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One article on understanding the differences between EMC, EMI, and ESD



One article on understanding the differences between EMC, EMI, and ESD

ESD, EMI, and EMC design are common challenges encountered by electronic engineers in design. Electromagnetic compatibility (EMC) refers to the ability of a device or system to operate in its electromagnetic environment in compliance with requirements without causing intolerable electromagnetic interference to any device in its environment.

Therefore, EMC includes two requirements: on the one hand, it means that the electromagnetic interference generated by the equipment to the environment during normal operation cannot exceed a certain limit; On the other hand, it refers to the equipment having a certain degree of immunity to electromagnetic interference present in the environment, that is, electromagnetic sensitivity. The so-called electromagnetic interference refers to any electromagnetic phenomenon that can degrade the performance of equipment or systems. The so-called electromagnetic interference refers to the performance degradation of equipment or systems caused by electromagnetic interference.

EMC includes two parts: EMI and EMS. EMI refers to the electromagnetic noise generated by the machine itself during the execution of its intended functions, which is detrimental to other systems; EMS refers to the ability of a machine to perform its intended functions without being affected by the surrounding electromagnetic environment.

In the design of electronic products, it is important to conduct EMC design to achieve good EMC performance and cost ratio; The EMC performance of electronic products is given by design. Testing is simply a quantitative method to characterize the inherent EMC performance of electronic products.

Firstly, consider EMC design in the early stages of research and development

If EMC issues are not considered in the early stage of product design and only hope to be resolved during the testing phase (manifested as solving EMC issues in the designed and formed products through rectification, a large amount of manpower and material resources are invested in the later testing/verification, and rectification phase). So, even if the product rectification is successful, in most cases, it will still lead to a significant increase in research and development costs and a significant extension of the cycle due to changes in circuit principles, PCB design, and structural molds involved in the rectification. Only by considering and predicting EMC issues in the early stage of product design, and turning EMC into a controllable design technique that is parallel and synchronized with the process of product functional design, can the product be designed in one go.

Secondly, EMC design should be systematically carried out

Improving the EMC performance of electronic products through design is definitely not something that a single EMC expert in the enterprise can assign, because EMC cannot exist without the physical hardware, structure, and other aspects of the product. Therefore, in order to achieve good EMC performance in the design of electronic products, it is necessary to improve the EMC experience and awareness of product design engineers.

As a hardware engineer, in addition to the necessary knowledge of circuit design, one should also master the basic knowledge of EMI and EMS anti-interference design; PCB design engineers need to master EMC design knowledge in device layout, cascading design, and high-speed wiring; Structural engineers also need to have knowledge in the design of shielding and other aspects of product structure. Because these engineers who participate in product design together need to understand and comprehend the mysteries of the suggestions put forward by EMC experts in the product design process, and combine them with the design characteristics of their respective fields to eliminate the germ of all EMC problems in the product design stage. Only when all developers involved in product design work together to improve their EMC skills can electronic products with high-performance EMC be designed.

If EMC issues are not considered in the design of general electronic products, it can lead to EMC testing failure and result in failure to pass relevant regulatory certifications. The following figure outlines the key points of EMC, EMI, and ESD reviews.

With the development of electrical and electronic technology, household appliances are becoming increasingly popular and electronic. With the development of broadcasting, television, postal communication, computers and their networks, the electromagnetic environment is becoming increasingly complex and deteriorating. We are gradually paying attention to the working environment of equipment and the impact of electromagnetic environment on electronic devices. The issues of electromagnetic interference (EMI) and electromagnetic compatibility (EMC) in electrical and electronic products are receiving increasing attention from engineers and production enterprises.

In ESD protection, it can be broadly divided into two categories:

1. Conductive ESD protection

The protection of electrostatic current in circuits mainly uses some protective devices, which form a protective circuit at the front end of sensitive devices to guide or dissipate current. Such protective devices include ceramic capacitors, varistors, TVS tubes, etc.
2. Radiation induced ESD protection

For the impact of static electricity on sensitive circuits, the main protection method is to minimize the generation and energy of the field as much as possible, increase the protection ability through structural improvement, and implement protection for sensitive circuits. The protection of the field is usually difficult, and a method called allotrope has been explored in improvement practice. By effectively grounding, the shell forms a body with the same potential to suppress discharge. The fact proves that this method is effective and easy to implement.

There are many general methods for protecting against static electricity, including reducing the accumulation of static electricity; Insulate the product to prevent static electricity from occurring; Provide branch shunt electrostatic current for sensitive circuits; Shielding the circuit in the discharge area; Reduce the loop area to protect the circuit from the magnetic field generated by electrostatic discharge. There are both direct discharge and coupling for correlated fields.

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