USB 2.0, USB 3.0 And USB Type C – USB Ports Explained

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Universal Serial Bus, more commonly known as the USB has been around for quite some time now with almost every device following the standard. From our I/O devices to storage drives and even mobile phones can be connected using the USB standard.

This standard has evolved over the years from its inception in the mid 90’s and has had multiple versions through its history.

So in this article let us have a look at them.

USB 1.x

The initial idea of USB was a collective effort from a group of 7 companies that included Microsoft, Intel, and IBM. They wanted a standard way to connect devices to their systems to increase compatibility and redundant software writing.

With transfer speeds of 1.5 Mbit/s in the first USB 1.0(launched 1996), which later went on to 12 Mbit/s in USB 1.1 revision(launched 1998), the USB specification had gained its grounds.

USB 2.0

Launched in the year 2000 the USB 2.0 specification got a major upgrade and improved its signaling rate to 480 Mbit/s or 60 MByte/s. However, due to bus access constraints, it was limited to 35 MB. Another added feature was the USB OTG which allowed both the connected devices to be hosts or guest depending upon the need.

USB 2.0 created an impression that lasted so long we still see it today as most of USB peripheral devices being made still follow the 2.0 specification.

Talking about the power specifications, USB 2.0 was later implemented with Battery charging specification 1.1 and the current drawn from it was 100 mA for normal devices and up to 1.8A for dedicated chargers.

Later this was revised with version 1.2 to increase the current draw limit to 1.5A and 5A for dedicated chargers.

USB 3.0

USB 3.0 was launched in 2008 and was a big upgrade from 2.0 as the transfer speeds got up to 5 Gbit/s. However, only 3.2 Gbit/s could be achieved whilst no overheating the device.

In my honest opinion, USB 3.0 was the biggest leap in the history of all USB devices ever, mainly because of the transfer speed. Since USB 2.0 had been around for almost 8 years before USB 3.0 got launched in 2008 the market was saturated with USB 2.0 devices. This led to the very slow adoption of USB 3.0.

3.1 & 3.2

In 2013 the USB 3.0 specification was revised to allow transfer speeds up to 10Gbit/s and in 2017 we saw the release of 3.2 allowing speeds up to 20Gbit/s.

USB Type C

Launched roughly around the same period as USB 3.1, USB Type C was a breakthrough in one of the biggest problems with USBs. It had a symmetric design which allowed it to be inserted either ways unlike older designs. The bus featured a newer 24 pin design and its power specifications also allowed for faster charging.

Not only newer mobile phones, but other accessories have also started adopting the USB Type C specification mainly due to its symmetric design.

Summary

The USB specifications have evolved over the years till finally reaching USB Type C. The Frequency of newer specification releases is getting higher. However, Manufacturers are only willing to adopt those specifications which are in demand in the market.

I hope you liked the article, Feel free to use the comment section for any doubts or suggestions.

  • Michael Lippert

    Sorry but I feel your article is perpetuating the confusion people have when they hear about USB C. USB C is not equivalent to the USB 1.0 – 3.2 specifications you talk about but the article makes it seem as though it is.

    USB *type* C is just a new USB cable connector equivalent to (but better than) the previous USB connector types, A, B, mini A and B, micro A and B.

    It is also true that unlike the previous USB connector types, the are more gotchas for USB type C cables, they are *not* all created equal.

  • DaveQB

    So USB type C is just an interface change? It seems like there’s some power transfer improvements too. If it’s just an interface change, then what a PITA needing to carry around little USB type C adapters just to plug your phone in for no benefit; MicroUSB was working fine.

    • Rishabh Kandari

      Hi @DaveQB:disqus , yeah there were indeed power improvements that were running independently of the USB specifications. the current carrying capacity increased with the charging specification versions.

      • DaveQB

        But we didn’t need the change in connector for this power improvement?

        Thanks

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