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USB 3.0 – Specs

I was just looking into the stats of USB 2.0 for a printer problem, when I just happened to see some stats for the USB 3.0 standard. I thought that it would be nice to compare the two briefly and to find out why I should buy USB 3.0 devices instead of USB 2.0.


USB 2.0

USB 3.0


480Mbps (320Mbps in real world)

Up to 4.8Gbps


Half-duplex (polling)

Full-duplex (asynchronous)

Cable Length

3 meters (low speed) 5 meters (high speed)

3 meters (maybe longer when optic cables can be used in a future spec revision)


Most of the changes are in the connector of course. The connector now has 8 wires (power, ground, 1 pair for differential data, and 2 pairs for differential signals). The last 2 pairs were needed for the SuperSpeed USB target bandwidth requirements, as the dual wire differential signals of USB 2.0 weren’t enough.

The power output has been upped by 50% for unconfigured or suspended devices (150 mA up from 100 mA). For configured devices the power output has been upped by 80% (900 mA up from 500 mA). Which might mean that you’re gonna be able to lose some of those big nasty power adapters and battery powered devices that are charged by USB power (iPhone for example) can be charged more quickly. Like all other devices USB 3.0 is going green with improved power efficiency.

If you want to know more about USB 3.0 you might want to visit this link. Most of the data above has been compiled from this page and some others. They also have some data on how USB 3.0 compares to other competing interfaces.

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Posted by Mischa Oudhof

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