TVS (Transient Voltage Suppressors), transient suppression diode, also known as avalanche breakdown diode. There is one way and two way points, one-way TVS application in DC circuit, two-way TVS application in the AC circuit. As shown in the diagram, the TVS is in reverse parallel to the circuit. When the circuit is working normally, it is in the cut-off state (high resistance state), and does not affect the normal operation of the circuit. When the circuit is abnormal overvoltage and reaches its breakdown voltage (Xue Beng), quickly from the high resistance state to a low resistance state mutation, instantaneous discharge caused by abnormal overvoltage and overcurrent to the ground, while the abnormal safety level can withstand voltage clamp in circuit within the damage and thereby protect the circuit from the abnormal overvoltage. When the abnormal overvoltage is disappearing, the TVS value is restored to a high resistance state.
The volt ampere characteristic curve and related parameters of TVS are illustrated in Figure 2. The bidirectional TVS volt ampere characteristic curve has the opposite polarity between the first quadrant and the third quadrant, and the characteristic is similar, as shown in Figure 3. When TVS is back biased, TVS has two modes of work: standby (Gao Zukang) or clamp (relatively low impedance), such as Figure 2 third quadrant. In the standby state, the current flowing through the TVS is called the standby current (IR) or leakage current, and the size of the current varies with the junction temperature of TVS.
The I-V curves of TVS, by Gao Zukang (standby) to low impedance (clamp) change was started when the TVS avalanche breakdown, completely avalanche breakdown, TVS will instantly put into high voltage large current flows through the body and keep the clamp voltage PN junction is relatively low.