The USB Roadmap

The older version USB 2.0 communications are all half-duplex and directionally controlled by the host. The new and improved USB 3.0 is a full-duplex (two data transfer channels, instead of one) styled communications, utilizing SuperSpeed data transfer capabilities. USB 3.0 receptacles are electrically compatible with the 2.0 device plugs in most combinations.

Questions you might be asking yourself:

1. What are the different series of connectors?
2. What standard connector combinations does the USB come in?
3. Which is better, 3.0 or 2.0?

Connector Series

The standard USB cables can be fitted with three different series of connectors, Standard A and B, Mini A and B, and Micro AB and B. Each series of connectors is an evolution from the previous series. Both 2.0 and 3.0 versions share the same connector series.

Standard Connectors

• Type A- Inserts into a "downstream-port" to the USB host and carries both power and data. This plug is frequently seen on cables that are permanently attached to a device, such as those with a keyboard or computer mouse. This is because the USB connections eventually wear out as the male and female connectors loosen through repeated plugging and unplugging. The lifetime for a Type A male connector is approximately 1,500 connect/disconnect cycles.
• Type B- Typically is an "upstream receptacle" on a device that uses a removable cable such as a printer. In addition to supplying data, the Type B connector also supplies power. On some devices, the Type B has no data connection, it’s solely for power.

Mini Connectors

·         Mini-A and Mini-B: Thinner versions of their big brothers Type A and Type B. Mini A and B are often used by digital camcorders, but have the same capabilities as the standard connectors.

Micro Connectors

·         Micro-A and Micro-B: The thinner and even smaller Micro series are intended to replace the Mini connectors in new devices including smartphones and personal digital assistants (PDAs). Unlike the Standard and Mini connectors the Micro connectors are design rated for at least 10,000 connect-disconnect cycles. As a result, the Micro connectors have a longer life cycle.

USB Standard Connector Combination Chart
Plug	Micro B	Micro A	Mini-B	Standard B	Standard A
Standard A	Yes	NS	YES	YES	NS
Standard B	No	NS	No	No
Mini-B	No	NS	No
Micro B	Yes	No
Micro B	No

*NS= Not Standard

3.0 vs. 2.0

In a side by side comparison of the 3.0 vs. the 2.0, seems to be far superior to its older brother 2.0. A new feature is the "SuperSpeed" bus, which provides a fourth transfer mode at 5.0 Gbit/s. The raw throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (0.4 Gbyte/s or 400 MByte/s), or more, after protocol overhead. When operating in SuperSpeed mode full-duplex signaling occurs over two differential pairs separate from the non-SuperSpeed differential pair. This results in USB 3.0 cables containing two wires for power and ground, two wires for non-SuperSpeed data, and four wires for SuperSpeed data, and a shield that was not required in previous specifications. If you want speed, compatibility, and reliability, USB 3.0 is the newest USB on the market.

For addition USB 3.0 Specifications, click here to down JEM's USB White Papers!