UU common mode inductance
Product Description: Common mode choke, also called common mode choke, is often used in computer switching power supplies to filter common mode electromagnetic interference signals. In the board design, the common mode inductor is also used for EMI filtering
Common mode inductance (common mode choke), also known as common mode choke, is a commonly used method of filtering common mode EMI signals in computer switching power supplies. In the design of the circuit board, the common mode inductance also plays a role of EMI filtering to suppress the electromagnetic waves radiated by the high-speed signal line.
Common mode inductance filter circuit, La and LB are common mode inductance coils. The two coils are wound on the same iron core with the same number of turns and phase (reverse winding). In this way, when the normal current in the circuit flows through the common-mode inductor, the current will generate a reverse magnetic field in the inductance coils wound in the same phase and cancel each other out. At this time, the normal signal current is mainly affected by the coil resistance (and a small amount of damping caused by the leakage inductance); when there is a common mode current, the current will be compensated by the coil resistance
When the current flows through the coil, due to the isotropy of the common mode current, the same magnetic field will be generated in the coil, which increases the inductive reactance of the coil, which makes the coil exhibit high impedance and produces a strong damping effect, thereby attenuating the common mode current to Purpose of filtering.
In fact, if one end of the filter circuit is connected to the interference source, and the other end is connected to the interfered device, La and C1, LB and C2 form two sets of low-pass filters, which can control the common mode EMI signal on the line to a very low level. s level. The circuit can not only suppress the external EMI signal, but also attenuate the EMI signal generated by the circuit itself, effectively reducing the intensity of EMI interference.
Domestic small common mode inductors have the advantages of suppressing high frequency noise, common mode choke coil structure, no signal attenuation, small size, convenient use, good balance, convenient use, and high quality. It is widely used in double-balanced tuning devices, multi-frequency transformers, impedance transformers, balanced and unbalanced transformation transformers, etc.
There is also a common mode filter inductor/EMI filter inductor, ferrite core, two-wire winding, good noise suppression measures, high common mode noise suppression, low differential mode noise signal suppression, low interference source, and not easy to deform in high-speed signals , Small size, good balance, easy to use, and good quality. It is widely used in EMI noise suppression of electronic equipment, personal computer and peripheral equipment USB lines, DVC IEEE1394 circuits, set-top boxes, LCD panels, low-voltage differential signals, etc.