TVS (Transient Voltage Suppressors) diode, namely transient voltage suppressor, also known as avalanche breakdown diode, is a single PN junction or multiple PN junction integrated device made by semiconductor process. About the selection guide of TVs transient suppression diode, some relevant knowledge points are summarized, including its working principle, characteristics and selection guide. Let's have a look at it in super detail!
1、 Operating principle of TVS Diode
TVs diodes can be divided into unidirectional and bidirectional. Unidirectional TVs diodes are generally used in DC power supply circuits, and bidirectional TVs diodes are used in voltage alternating circuits. When applied to the DC circuit, the unidirectional TVS diode is reversely connected in parallel in the circuit. When the circuit works normally, the TVS diode is in the cut-off state (high resistance state), which does not affect the normal operation of the circuit. When the circuit has abnormal overvoltage and reaches the breakdown voltage of TVS diode, the TVS Diode quickly changes from high resistance state to low resistance state, releases the instantaneous overcurrent caused by abnormal overvoltage to the ground, and clamps the abnormal overvoltage at a lower level, so as to protect the subsequent circuit from abnormal overvoltage. When the abnormal overvoltage disappears, the resistance of TVS Diode returns to high resistance state.
2、 TVS Diode Characteristics
• made of semiconductor process, with high reliability and no damage limit;
• glass passivation process, accurate on voltage;
• high transient power, low capacitance, low leakage current, and easy to control clamping voltage;
• fast response time: usually less than 1.0ps;
• excellent clamping ability and small breakdown voltage deviation;
• high voltage accuracy. In special applications, higher accuracy can be achieved through process or parameter screening;
• small size and easy installation;
• unidirectional and bidirectional units;
• at 10 / 1000 μ Under s waveform, the transient power can reach 200w-30000w or even higher
3、 TVS Diode Selection Guide
1) To determine the maximum DC or continuous operating voltage in the protected circuit, the rated standard voltage and "high end" tolerance of the circuit;
2) The rated transient power of TVs tube shall be greater than the maximum transient surge power that may occur in the circuit;
3) The cut-off voltage of TVs tube shall be greater than the maximum working voltage of the protected circuit;
4) The maximum clamping voltage of TVs tube shall be less than the damage voltage in the protected circuit of the later stage;
5) After determining the maximum clamping voltage of TVs, the peak pulse current is greater than the transient surge current;
6) For circuit protection of data interface, TVS Diode with appropriate capacitance shall also be selected. For example, when the signal frequency or transmission rate is high, TVs tubes with low capacitance series shall be selected;