“How to choose the most suitable circuit protection device? Do you know? With the development of science and technology, power/Electronic products are becoming more and more diverse and complex, and the circuit protection components used are not the simple glass tube fuses of the past, usually protecting devices There are varistors, TVS, gas discharge tubes, etc. Has developed into a wide range of emerging electronic components field. Then, the correct selection of circuit protection devices is extremely important. Can engineers do it 100%?

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How to choose the most suitable circuit protection device? Do you know? With the development of science and technology, power/electronic products are becoming more and more diverse and complex, and the circuit protection components used are not the simple glass tube fuses of the past, usually protecting devices There are varistors, TVS, gas discharge tubes, etc. Has developed into a wide range of emerging electronic components field. Then, the correct selection of circuit protection devices is extremely important. Can engineers do it 100%?

Overvoltage, overcurrent, surge, electromagnetic interference, electrostatic discharge, etc. have always been the focus of circuit protection. Therefore, the mainstream circuit protection devices in the market are also based on lightning protection/overvoltage/overcurrent/anti-static. Common Protection devices include ceramic gas discharge tubes, solid state discharge tubes, transient suppression diodes, varistors, resettable fuses, and ESD electrostatic diodes.

How to correctly choose the most suitable circuit protection device:

1. You need to know what damage you want to prevent. Many times design engineers will ask questions about surge protection devices, but they don’t know what damage they want to avoid. Therefore, the first thing you must do Determine whether to prevent direct lightning strikes, secondary shocks (as described in the IEC61000-4-5 standard), or electrostatic discharge (as described in the IEC61000-4-2 standard). Once a decision is made, you can select the appropriate circuit protection device.

2. Decide what outcome you want when a failure condition occurs. For example, you want to be able to tolerate failure conditions at runtime and remain operational during and after the failure conditions. Tolerating fault conditions only when shutting down and then entering operation the next time the device is powered up, or providing protection to safely fail the device and not need to operate after the failure is over? The circuit protection device you choose depends on answers to these questions.

3. We need to make reasonable assumptions about what is “normal” and “abnormal” operation. For example, you cannot choose an overcurrent protection device that operates at 6A, but expect your design to operate normally at 5.99999A. That’s simply not enough headroom. If your design consumes 6A under normal operation, you must choose an overcurrent protection device PTC resettable fuse that operates at 8A or higher. Not only that, but you must know the maximum operating voltage, maximum ambient temperature, as well as fault voltage, fault current and fault duration to make the right choice.

4. It must be clear that any protection is impossible to achieve 100%, if you design to protect a specific event, but there is always the possibility of some more serious events. For example, telecommunications lightning regulations describe hazards that are much less severe than direct lightning strikes, and it is possible, but very expensive, to protect products from direct lightning strikes.

5. The circuit protection scheme should be planned at the beginning of the design. Although the circuit protection devices are much smaller than in the past, after the PCB design is completed, it is impossible to add circuit protection devices if there is not enough space. With the development of science and technology, power/electronic products are increasingly diversified and complex, and the circuit structure and physical size of electronic products become smaller and smaller, and it becomes more important to design circuit protection in the early stage of the design cycle.

Circuit protection and electronic protection device selection may seem like a low priority, but design should be started early to eliminate design issues and ensure the performance and reliability of your product.