A Network Transformer will be added in the middle when the Ethernet device is connected to RJ45 through the phy. What is the role of this transformer? Theoretically, transformer can be directly connected to RJ45 without being connected. However, the transmission distance is very limited, and when connected to different levels of Network Ports, it will also affect. In addition, the external interference to the chip is also great. After a network transformer is connected, it is mainly used for signal level coupling. First, the signal can be enhanced to make the transmission distance farther. Second, the chip end is isolated from the external end, and the anti-interference capability is greatly enhanced, in addition, the chip is greatly protected (such as lightning strikes). Third, when connected to different levels (for example, some PHY chips are 2.5 V, and some PHY chips are 3.3 V) does not affect each other's devices.
Is the internal structure of Gigabit Ethernet transformer datasheet:
In general, network transformers are mainly used for signal enhancement, signal clutter suppression, and high voltage isolation.
