Technology

Ask an Expert

Email your product & application enquiries direct to our experts

INTERCONNECT & CABLES

SuperSpeed USB Host Controller applications will use Standard A receptacles on the PCB and plugs, which have extended heads where SuperSpeed USB connectors extend beyond and slightly above the legacy connectors. Similarly, Standard A receptacles are deeper to accept these new connectors. USB 3.0 connectors maintain backward compatibility and accordingly all USB 3.0 receptacles accept the corresponding USB 2.0 plugs. Four connector form factors are defined in the USB 3.0 specifications:

Type-A connectors provide the same interface as the USB 2.0 standard, with added pins for SuperSpeed USB signals. The standard also caters for double-stacked connectors. B-Type connectors are recommended for relatively large, stationary peripherals such as scanners and printers. They are visually different from USB 2.0 Standard – B connectors; however the receptacle does accept a USB 2.0 standard B-type plug.

Powered – B connectors are specified for device-powered applications, for example, wireless adaptors. These are based on the USB 3.0 Standard – B connector design, but have additional device POWER and GND pins. The receptacle accepts standard USB 3.0 and USB 2.0 - B as well as USB 3.0 Powered – B plugs. As with the previous standard, there is a family of micro connectors defined for hand held devices. Based on the USB 2.0 Micro – B connector, Type- A and -AB connectors are identical to the USB 3.0 Micro – B connector except with different keying.

Cable solutions

With higher data rates and EMI concerns, new SuperSpeed USB cables use Shielded Twisted Pair (STP) cables instead of the unshielded cables used for earlier USB standards. One UTP pair carries USB 2.0 signals, one STP pair carries the transmit signals (SSTX+/-), while the other STP pair carries the receive signals (SSRX+/-). Increased data rates do put some constraints on cable assembly lengths; although specifications allow any lengths so long as they meet all other requirements. Cables 3m or shorter will be able to run at SuperSpeed. Several cable assembly options are available for standard products and customized lengths and colors are also available from Amphenol, Samtec and Tyco Electronics.

Useful links: