        4.5 Watts
USB 3.1        5 Volts        2  A             10 Watts
                    12 Volts       5 A              60 Wa tts
                    20 Volts       5 A              100 Watts


USB 1.1 had a speed of 1.5 Megabits (Mbit/s) per second "Low Speed" with a maximum of 12 Megabits (Mbit/s) per second "Full Speed" . The connector is typically white.

USB 2.0 was released in April of 2000 and was called "High Speed"  with a theoretical data transfer rate of 480 Mbit/s (Notice my use of the term Theoretical, typical data rates of 35MegaBytes per Second or 280Mbit/s). The connector is typically black but sometimes white.

USB 3.0 was released in November of 2008 and was called "SuperSpeed" with a theoretical data rate transfer rate of 5 Gbits/s and an typical data  rate of 3.2Gbit/s.  Also added was a Battery Charging specification requiring the connector be able to handle 5 Amps  although the Specification limits the power to 1.5 Amps,  In this mode, however  data transfer is not possible, because data+ and data- are shorted together as per the specification.  USB 3.0 is backward compatible to USB 2.0. The connector is typically blue.

USB 3.1 was releaded on July 31, 2013  and was called "SuperSpeed+" with a theoretical data rate transfer rate of  10 Gbit/s (double that of USB 3.0) and an typical data rate of 7.2Gbit/s. USB 3.1 is backward compatbile with USB 3.0 and USB 2.0.  It consists of two simultaneously active buses: a USB 2.0 bus and an Enhanced SuperSpeed bus.  The cabling allows for additional twisted pair wires for SuperSpeed Tx+,Tx-  and Rx+,Rx- lines.  USB 3.1 cables are NOT intended to be compatible with USB 2.0.  A new chipset is in the works.  The additional speed will assist in 4k Video over USB. Also a major change being, the supply of additional power of 12 volts and 20 volts and higher current handling rates. (See Chart Above)


Sleep-and-charge USB ports can be used to charge electronic devices even when the computer is switched off. Normally, when a computer is powered off, the USB ports are powered down. These ports are found colored differently (mostly red and yellow).


ThunderBolt was developed by Intel in 2009 called Light Peak.  This was not a USB specification but an entirely different Specification for Plastic Fiber Optical Interface.  But its confusion with USB is why I mention it here.  Delivering a speed of 10 Gbit/s. with a goal of 100Gbit/s. It would primarily be using DisplayPort protocols used to deliver 4k Video streams from Graphics cards and Network Interfaces.  The spec was modified to add Copper wire so power could be provided from USB 3.0 or USB 4.0 devices. While it is not clear if Thunderbolt will be added to the USB spec. The ultimate goal will be the 100 Gbit/s bandwidth.  Apple has already implemented the Thunderbolt DisplayPort to  its'  2011 MacBook Pro. With the US  company, Coming Inc.,  beginning to sell 100 Meter (330 ft) optical USB 3.0 and ThunderBolt cables in September 2013. For more information go to http://thunderbolttechnology.net


The Chart Belows Shows the USB Pinouts and USB voltages of the connector:

























The charts below show Connectors and Cables with pairs of plugs:

















































 Data throughout can be shown in the chart below.  Again your milage may vary.




















In the future, USB 4.0 is slated to reach the market by 2016.  It will have a connector that is invertable, that is it can be plugged in upside down.  This is called a Type-C connectorand was added to the USB 3.1 Specification. That means the old USB connector will need an adapter, if it will work at all. (remember keyboard and mouse connector changes in the 80's -90's and 9 pin serial and 27 pin serial adapters). Of course, this is a few years from now.  With the speed ThunderBolt,100 Gbits/s.  No Specification is out as of this writing.  So no pictures of USB 4.0 yet. We will keep checking for updates.




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