TVS diode, also known as transient voltage suppressor or avalanche breakdown diode, is a device used to protect circuits from transient overvoltage surges. During the selection process, it is important to pay attention to the following aspects:

Firstly, it is necessary to clarify the maximum DC value, rated standard voltage value, and "high-end" tolerance value of the protected circuit. These parameters are the basis for selecting TVS diodes, ensuring that the selected devices can withstand the maximum operating voltage and potential transient surge voltages in the circuit.

Secondly, the maximum clamping voltage (Vc) of the TVS diode should be less than the damage voltage of the protected circuit. Clamping voltage refers to the maximum voltage value that can be reached at both ends of a TVS under the action of peak pulse current. This parameter is crucial for protecting the components in the circuit from damage caused by high voltage. Therefore, when selecting, it is necessary to carefully check the relationship between the clamping voltage of TVS and the damage voltage of the protected circuit.

At the same time, the rated reverse turn off voltage (VRMM) of the TVS diode should be greater than or equal to the maximum operating voltage of the protected circuit. VRWM is the voltage value at both ends of a TVS diode when it operates in reverse at a specified current. At this voltage, the power consumption of the TVS diode is very small, and when using it, it should be ensured that the VRMM is not lower than the normal operating voltage of the protected circuit.

In addition, after determining the maximum clamping voltage of the TVS diode, its peak pulse current (IPP) should be greater than the transient surge current. The product of IPP and the maximum clamping voltage Vc determines the maximum transient pulse power of TVS. This parameter is very important for measuring the protection capability of TVS. Therefore, when selecting, it is necessary to ensure that the peak pulse current of the selected TVS can meet the transient surge current requirements in the circuit.

In addition to the above key parameters, it is also necessary to consider the impact of temperature changes on the characteristics of TVS diodes. The operating temperature range of TVS diodes is usually between -55 ° C and 150 ° C. When the temperature is relatively high in the circuit, it is necessary to apply derating to ensure the stability and reliability of TVS.

In addition, it is also very important to choose the appropriate type of TVS diode according to the different types of circuits. DC protection circuits mostly choose unidirectional TVS tubes, while AC protection circuits mostly choose bidirectional TVS tubes. For multi-channel protection circuits, TVS array devices can be selected; For high-power protection circuits, dedicated protection modules should be selected.

When using TVS diodes, their discreteness also needs to be considered. In order to reduce the impact of discreteness on circuit performance, the number of TVS series/parallel connections should be minimized as much as possible.