2021-07-15
Transient voltage suppression diode (Transient voltage suppression diode), also known as TVS transient suppression diode, is a surge absorption protection device made of diode avalanche breakdown principle. When used in parallel in the circuit, when both ends of the TVS tube are subjected to instantaneous high-energy impact, he can reduce its impedance at a very fast speed (nanosecond level), while absorbing large current, and the voltage between the two ends is clipped at a certain value, so as to ensure that the components behind are protected from transient high-energy impact and damage.
The TVS diode is added to the signal and power line to prevent the microprocessor or microcontroller from failing due to instantaneous pulse, such as electrostatic discharge effect, AC power surge and noise caused by switching power supply. 2 Electrostatic discharge effect can release more than 10000V, more than 60A pulse, and can last 10ms; The general TTL device, when encountered more than 30ms of 10V pulse, will lead to damage. The TVS transient suppression diode can effectively absorb pulses that can cause device damage, and can eliminate interference caused by switching between buses (Crosstalk). 3 The TVS diode is placed in the signal line and ground, which can avoid unnecessary noise impact on the data and control bus.
TVS transient suppression diode features:
1, the TVS diode added to the signal and power line, can prevent the microprocessor or MCU due to instantaneous pulse, such as electrostatic discharge effect, AC power surge and switching power supply noise caused by failure.
2, electrostatic discharge effect can release more than 10000V, more than 60A pulse, and can last 10ms; In general, TTL devices will cause damage when they encounter 10V pulses of more than 30ms. With TVS diodes, the pulse that can cause device damage can be effectively absorbed and interference caused by switching between buses can be eliminated (Crosstalk).
3, the TVS diode is placed in the signal line and ground, can avoid the data and control bus by unnecessary noise.
Second, TVS transient suppression diode characteristic curve
The circuit symbol of TVS is the same as that of ordinary voltage regulator diodes. Its forward characteristic is the same as that of ordinary diode; The reverse characteristics are typical of PN junction avalanche devices.
Under the action of transient peak pulse current, when the current flowing through TVS rises from the original reverse leakage current ID to IR, the voltage presented at the two poles rises from the rated reverse turn-off voltage VWM to the breakdown voltage VBR, TVS is broken down. With the appearance of peak pulse current, the current flowing through TVS reaches the peak pulse current IPP. The voltage at its poles is clamped below a predetermined maximum clamping voltage. Then, with the exponential attenuation of the pulse current, the voltage at the poles of TVS also continues to decline, and finally returns to the starting state. This is the whole process of TVS inhibiting possible surge pulse power and protecting electronic components.
