Transient Voltage Suppression Diode

Introduction of Transient Voltage Suppression Diode

Transient Voltage Suppressor abbreviation TVS ，It is a high-efficiency protective device in the form of diode. When the two poles of TVS diode are impacted by the reverse transient high energy, it can change the high impedance between the two poles into low impedance at the speed of 10 to the negative 12th power second, absorb the surge power of several kilowatts, make the voltage clamp between the two poles at a predetermined value, effectively protect the precision components in the electronic circuit from the damage of various surge pulses.  Due to its advantages of fast response time, large transient power, low leakage current, easy control of clamping voltage, no damage limit, small size, etc., it has been widely used in computer systems, communication equipment, AC/DC power supply, common mode/differential mode protection, RF coupling/IC drive receiving protection, motor electromagnetic interference suppression, audio/video input, sensor/transmission, industrial control circuit, relay The suppression of contactor noise and other fields.

TVS diodes can be divided into unidirectional and non-bidirectional ones. The characteristics of unidirectional TVS tubes are similar to that of non-regulated diodes. The characteristics of bidirectional TVS tubes are equivalent to that of two regulated diodes in reverse series. The main characteristic parameters are:

(1) Reverse off-state voltage (cut-off voltage) VRWM without reverse leakage current IR:

The reverse off state voltage (cut-off voltage) VRWM represents the highest working voltage when the TVS diode is on, and there is only a small reverse leakage current IR at this voltage.

(2) Breakdown voltage VBR: the voltage when TVS diode passes the specified test current IT, which is the mark voltage indicating that TVS tube is on.

(3) Pulse peak current IPPM: 10/1000 allowed by TVS diode μ Maximum peak current of s wave (8/20 μ The peak current of s wave is about 5 times that of s wave), which may cause permanent damage. In the same series, the higher the breakdown voltage, the smaller the peak current allowed to pass through the tube.

(4) Maximum clamping voltage VC: the voltage at both ends when TVS diode flows through the pulse peak current IPPM.

(5) Pulse peak power PPPM: Pulse peak power refers to 10/1000 PPPM μ The pulse peak current IPPM of s wave is not the product of the maximum clamping voltage VC, i.e. PPPM=IPPM * VC.

(6) Steady state power PD: TVS diode can also be used as zener diode. At this time, steady state power should be used.

(7) Inter-pole capacitance CPP: TVS diode has a larger inter-pole capacitance CPP, and the greater the power, the greater the capacitance. The selection of TVS must be determined according to the specific conditions of the circuit. Generally, there are the following principles:

(1) The maximum clamping voltage shall not be greater than the maximum allowable voltage of the circuit;

(2) The clamping voltage shall not be lower than the maximum working voltage of the circuit;

(3) The maximum allowable pulse power measured under the standard pulse duration of 10-1000us must be greater than the peak pulse power in the circuit.