Why is the clamping voltage of the TVS tube slightly higher than the chip voltage?
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Why is the clamping voltage of the TVS tube slightly higher than the chip voltage?

Posted Date: 2024-02-06

Why is the TVS tube (transient suppression diode) slightly higher than the chip voltage? Generally speaking, the clamping voltage is higher than VBR. Will it burn the chip?

TVS tube (Transient Suppression Diode) is a device used to protect sensitive electronic components in circuits from overvoltage impacts. It conducts its current quickly during overvoltage conditions to protect equipment in the circuit. In this article, we will discuss in detail why the clamping voltage of TVS tubes is slightly higher than the chip voltage, and explain how they work to prevent the possibility of chip burnout.

First, let us understand the basic working principle of TVS tube. TVS tube is a specially designed diode with a PN junction, usually made of silicon material. Unlike ordinary diodes, TVS tubes have higher breakdown voltage and faster response time. When a forward voltage is applied to the TVS tube, it behaves like a normal diode and current flows through it. However, when the reverse voltage exceeds the set breakdown voltage, the TVS tube will quickly become low resistance and conduct current, thereby shunting the overvoltage to the ground.

Now let us discuss why the clamping voltage of the TVS tube is slightly higher than the chip voltage. The clamping voltage (also called breakdown voltage) is the maximum reverse voltage of the TVS tube before current passes through it. This value is usually slightly higher than the working voltage of the chip to ensure that the TVS tube can absorb overvoltage from the circuit before the voltage breaks down the sensitive components. This can help prevent the chip from being damaged or burned due to overvoltage. In fact, it is precisely because of this clamping voltage that is higher than the chip voltage that the TVS tube can better protect the chip. Considering the way it works, the clamping voltage of the TVS tube needs to be higher than the chip voltage to ensure that the overvoltage is shunted out of the circuit in time.

So, is it possible to burn the chip? In fact, TVS tubes are usually designed to withstand higher voltages than the chip can withstand. This is to ensure that when an overvoltage event occurs, the voltage can be shunted to the TVS tube without causing damage to the chip. TVS tubes usually have high power tolerance and fast response time, and can effectively absorb overvoltage and shunt it to ground.

However, despite the high fault tolerance of TVS tubes, the chip still needs to incorporate appropriate protection measures into the circuit design. This may include using appropriate current limiters, fuses or thermistors to limit voltage and current. In addition, proper layout and ground design is important to ensure that overvoltage events have appropriate ground and discharge paths.

To sum up, the clamping voltage of the TVS tube is slightly higher than the chip voltage to ensure that the overvoltage is diverted out of the circuit in time and protects the chip. TVS tube is a diode specially designed for over-voltage protection, with high breakdown voltage and fast response time. Although they can usually prevent the chip from being burned out, other protective measures are still needed in the circuit design to ensure the overall stability and reliability of the system.


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