RJ45 transformer, also known as filters, isolation transformers, they are integrated isolation transformer and widely used in RJ45 connector. This product is mainly used RJ45 Ethernet, network routers, Ethernet switches, VDSL digital equipment, network set-top boxes, ADSL, EPON / GPON triple play equipment, EOC terminal, intelligence TV, PC boards and other industrial equipment.RJ45 transformer consists of transformer, capacitor center tap, auto-transformers, common mode inductance, it has five types, single port, dual-port, multi-port, 10 / 100BASE and 1000BASE-TX. Ethernet device connections have an important function, such as high voltage isolation, impedance matching, noise suppression and signal transmission. Generally, RJ45 network transformer are not necessary components of RJ45 connectors, because it can also work if it is not equipped with RJ45 network transformer, but will be subject to certain restrictions, such as the transmission distance, also it cannot be compatible with different electrical frequency network port and so on.In standard design, RJ45 transformer is located between RJ45 interface and PHY chips, focusing on coupling to the signal level, some of center-tapped transformer will connect power, voltage is generally 1.8V, 2.5 V and 3.3 V, and some will directly connect to ground, usually based on the way of UTP drive and type of PHY chips to determine the connection. The center tap of voltage driver need to connect with power, and for the current drive will be connected directly with capacitor then to ground. In addition, different PHY chip will make the design and datasheet different, user should refer to the center tap of chip type to determine the connection method, especially should pay attention when connect to power supply, it should refer to UTP connect port according to PHY chips design to determine the voltage connection.RJ45 transformer has many function, such as Ethernet signal transmission can be guaranteed without distortion, inhibition of radiation emission to meet the IEEE802.3 standard for electrical isolation requirements. RJ45 network transformer applications wiring, grounding, shade, filters, spatial separation counseling and other techniques for processing, the chip connection portion and isolated from the outside, effectively blocking external interference, increasing the protective effect, such as prevent lightning strikes...etc. these kinds of factors to cause the chips into huge damage, also the transmission signal strength increases, improve the transmission distance; increase the practicality and adaptation of the connector, so network interface is more convenient, comfortable, reducing user burden, achieve multiplier effect.In summary, although RJ45 transformer only an optional tiny components, but they can greatly enhance the performance and practicality of the RJ45 connector, it's significant in the transmission of information and security performance, it is a very important components.