Functions of Network Transformer

Data mercury is also called a Network Transformer or a network isolation transformer. It plays two main roles in one network card. One is to transmit data. It filters the difference signal sent by the PHY using the difference mode coupled coil to enhance the signal, in addition, the electromagnetic field is switched to the other end of the connected network cable at different levels. The first is to isolate different levels of different network devices connected by the network cable, so as to prevent different voltages from being transmitted through the network cable to damage the device. In addition, data mercury can also protect the equipment against lightning.

When the signal voltage (differential mode signal) is added to the two ends of the transformer, the Inductive voltage is induced at the secondary end of the transformer by magnetic circuit coupling. For signal voltage, because the signal current flowing through both the CMC winding is of the same size and opposite direction, the opposite magnetic flux is generated in the CMC Core magnetic circuit to offset each other, differential Mode signal transmission is not affected. At this time, the two windings of the CMT flow through the same size and direction of the current, so that the role of the CMT is equivalent to a large resistance, blocking the passing of the differential mode signal, it has little impact on the transmission of carrier signals. Therefore, the differential mode signal is directly coupled to the load. For common-mode signals, the distribution capacitance between the initial and secondary transformers is coupled to the secondary one. At this time, the CMC two winding flows through the same size and direction of the current, at this time, CMC is equivalent to a large resistor to prevent the transmission of common mode current, while the two CMT winding is the same size, the opposite direction of the current, the common mode signal is equivalent to a short circuit, in this way, the common mode voltage is basically not transmitted, but coupled to the load. In this way, both the carrier signal can be transmitted well and the common mode interference signal can be suppressed.

The middle part of the transformer. Why is there some power supply in the middle head? Some grounding? This is mainly determined by the use of the PHY chip UTP (twisted pair wire) Port Drive type, there are two kinds, if it is voltage-driven, it will be connected to the power supply; if it is a current-driven, it will not be used, directly connect a capacitor to the ground. Why are some requests connected to 2.5 V? And some are connected to 3.3v? This is determined by the UTP port level specified in the PHY chip information. If it is 2.5 V, it will be pulled up to 3.3 V, if it is 3.3v, it will be pulled up to v.