In view of the analysis of the characteristics and main parameters of TVS devices along with their working principles, this paper demonstrates that TVS can effectively protect TN power systems, DC power supplies, signal lines, and transistor integrated circuits. These devices are widely applicable and offer a safe and reliable solution for surge protection. A typical application circuit for TVS in various designs is presented. When implementing TVS, it is essential to select matching components based on the specific protection requirements and the related parameters of the circuit.
Power frequency overvoltage, resonant overvoltage, and transient overvoltage in the power grid—such as operating overvoltage and lightning overvoltage—can introduce dangerous surge energy into the internal circuits of electrical equipment. This can disrupt normal operations or even cause damage. Similarly, digital integrated circuits are susceptible to ESD/EFT (electrostatic discharge/electric fast transient burst), which may lead to abnormal operation, system crashes, or even permanent damage. By using TVS devices, circuits can be finely protected, ensuring that sensitive components remain unaffected by various surge pulses. This study provides valuable insights into the detailed analysis and application of TVS devices.
TVS, or Transient Voltage Suppressor, is a high-performance protection device based on Zener diodes. It is typically packaged in a diode-type axial lead structure, with the core being a semiconductor silicon wafer or thin film chip. The chip has two structures: unipolar and bipolar. Unipolar TVS features a single PN junction, while bipolar TVS contains two PN junctions. These junctions are encapsulated in modified epoxy resin after being processed through glass purification.
TVS devices come in unipolar and bipolar types. Unipolar TVS protects against surges in one direction, while bipolar TVS handles surges in both directions, functioning similarly to two Zener diodes connected in reverse. They offer advantages such as low junction capacitance, fast response time, and high power handling capability. Unipolar TVS is commonly used in DC and known-direction signal circuits, while bipolar TVS is suitable for AC and variable signal circuits. TVS arrays are often used for multi-line protection. In some cases, TVS can be connected in series with a diode to reduce parasitic capacitance and protect high-speed signal ports. The serial/parallel configuration should be carefully controlled during application. Environmental factors like temperature changes must also be considered, as they can affect TVS performance by increasing reverse leakage current and reducing power efficiency. TVS devices are available in various power ratings, including 500 W, 1000 W, 1500 W, and 5000 W.
Key parameters of TVS include the minimum breakdown voltage (VBR), rated reverse working voltage (VWM), maximum reverse pulse peak current (IPP), maximum clamping voltage (VC), peak pulse power (Ppp), capacitance (C), reverse leakage current (ID), and clamp response time (TC). VBR is the voltage at which the TVS begins to conduct under test current. VWM is the maximum reverse voltage the TVS can handle without conducting. IPP represents the maximum pulse current the TVS can withstand. VC is the maximum voltage across the TVS when a surge occurs. Ppp is the peak power the TVS can absorb, and it depends on pulse waveform, duration, and ambient temperature. Capacitance affects signal integrity, especially in high-speed applications. ID is the leakage current under VWM, and TC refers to the speed at which the TVS clamps the voltage, typically less than 1 ps.
The volt-ampere characteristics of TVS show that it operates in a high-resistance state until the voltage exceeds VBR, after which it rapidly conducts and clamps the voltage below VC. This makes TVS ideal for protecting downstream circuits from overvoltage events. The clamping characteristics allow the TVS to limit the surge voltage within a safe range, ensuring that the protected circuit remains functional. For example, a surge voltage of 8 kV can be reduced to a safe level of 10 V using TVS, provided the circuit conditions are met.
TVS finds extensive applications in various systems. In TN power systems, two-stage protection is implemented using MOV and TVS to suppress surges entering via power lines. In network signal lines, GDT and TVS are combined for fast response and minimal signal interference. In DC power systems, TVS protects rectifier outputs and prevents overvoltage damage. In transistor circuits, TVS is placed at input and output terminals to guard against ESD/EFT. TTL and MOS circuits also benefit from TVS protection, ensuring stable operation and preventing damage to critical components.
In conclusion, TVS offers numerous advantages, including fast response, high power, low capacitance, small size, and no leakage current. It is effective in protecting a wide range of systems from various surge events, including power line surges and ESD/EFT. When designing circuits, it is crucial to consider the characteristics of the protected circuit and select appropriate TVS devices based on parameters like VC, IPP, VWM, VBR, and Ppp. Proper integration ensures that the TVS does not interfere with normal operations but effectively discharges surges and clamps dangerous voltages within safe limits.
Monitor Stand For Computer Screens
Shenzhen ChengRong Technology Co.,Ltd. , https://www.laptopstandsupplier.com