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People often ask: What are the common issues in EMS immunity design for EMC? Here are the frequently asked questions:
1. In automotive electronics EMS design, how to choose a suitable microcontroller to reduce electromagnetic radiation? What are the differences in electromagnetic compatibility between different brands and models of microcontrollers?
»»» In automotive electronics EMS design, microcontroller (MCU) selection needs to focus on reducing high-speed switching noise and optimizing clock radiation. Core strategies include:
· Prioritize MCUs with low EMI characteristics: Need to pay attention to...

1. What are the immunity testing requirements for common mode inductors in IEC 61000-4-6 standard?​
2. What are the conducted emission suppression requirements for common mode inductors in information technology equipment per CISPR 22 standard?​
3. What is the classification basis for the insulation system of common mode inductors in UL 1446 standard?​

1. What challenges does common mode inductor design face in millimeter-wave devices?
2. What are the material options for bendable common mode inductors in flexible electronic devices?
3. What are the application prospects of superconducting common mode inductors in extreme environments?

China: Risk Classification System for Categories I, II, and III
According to the Medical Device Regulation (MDR 2017/745), the European Union classifies medical devices into Class I, Class IIa, Class IIb, and Class III, with risks gradually increasing

​1. What are possible reasons for severe heating of common mode inductors? How to troubleshoot?​
Answer: Possible reasons:

Excessive differential mode current: Common mode inductors have weak suppression capability for differential mode current. If differential mode current in the circuit exceeds design values, it increases copper loss (I²R) in windings, causing heating.
Core saturation: When common mode current or differential mode current is too high, magnetic flux density in the core exceeds saturation point, permeability drops sharply, and eddy current losses increase dramatically, causing core heating.
· Abnormal winding resistance: Winding wires are too thin, local short circuits or poor contact during winding.

What is the area with the most frequent lightning activity in the world? It is Lake Maracaibo in Venezuela Core data and phenomenon characteristics According to NASA's research, Lake Maracaibo experiences an average of 233 lightning strikes per square kilometer per year, far exceeding other regions. This data is 1.5 times that of the Congo Basin (recorded 158 square kilometers per year in Kifka village in 2004) and is also the "Lightning Capital" of Florida, United States; Orlando approximately 10 times per square kilometer per year

1. What fixture should be used for insertion loss testing of common mode inductors? Why?​
Answer: Insertion loss testing of common mode inductors typically uses 50Ω standard coaxial fixtures (such as BNC or SMA interface fixtures), and in some scenarios, they are used in conjunction with LINE IMPEDANCE STABILIZATION NETWORK (LISN). Reason: According to EMC testing standards (such as CISPR 16, IEC 61000-4-6), the characteristic impedance of the testing system needs to be unified to 50Ω.

​Question 1. How to optimize interference suppression above 10MHz through the combination of common mode inductors and Y capacitors?
Answer: Common mode inductors suppress interference through high common mode impedance from low to medium-high frequencies (e.g., below 1MHz), but at high frequencies (above 10MHz), impedance decreases due to parasitic capacitance (between windings, between windings and core), weakening suppression effect. Y capacitors (usually ceramic capacitors, such as MLCC) have low equivalent series resistance (ESR) and parasitic inductance (ESL), providing low impedance paths in high-frequency bands to divert common mode interference to ground. Optimization methods:
Capacitance selection:

The current US tariff strategy is based on a core fallacy that misjudges the complex reality of the global semiconductor industry. This self inflicted wrong policy did not lead the United States to victory, but instead resulted in strategic failure in its technological competition with China