Shielding structure, circuit and power adapter

Abstract

A variety of shielding structures, circuits and power adapters. In the present invention, two shielding layers are arranged between the rectifying filter capacitor and other components in the circuit, and one of the shielding layers is connected to the secondary ground SGND of the circuit, and the other shielding layer is connected to the secondary ground SGND of the circuit. The present invention can utilize the circuit connection relationship of the shielding structure, so that the equivalent parasitic capacitance between the rectification filter capacitor and the shielding layer is no longer connected in parallel with the common mode inductance in the circuit. Therefore, when the present invention works in a high-frequency state, the impedance characteristic of the common-mode inductor is less affected by the parasitic capacitance, and the common-mode inductor will not lose its effect on high-frequency noise due to the influence of the parasitic capacitance. The shielding structure of the present invention is suitable for DC filters, AC filters, AC-DC mixed-mode filters and power adapter circuits, and can effectively ensure the suppression of high-frequency common-mode noise in the circuits.

Description

technical field [0001] The invention relates to electromagnetic interference shielding technology, in particular to a shielding structure, circuit and power adapter. Background technique [0002] In the circuit structure of the power adapter, due to the near-field coupling between the devices, parasitic capacitance distribution will be generated between the devices. Each parasitic capacitance is equivalently connected in parallel at both ends of the common mode inductance of the power adapter. [0003] The common-mode inductor in the power adapter is designed to suppress common-mode noise. Theoretically, the greater the impedance of the common-mode inductor itself, the higher the degree of suppression of the common-mode noise in the adapter circuit, and the interference caused by the common-mode noise can be reduced as much as possible. However, due to the distribution of parasitic capacitance, in the equivalent circuit of the power adapter, the common-mode inductance actu...

AI Technical Summary

Problems solved by technology

[0005] In extreme cases, when the circuit operates at high frequency, the distribution of the above-mentioned parasitic capacitance will basically make the common-mode inductance invalid, so that the impedance of the overall circuit after parallel connection is reduced, which is not conducive to suppressing the common-mode noise in the circuit

Images