Feature: Connectors
The life and times of the RJ45 connector
By Tom Hennessey, Business Manager, GTK
T
he RJ45 connector has been around for decades, supporting networking technology that did not exist when it was originally designed. In effect, it became the de-facto connector for network cabling in the 1990s, superseding coax cabling. In the ensuing thirty years, Ethernet cabling
made exponential advances; so, how is it that the RJ45 connector is able to stand the test of time and continue supporting today’s technology? The RJ45 connector is part of the Registered Jack connector family, hence the “RJ”. The registered jack interface system was
44 December/January 2023
www.electronicsworld.co.uk
The ingenuity of the original RJ45 connector design made it extremely popular and practical, and influenced the decision to continue using it for copper Ethernet networks
introduced by the Bell System in the 1970s, and adopted by the Federal Communications Commission (FCC) to denote the physical characteristics of a range of modular connectors and assign electrical signals to their contacts. Other members of the RJ family include the RJ11, RJ12, RJ14 and RJ25 connectors; there are numerous others. The “RJ45” label denotes an eight position, eight contact connector, where the contacts in both the plug and jack are evenly spaced. Typically, the RJ45 jack (female connector) is used for fixed
locations such as walls, panels or equipment, whereas the plug (male) is used on cables and patch cords.
RJ45 attributes The size and modularity of the RJ45 jack is one of its greatest attributes. It is small when compared to its I/O connector predecessors, and its uniform shape means it is easy to position multiple jacks together on a PCB. This linear shape also makes possible to have different PCB mounting options, such as top- or side-entry versions, and even offer shielded versions. Other attributes of the connector that have made it so popular include:
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