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All colleagues unite and focus their efforts to write a new chapter of developmentTo resolve interference issues with power adapters, try the following methods!
所属分类： Industry News
发布时间：2020-06-08
Power adapter During operation, external factors may sometimes cause interference. So how should we address such interference?
External interference generated by power adapters—such as harmonic currents in the power cord, conducted disturbances on the power line, and electromagnetic radiation—can only be mitigated through measures aimed at reducing such disturbances. On the one hand, this can be achieved by enhancing the design of input/output filter circuits, improving the performance of active power factor correction (APFC) circuits, minimizing the rate of change of voltage and current in switching transistors and rectifier/ freewheeling diodes, and adopting various soft-switching topologies and control strategies. On the other hand, it involves strengthening the shielding effectiveness of the enclosure, reducing leakage through gaps in the chassis, and ensuring proper grounding.
With regard to external electromagnetic interference—such as surges and lightning strikes—the surge‑protection capabilities of the AC input and DC output ports should be optimized. For lightning protection, a combination of zinc oxide varistors and gas discharge tubes can be employed. As for electrostatic discharge (ESD), TVS diodes and appropriate grounding measures should be used; additionally, increasing the clearance between low‑signal circuits and the enclosure, or selecting components with built‑in ESD‑mitigation features, can help address this issue.
To minimize internal interference in a power adapter, address the following aspects: ensure single-point grounding for digital and analog circuits, as well as for high‑current circuits and low‑current circuits—particularly current‑ and voltage‑sensing circuits—to reduce common‑impedance coupling and ground‑loop effects; when routing traces, maintain adequate spacing between adjacent lines and consider signal types to avoid crosstalk; lower ground‑path impedance; reduce the loop area of high‑voltage, high‑current paths, especially those formed by the transformer primary winding, switching transistors, and power‑filter capacitor circuits; decrease the loop area of output rectifier and freewheeling diode circuits together with the DC‑filter circuit; minimize transformer leakage inductance and the parasitic capacitance of filter capacitors; and employ filter capacitors with higher resonant frequencies, among other measures.
In terms of signal‑path design, appropriately increasing the use of high‑interference‑immunity TUS devices, high‑frequency capacitors, ferrite beads, and similar components can enhance the noise‑rejection capability of low‑signal circuits. For low‑signal circuits located close to the enclosure, adequate insulation and dielectric‑strength treatments should be implemented. The heat sinks of power devices and the electromagnetic shielding layers of the main transformer must be properly grounded. Large‑area grounding between control units should be achieved using dedicated ground planes for shielding. On the rectifier rack, considerations should include inter‑rectifier electromagnetic coupling and the overall system grounding scheme to improve the operational stability of the power adapter.
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Power adapter , Charger manufacturer: Shenzhen Suoyuan Technology Co., Ltd.!