USB 2.0 has been the ubiquitous external data connection standard for all types of computers since its release in 2000. However with the phenomenal increase in casual users storing large files such as video, audio, and programs, demand for larger capacity hard drives has also increased drastically. The limited maximum transfer rate of USB 2.0 at about 30MB/s (megabytes per second) has become inadequate for the general user. Many computer users are now relying on other types of data interfaces, such as Firewire 800, eSATA / SATA, or Gigabit networks, to transfer large amounts of data between their mass storage devices.

USB 3.0, also known as the SuperSpeed bus, was designed to address the limitation of slow transfer rate. USB 3.0 introduces a fourth transfer mode of 5Gbps (gigabits per second). This new transfer mode upgrades the USB technology to support a maximum throughput of about 600MB/s while still maintaining backwards compatibility with the older signaling rates.

This allows a USB 3.0 mass storage device to be connected onto a legacy USB 2.0/1.1 port, and likewise. It is important to note that there are now two types of connector and plug combinations in USB 3.0 specification, SuperSpeed standard A and SuperSpeed standard B. SuperSpeed standard A plugs will fit legacy A receptacles but SuperSpeed standard B plugs will not fit into legacy standard B receptacles. Below are charts comparing the pinouts of the SuperSpeed standard A plug and the SuperSpeed standard B plug.

The USB 3.0 specification also includes new power management features including support for idle, sleep, and suspend states, as well as Link-, Device-, and Function-level power management. The bus power spec has also been increased to 900mA, an 80% increase over USB 2.0 (500mA).

With the USB 3.0 specification completed and released in 2008, many desktop and notebook motherboard manufacturers such as Gigabyte and Intel either have plans to or have already integrated the latest SuperSpeed USB 3.0 ports into their hardware. It is expected that by the year 2012, over 4 billion USB 3.0 devices will have been shipped.

Transfer rate comparison of USB 2.0 and USB 3.0

Below is a comparison showing the difference in transfer rate between a USB 2.0 port and USB 3.0 port. Taking a look at the sequential Read / Write performance of the SATA drives connected to the USB 2.0 port, we find that even a single 3.5" SATA hard drive will saturate the bandwidth of the USB 2.0 port. On the other hand, there is a significant improvement in performance when comparing a single 3.5" SATA hard drive and a three SATA drive RAID 0 set. In fact, even the three SATA drive RAID 0 set has not yet saturated the USB 3.0 bus.

Addonics USB 3.0 Controllers

Addonics has realized the needs of consumers interested in incorporating the latest USB 3.0 technology into their desktops and notebooks which do not have built in USB 3.0 ports. Below are host controllers and adapters designed to upgrade systems which have either a PCI-Express or ExpressCard slot with two USB 3.0 ports.

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