Overview

Transient Voltage Suppression diodes (Transient Voltage Suppression diodes), also known as TVS diodes, are the simplest circuit protection option to improve EMI and ESD immunity. They have fast response time, high transient power, low leakage current, and breakdown voltage. It has the advantages of small deviation, easy control of clamping voltage, no damage limit, and small size. TVS diodes are mainly used in automotive electronics, computer systems, communication equipment, instrumentation, new energy, data centers, AC/DC power supplies, drones, robots and other fields.

IC chip protection circuit

In product circuit design, several matters that should be considered include: internal IC and external TVS protection circuit, switching voltage of TVS diodes, diode array, common mode compensation voltage, backward drive protection, and differential input and output, etc. Among them, TVS diodes can reduce the surge voltage on the IC. Many ICs have internal protection circuitry to protect against ESD failures; however, this is often insufficient for surge events.

For application engineers, the best way to deal with damage to devices caused by transient pulses is to divert the transient current away from sensitive devices (such as IC chips). To achieve this purpose, the TVS is generally connected in parallel with the protected circuit during PCB wiring. In this way, when the instantaneous voltage exceeds the normal operating voltage of the circuit, the TVS will undergo avalanche breakdown, thereby providing an ultra-low impedance path for the instantaneous current. As a result, the instantaneous current is diverted through the TVS to avoid the protected device, and Keep the protected circuit at cut-off voltage until the voltage returns to normal. After that, when the instantaneous pulse ends, the TVS diode automatically returns to the high resistance state, and the entire circuit enters the normal voltage state.

ESD protection circuit

The surge resistance capability of silicon TVS diodes is directly related to its size and external components, which is generally more than 10 times the size of the internal IC TVS. The reason why an external TVS diode can provide a high level of surge protection is because the TVS diode not only protects the IC, but provides greater protection. In addition, the internal protection circuitry of most ICs can only deal with a small number of ESD events, while external TVS devices can provide unlimited surge immunity.

It is worth noting that understanding the internal protection circuitry of the IC is very helpful in selecting the power rating and switching voltage of the external TVS device. Unfortunately, many IC data sheets only provide nominal ESD and do not disclose the internal protection circuitry. In fact, the internal protection circuit can be designed using common electronic components such as high-voltage transistors, Zener diodes, diode arrays, thyristors, and overvoltage detection switches. It can be seen that TVS diode is a convenient and practical circuit protection device. Users only need to follow a few simple rules to achieve effective surge protection function. The only regret is that TVS diodes are large in size. I believe that with the development of material technology, this problem will be solved.

More information

Semiware provides a full range of ESD static suppressor products, which you can access at any time through the official Semiware link page: https://semiware.com/ If you have technical questions, please contact the technical support engineer as follows: Email: Fae01 @semiware.com;

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