TVS (Transient Voltage Suppressor) diodes, also known as transient suppression diodes, are commonly used as a new type of high-efficiency circuit protection device. They have a very fast response time (sub-nanosecond level) and a relatively high surge absorption capability. When it is subjected to an instantaneous high-energy shock at both ends, the TVS can change the impedance between the two ends from a high impedance to a low impedance at an extremely high speed to absorb an instantaneous high current and clamp the voltage across it. A predetermined value to protect the following circuit components from transient high voltage spikes. The working principle of TVS device: Transient (transient) voltage suppression diode is abbreviated as TVS device. Under the specified reverse application condition, when it is subjected to a high-energy transient overvoltage pulse, the working impedance can be reduced to very low immediately. The conduction value allows large currents to pass and clamps the voltage to a predetermined level, thereby effectively protecting the precision components in the electronic circuit from damage. TVS can withstand instantaneous pulse power up to kW, and its clamp response time is only 1ps (10^-12S). The forward surge current allowed by TVS can reach 50-200A at T=25°C, T=10ms. The bidirectional TVS can absorb instantaneous large pulse power in both positive and negative directions and clamp the voltage to a predetermined level. The bidirectional TVS is suitable for AC circuits and the unidirectional TVS is generally used for DC circuits.
TVS device's electro-vapor characteristics:
1. The VI characteristic of unidirectional TVS. The forward characteristic of unidirectional TVS is the same as that of ordinary zener diode. The reverse breakdown inflection point is approximately “right angle”, which is a hard breakdown. It is a typical PN junction avalanche device. The curve segment from the breakdown point to the Vc value indicates that when there is an instantaneous overvoltage pulse, the current of the device increases abruptly and the reverse voltage rises to the clamp voltage value and remains at this level.
2. VI characteristics of bidirectional TVS, VI characteristic curve of bidirectional TVS is like two unidirectional TVS "back-to-back" combination, it has the same avalanche breakdown characteristics and clamping characteristics in both positive and negative directions, and the breakdown voltage on both sides. The symmetry relationship is: 0.9≤V(BR)(positive)/V(BR)(reverse)≤1.1. Once the interference voltage across it exceeds the clamping voltage Vc, it will be immediately suppressed. The two-way TVS is in the AC loop. The application is very convenient.