Protection scheme of TVS tube SM8S series on car power line

Automotive safety has always been one of the key concerns of automotive electronics engineers. As we all know, the working environment of automobiles is extremely harsh. Electronic control units, infotainment systems, sensors and other automotive electronic devices are connected to a power cord, and all automotive The power source of electronic equipment products is the engine and the battery. Since the engine and battery are susceptible to temperature, operating conditions, and other conditions, they fluctuate. At the same time, the use of solenoid-loaded automotive systems such as fuel injection systems, valves, motors, electrical and hydrolysis controllers can introduce ESD, noise spikes, and other types of transient and surge voltages onto power and signal lines.

Protection scheme of TVS tube SM8S series on car power line

To this end, one of the heavyweight challenges in automotive design is: how to protect automotive electronics from high surge voltages, transients, ESD and noise on power lines? The birth of the SM8S series transient suppression TVS diodes has become an ideal protection component for automotive electronic equipment. Next, I will mainly introduce the primary and secondary protection applications of TVS tube SM8S series in automotive power lines.

TVS tube SM8S series, how much do you know? SM8S series TVS diodes meet the AEC-Q101 certification standard, and can pass the ISO 7637-2 5a/5b and ISO 16750 load dump test requirements, with high reliability and high stability, and are widely recognized and favored by the majority of automotive suppliers. At the same time, we provide free selection, testing, and sample services, and it is clear at a glance whether the quality is good or not; moreover, we can also customize the production of electronic components that meet customer needs according to customer needs. Your circuit is safer.


The SM8S series of load-shedding TVS tubes for primary protection of automotive power lines can be divided into two categories: epitaxial and non-epitaxial. In reverse-biased mode, they have similar breakdown characteristics; the difference is that epitaxial TVS tubes have low forward voltage drop characteristics in forward mode, and non-epitaxial TVS tubes have positive voltage drop characteristics under the same conditions. The pressure drop is relatively high. This feature is especially important for reverse voltages applied to the power lines. In the reverse power input mode, the power line voltage is the same as the voltage of the forward voltage drop of the TVS tube. In this case, it is easy to cause electronic circuit failure. At this time, the low forward voltage drop of the epitaxial TVS tube can solve this problem well. question. Of course, there are other ways to protect the circuit from reverse power input damage. Interested partners can communicate with Dongwo Electronics FAE engineers.


The primary object of protection circuits in automotive systems is high surge voltages, but the clamped voltages are still high. For this reason, secondary protection is especially important in 24V powertrains, such as those found in trucks and vans. The main reason for this is because most voltage regulators and DC-DC converter ICs have a maximum input voltage of 45V-60V. In this case, it is recommended to increase the resistance on the power line to reduce the transient current. In this case, a TVS tube with a smaller rated power can be used as the secondary protection.

Different types of circuit protection components are required for different automotive electronic equipment. For specific circuit protection scheme design, protection component selection, product testing and other services, you can consult professionals in related fields.

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