USB has a rogues gallery of connectors and matching cables that has grown from a simple pair of connectors to a plethora of combinations designed to address a range of applications and hardware environments. High-retention USB connectors, which allow the interface to be used in more rugged, embedded environments, are found on boards such as AccesIO’s USB-AO 16 series (see “USB Modules Target DAQ Apps”).
Also, USB is delivered via 10-pin motherboard headers. It’s incorporated into other standard interface connections such as StackableUSB that use a Samtec connector (see “Micro/sys Dishes Out Stackable USB For Embedded I/O”) like that found on the Micro/sys i.MX515-based SBC1651 (Fig. 1) as well .
The USB A connector (Fig. 2) is ubiquitous. It is found on PCs and laptops. It’s also used on flash memory drives. It provides a connection to a hub. The USB Micro-A connector (Fig. 3) is designed for more compact hosts.
The A connectors are found at one end of a USB cable. At the other end will be a B connector. The USB B connector (Fig. 4) is the largest of the group. Sockets are normally found on devices like printers and scanners. The USB Mini B (Fig. 5) and USB Micro B (Fig. 6) connectors are used with a variety of compact devices.
The USB SuperSpeed connectors look very similar to the standard USB connectors but with a minor addition. This approach adds support for the high-speed differential pairs while allowing connectors and plugs to work in a backward-compatible fashion.
The USB SuperSpeed Standard A connector (Fig. 7) looks like the Standard A connector. Hidden on the opposite side of the regular connections, though, are the new differential pairs. The socket can accept a Standard B plug.
At the other end of a SuperSpeed cable will be a USB SuperSpeed Standard B (Fig. 8) or USB SuperSpeed Micro-B (Fig. 9) connector. The USB SuperSpeed Standard B places the high-speed pairs above while the Micro-B puts them on one side.
Other standards support USB connections such as ExpressCard (Fig. 10), which is found on laptops, and SFF-SIG’s MiniBlade (Fig. 11). These standards use specific plugs and sockets, whereas the standard USB plugs are found at either end of a cable. ExpressCard 2.0 specifies support for the latest PCI Express and USB 3.0 standards.