Detailed introduction of RJ45 connector products

What is the RJ45 connector?

RJ45 is a connector of information socket (communication lead) in wiring system. The connector consists of plug (connector, crystal head) and socket (module). The plug has 8 grooves and 8 contacts. RJ stands for Registered Jack, meaning "Registered socket". In the FCC (federal communications commission standards and regulations), RJ is the interface that describes public telecommunications networks, and RJ45 for computer networks is the common name for the standard 8-bit modular interface.

What are the functions of the RJ45 plug/crystal head?

RJ45, also known as RJ45 crystal Plug, is designed for Modular connection and change of devices and distribution racks. RJ45 crystal head is required to have good conducting performance; The gold-plated thickness of the trigemine reed at the contact point is 50 microns, which meets the transmission standard of super 5 and conforms to the line sequence of T568A and T568B. It has the functions of preventing loosening, inserting and pulling, self-locking and so on.

The RJ45 plug is the standard connector in the copper wiring, which together with the socket (RJ45 module) forms a complete connector unit. The connectors of the two components are connected between the wires to achieve electrical continuity of the wires. It is also an integral part of the integrated wiring technology finished jumper, the RJ45 crystal head is normally connected to both ends of the pair of twisted cables. In the specification of integrated wiring design and installation, this accessory product is usually not listed separately, that is, the user is not recommended to complete the connection work between twisted pair and RJ45 plug.

RJ45 plugs are classified into non-shielded and shielded types. The shielding RJ45 plug is covered by a shielding envelope, and its physical appearance is no different from that of non-shielding plugs. There is also a shielded RJ45 plug specially designed for industrial use in factory environments and used in conjunction with shielded modules.

RJ45 plugs usually use a non-slip plug sheath, which is used to protect the plug connection, anti-slip and easy to plug and unplug. In addition, it has a variety of color options, which can provide the same color as the embedded icon for correct connection.

RJ45 socket/module specification

The commonly used RJ45 non-shielded modules are 2cm high, 2cm wide and 3cm thick, resistant to high pressure and flame retardant, and can be attached to any m-series patterned panel, bracket or surface installation box, and can be installed on standard panel at 90° (vertical) or 45° bevel Angle. Special process design provides at least 750 times of repeated insertion and removal. The module USES t568-a and t568-b wiring universal labels. This kind of module is the most widely used module in the integrated cabling system. No matter from three categories, five categories, super five categories and six categories, its appearance has maintained a fairly consistent.

RJ45 socket/module classification

The wiring structure and appearance of information modules from different manufacturers are not consistent, and the classification methods are also different.

1. According to the installation position of RJ45 module, it is divided into four standards: embedded type, carpet type, table type and universal type.

2. Classified into non-shielded modules and shielded modules according to shielding performance. When installing a shielded cable system, the entire link must be shielded, including cables and connectors, using shielded information modules.

3. The information module can be divided according to whether the module needs wiring or not at the end. There are wiring type and no-wiring type information modules. The wiring mode information module needs special wiring tools to press the twisted-pair wire into the wiring slot of the information module. The wire-free tool design is also a reflection of the humanized design of the module, which does not require the use of special cutting tools.

4. According to different wiring parts, it can be divided into two types: upper end connection and tail end connection. Most products adopt upper end connection.

Design principle of RJ45 connector

The RJ45 consists of a plug and socket, which are connected to the connector between the wires to achieve electrical continuity of the wires.

The core of RJ45 module is modular jack. Gold-plated leads or socket holes maintain a stable and reliable electrical connection to the modular socket shards. Due to the friction between the shrapnel and the socket, the electrical contact is further strengthened with the insertion of the plug. The body of the jack is designed with an integral locking mechanism, so that when the modular plug is inserted, the maximum drawing strength can be generated outside the interface between the plug and the jack. The wiring module on the RJ45 module is connected to the twisted pair through the "U" shaped wiring slot. The locking shrapnel can fix the RJ45 module on the panel and other information outlet devices.

RJ45 connector wire sequence connection sequence

There are T568A or T568B structures between the information module or RJ45 plug and twisted pair end. In T568A, the eight lines connected with it are defined as white green and green respectively; White orange, blue; White and blue and orange; White brown, brown. In T568B, the eight lines connected with it are defined as: white orange, orange; White, green and blue; White, blue, and green; White brown, brown. The differential transmission lines defined are white orange and orange cables, white green and green cables, white blue and blue cables, white brown and brown cables.

In order to achieve the best compatibility, T568B standard is generally adopted when making straight wires. The serial number of the RJ45 crystal pin should be observed as follows: place the RJ45 plug face (the side with the copper pin) towards yourself, with one end of the copper pin facing up and one end of the connecting cable facing down, and number the 8 copper pins from left to right as 1 ~ 8.

The corresponding line sequence from pin 1 to pin 8 is:

T568A: (1) white-green, (2) green, (3) white-orange, (4) blue, (5) white-blue, (6) orange, (7) brown

Formula 1: green, blue, orange and brown, light color in front, three five interchange

Formula 2: white green green, white orange blue, white blue orange, white brown brown

T568B: white-orange, orange, white-green, (4) blue, (5) white-blue, (6) green, (7) brown

Formula 1: orange blue green brown, light color in front, three five interchange

Formula 2: white orange, white green blue, white blue green, white brown brown

There is no essential difference between the two international standards, just the difference in color, it should be noted that when connecting the two RJ45 crystal heads, we must ensure that: 1, 2 feet is a winding on, 3, 6 feet is a winding on, 4, 5 feet is a winding on, 7, 8 feet is a winding on. In the same cabling system engineering, only one connection standard can be used. TIA/ eia-568-b standard is commonly used in the production of connector, socket, distribution frame, etc. Otherwise, it should be clearly marked.

Cables shall be terminated with similar connecting devices. For example, class 5e and class 6 connectors are similar in appearance but different in physical mechanism. If a class 5e cable is terminated with a class 3 standard connector or distribution panel, the performance of the cable channel is reduced to class 3. Therefore, in order to ensure the performance of the cable, the module connector must meet the corresponding standards.

Network transmission lines are divided into straight - through lines, cross lines and all - back lines. Direct wires are used to interconnect disparate network devices, such as computers and switches. Cross wires are used to connect devices of the same network, for example, computer to computer. The full-back wire is used to connect the superterminal to the control physical interface of the network device.

RJ45 interface pin definition

There are two common RJ45 interfaces: DTE (data terminal device) types for Ethernet network CARDS, router Ethernet interfaces, etc., and DCE (digital communication device) types for switches, etc. When two devices of the same type communicate using the RJ45 interface, a cross wire connection must be used. If the DTE type interface and the DTE type interface are not cross-connected pins, the pins of the contact are data receiving (sending) pins and cannot communicate. In addition: some DCE type devices will automatically negotiate with each other, at this time, the connection can be through wire or parallel wire.

RJ45 connector performance metrics

The RJ45's performance metrics also include attenuation, near-end crosstalk, insertion loss, return loss, and far-end crosstalk. RJ45 technical specifications: the performance of contact resistance is 2.5 m Ω, insulation resistance for 1000 m Ω, electric strength for DC1000V (AC700V), a minute without breakdown and flashover phenomenon; With gold-plated or silver-plated surface, the connecting diameter is 0.4mm ~ 0.6mm; Plug and socket can be repeatedly plugged and unplugged no less than 750 times; Gold plated 509 (inch) for 8-wire contact needle.

In these performance index requirements, crosstalk is an important factor to be considered in the design. In order to make the whole link have better transmission performance, crosstalk cancellation technology is often used in the socket. Crosstalk cancellation technology can generate crosstalk signals with the same size and opposite polarity as the interference introduced from the plug to offset crosstalk. If the crosstalk interference introduced by the modular plug is represented by "++++", the opposite crosstalk produced by the socket is represented by "--". When the size of two crosstalk signals is equal and the polarity is opposite, the total coupling crosstalk interference signal is zero.

The difference between RJ45 connector and RJ11

ADSL modems at home also have RJ11 ports, which are slightly smaller than the RJ45 ports and are mainly used to connect phone lines. It should be noted that RJ11 interface is 4 or 6 pins, and RJ45 is 8 pins, so RJ45 plug cannot be inserted into RJ11 interface, otherwise RJ11 plug cannot be inserted into RJ45 interface (although it can be realized in physical interface), it must be clearly distinguished in practical use. RJ45 fixed link downward compatible with RJ11, RJ45 3-6, 4-5 line pair corresponding to RJ11 1-4, 2-3 line pair.

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