1.2 tubular transient voltage attenuator (TVS) is a new type of high-performance circuit protection device widely used, with ultra fast response time (sub nanosecond) and quite high overvoltage absorption capacity. When the two ends are directly impacted by high-energy voltage, TVs can change the impedance value between the two ends from high impedance to low impedance at very high speed to absorb instantaneous large current to pull the voltage at both ends to a predetermined value, and protect the following circuit elements from the impact of transient high-voltage jump. Therefore, TV can be used to protect equipment or circuits from transient voltages generated during static and inductive load switching and overvoltage generated by inductive lighting. TV tube is short for transient voltage suppressor. Its characteristics are: the reaction speed is very fast (PS Level); Surge resistance ratio (discharge tube and varistor) μ Low 10 / 1000, pulse power from 400W to 30kW, peak pulse current from 0.52a to 544A; The value range of emergency voltage is 6.8v to 550V, which is convenient for circuits with different voltages. TV lights can be divided into one-way and two-way (the letter after the one-way model is "a", and the two-way model is "CA"). In use, the characteristics of the one-way tube TV and the Zen diode are usually connected in parallel to the protection circuit. In order to limit the current flowing through the TVS tube so that it does not exceed the allowable peak current of the IPP tube, it is necessary to use current limiting elements, such as resistors, self-healing fuses, inductors, etc., It shall be connected in series on the line. Similarly, the characteristics of the TV bidirectional tube are equivalent to the reverse connection of the two central diode series.

2. Varistor varistor is a voltage limiting protective device. Taking advantage of the nonlinear characteristics of the varistor, when overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value to realize the protection of the next circuit. The main parameters of the varistor are: voltage, current capacity, connector capacity, reaction time, etc. The reaction time of the varistor is ns, which is faster than the air discharge tube and slightly slower than the TV tube. Generally speaking, its reaction speed can meet the requirements of electronic circuit overvoltage protection. Varactor is mainly used for DC power supply, AC power supply, low-frequency signal line and antenna power line with power supply. The failure mode of varistor is mainly short circuit. When the overcurrent is too large, the valve plate will also be cracked and open. The varistor has a short service life and its performance will be degraded after multiple impacts. Therefore, the arrester composed of varistors has the problem of maintenance and replacement after long-term use. Learn more about TV tube models and parameters.