Class-X and Class-Y capacitors are safety-certified and generally designed and used in AC line filtering in many electronic device applications. X and Y capacitors not only keep radio frequency noise generated by the device local to that device, but also protect the device from mains noise and high voltage. This guide explains the classification system, selection criteria, and practical application of X and Y safety capacitors for EMI/EMC filtering. Switch-mode power supplies, motor drives, LED drivers, and other power electronics generate high-frequency noise as a byproduct of their switching. That's why safety capacitors are essential for mitigating the risks associated with transient voltages and electrical interference. Common applications include modems, automotive electronics, and power supplies, enhancing user safety and device reliability.
[pdf] 