USB 3.0 Features and Differences from USB 2

By Dipankar Das, Gaea News Network
Friday, January 15, 2010

usb  Overview of USB 3.0:

The new superspeed USB 3.0 is the next generation of universal serial bus that enhances the communication between host computers and the peripheral devices. USB 3.0 is going to co-exist with USB 2.0.  USB 2.0 and USB 1.1 devices are compatible with USB 3.0 ports and connectors. However, they will not achieve USB 3.0 speeds or take advantage of USB 3.0 features. Windows 7 and Linux 2.6.31 plan to support USB 3.0 natively. All other operating systems are going to have drivers or updates in the future to support it.

The essential features of USB 3.0 are:

  • Higher transfer rate (upto 4.8 GBS)
  • Increased maximum bus power and increased device current draw to satisfy the need of those devices that require more power.
  • Better power management feature to reduce active and idle power requirements.
  • Full-duplex data transfers and support for new transfer types.
  • New backward compatible cable and connectors to support higher data transfer.

Difference between USB 2.0 and 3.0:

  • USB 2.0 has 4 wires: two data lines, power and ground. USB 3.0 uses an extra 5 wires – two transmit lines, two receive lines and an additional ground – for a total 9. The extra wires makes an additional bus that works in parallel with the HighSpeed USB 2.0 port.
  • USB 3.0 is asynchronous. The controller will send packets ‘asynchronously’ point-to-point directly to the right device instead of broadcasting packet to every USB device. This is done by using information contained in the data packet’s header. Hence, there is no need for polling.
  • Power efficiency is the main objective for USB 3.0. More power is required when needed. 50% more power is provided for unconfigured device and 80% more power is provided by configured device.
    Less power is required when not needed. For example, Link level power management, which means either the host computer or the device can initiate a power savings state when idle.
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