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USB 3.0 Vs USB 2.0 – differences and comparison

January 21st, 2011 Leave a comment Go to comments


The USB 3.0 has finally started appearing, at least in some of the high end notebooks today. It is worthwhile to take a look at the USB 3.0 Vs USB 2.0 and its evolution.

USB 3.0 Vs USB 2.0 Key points

– USB 3.0 is backwards compatible with USB 2.0. You will be able to hook any existing USB 2.0 device to USB 3.0 host.

– USB 3.0 Vs USB 2.0 Speed – theorically USB 3.0 has 5 giga bits per second speed, almost 10 times the speed of the present USB 2.0 at 480 mega bits per second.

– The USB 3.0 devices can draw more power than the USB 2.0. In the USB 2.0 the maximum current was limited to 500 mA. Any devices that needed more than 500 mA, had to source its supply from an external power supply source. In USB 3.0, this limit has been raised to 900 mA.

– While USB 2.0 has half duplex data transfer, USB 3.0 supports full duplex data transfer rate.

– The USB 3.0 needs new cable with newer specifications to support higher data rates.


– USB 3.0 Vs USB 2.0 Connectors – Even though the connector for the USB 3.0 is backward compatible with USB 2.0, it is different, has additional pics to support bidirectional data transfer. The five additional connections that come with USB 3.0 connector will take contact only when USB 3.0 device is connected.

– Better idle power management by elimination of polling.

– Cable Length USB3.0 Vs USB2.0 – Well not all is good with the USB 3.0. The high data rate menas that the maximum length of cable that can be run on the USB 3.0 will be less than that of the 2.0. The USB 3.0 will typically have a length limitation of about 3.0 meter.

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  1. October 31st, 2011 at 16:59 | #1

    Interesting article about usb cables, but i think soon transfer speed of the cables will be too slow again

  2. pt456
    November 22nd, 2012 at 18:39 | #2

    In Real world the difference will not be as dramatic as it sounds. In transferring large files the USB 3.0 Vs USB 2.0 makes a difference of someting like 1:2 to 1:4 depending upon the size of the file. This is much below the 1:10 hype.