Electromagnetic compatibility is an issue that needs to be considered at the beginning of the design of every electronic product, and it is also a topic that must be met before leaving the factory. The impact of power technology on electromagnetic compatibility is the most important part, so discussing electromagnetic compatibility cannot be separated from power technology. Thank you for the careful arrangement of these two important topics by Electric Extreme.

The conference invites 12 technical application experts to share 12 practical knowledge topics related to electromagnetic compatibility, power technology, signal integrity, standards, and components. Here, I would like to share my learning and insights gained from attending this seminar.

一、 The Essence of EMC brought by Teacher Zheng Junqi

Teacher Zheng explained EMC in a simple and easy to understand manner. Below is an excerpt of the main content.

First of all, let me know: "Has your product passed?" Haha!

1. The three elements of EMC: interference source, coupling path, and interfered object

Electronic products include: wireless products and non wireless products. Wireless products should eliminate interference sources from non wireless products; Non wireless products need to improve their anti-interference ability. Therefore, the EMC standard includes EMI+EMC.

2. The "dual cycle" mechanism of signals

Functional signal

3. Problem solving

Identify the cause of the problem and find a solution to the problem. The formation of EMC problems is a process of signal transmission, rather than individual point problems. Solving problems requires going from point to surface.

4. EMC testing

EMC testing is an exam for product EMC design, with a maximum score of 100 and a passing score of approximately 60.

After listening to Teacher Zheng's lecture on EMC, I was enlightened and broadened my thinking on solving EMC problems. So, has your product passed?

2、 Shanghai Lei Mao Hu Guangliang's presentation on "Application of New Flyback TVS Devices in Power Supply and Signal"

 This is a novel topic that has attracted the high attention of more than 300 engineers attending the meeting. As Mr. Hu explained, the engineers raised their phones to take photos and records. After the explanation, they scanned the QR code to prepare for a detailed understanding.

Here is an excerpt of the main content.

Teacher Hu first explains what TVS ESD is?

TVS diodes are used to protect the backend IC from unexpected overvoltage and surge caused by static electricity and power fluctuations.

Then the difference between TVS and ESD was introduced.

3. Then explain how to choose TVS and ESD

4. Sometimes when we use TVS and ESD backend, we still can't get protection. What should we do?

At this point, we can choose to bring back the scanned TVS and ESD because their clamping voltage is low.

The left side of the above figure shows the VI curve of the swept TVS, while the right side shows the VI curve of a regular TVS.

Summarizing the advantages of TVS scanning: firstly, lower clamping voltage provides better protection for backend circuits; secondly, with the same packaged power, it can absorb larger surge currents, resulting in a larger IPP and stronger surge resistance.

For example, a comparison of a 600W 33V TVS is shown in the following figure

Above is the TVS 6LM33CA brought back for scanning, and below is the regular TVS SMBJ33CA.

The VC of 6LM33CA brought back for scanning is 30.1V, while the VC of SMBJ33CA below is 53.3V, which is 23V higher than that of flyback. For current IPP, 6LM33CA is 26.32A, and SMBJ33CA is 11.3A, which is 15A higher. From these data analyses, it can be seen that bringing back the sweep TVS protection circuit has more advantages.

It can be said that bringing back the TVS scanner has brought new equipment to engineers for solving static surge protection.

三、Teacher Du Zuobing brings "EMC Research and Optimization of Energy Storage Power Supply" and Teacher Huang Baoxiang brings "EMC Debugging and Design Optimization of Inverter"

These two teachers are experts in this field, and the most important insight I gained from listening to their lectures is that EMC problems first need to find the root cause, and solving the problem will be easy. Sometimes, it is not necessary to add heavyweight components such as filters, only a capacitor is needed to solve the problem.

What the two teachers are saying is the same as what Teacher Zheng Junqi is saying. We need to let the interference signal inside the product circulate internally and not let it slip out. External interference signals from the product should not be allowed to enter, and should not be transmitted to any location. So the signals coming out of the product need to be filtered at the interface to remove interference signals and allow clean signals to come out. In order to prevent interference from entering the interior of the product when external signals enter, filtering should also be applied at the interface to filter out interference signals and allow functional signals to enter.

As long as new products are launched, EMC is always an endless topic for us to discuss, and EMC learning is always on the way.