Properties of a USB Connector
Author：danny / time：2018-04-10 / The number of clicks：789
The USB connector is a standard data connection and transfer interface developed in the mid-1990s to replace old serial and parallel ports. Today, three decades later, it remains to be one of the most popular data connection systems, owing to its ease of use, flexibility, compatibility, and power capabilities.
There are two basic parts of a USB connector:
Receptacle. A USB receptacle is the “female” connector mounted on the host, such as a computer, or a device, such as a digital camera or a printer.
Plug. A USB plug is the “male” connector attached to the cable.
Unlike other older connectors, the USB is held in place to the peripheral device and the cord by the gripping force from the receptacle. There are no thumb-turns, screws, or clips required to keep it in place.
Featuring improved design, the USB is designed to be stronger and more durable than previous connectors. This is because it is hot-pluggable, a property that allows a USB connector to be added to a running computer system without significantly interrupting the operation (i.e., shutting down or restarting the computer).
To expand the lifespan of a standard USB, modifications to its design were implemented. From the jack, the leaf spring was moved to the plug. A locking device was likewise added to keep the connector secure in its place.
Insertions and removals
With these improvements, a standard USB can now withstand up to 1,500 repetitions of insertions and removals. The mini-B connectors, on the other hand can last up to 5,000 cycles of insertions and removals after further improvements.
The micro-connectors prove to be the most durable. They are designed to withstand up to 10,000 repetitions of insertions and removals. To achieve this, flexible contacts were put in place on the easily replaceable cable. The receptacles, on the other hand, are the ones that house the more durable rigid contacts.
A close look at the USB would reveal an adjacent plastic tongue. This is complemented by an enclosing metal sheet that protects the whole length of the connecting assembly. These give added protection to the USB .
In addition to these, the plug features a shell, which makes first contact with the receptacle before the pins connect to the host. To shield the wires from within the connector, this shell is grounded, which also helps dissipate static electricity.
Despite these positive features and enhancements in the USB, there are still limitations to the capabilities of this data transfer interface.
First of all, USB cables cannot connect peripheral devices and computers that are more than five meters (or 16 feet and five inches). Because is designed to link devices on a single tabletop, and not between structures or rooms, the USB connector is limited in length.
This, however, can be addressed by using self-powered USB hubs or active (repeater) cables. Extending the length of a USB cable can also be achieved by using USB over Ethernet or building a USB bridge.
USB hub. If you’re using a 2.0 hub and cable, keep in mind that the distance between each powered hub can be no longer than the maximum length of the USB cable, which is five meters (or 16 feet and five inches).
If you’re using a 3.0 or 3.1 hub and cable, on the other hand, the longest distance it can go is shorter at three meters (or nine feet and 10 inches).
Active (repeater) cable. For 2.0 devices, make sure that the regular cable is not more than five meters (or 16 feet and five inches) long. For 3.0 devices, the regular cable should not be longer than three meters (or nine feet and 10 inches).
Despite these limitations, the USB connector is still the most functional data transfer interface today. Upgrades to this connector are expected to focus on increased transfer rates, enhanced compatibility, and improved durability.