TVS knowledge sharing

More and more people are raising awareness of safety first. More than ten years have devoted themselves to research, development, and production of patch transistors. How do manufacturers view the importance of TVS tubes? Recently, Yongyutai has promoted a full range of patch-type TVS tubes and has caused new demands. Businessmen are hot.

Let's review together: transient over-voltage, these dangerous surge energy can not be drained or absorbed in the circuit, and invade the internal circuit of electrical equipment, can affect the normal operation of electronic equipment, and even burn the circuit; and integrated digital circuit It is susceptible to surge voltage such as ESD/EFT (Electrostatic Discharge/Electrical Fast Transient Burst), which may cause abnormal operation, crash, or even damage and cause other safety problems. The use of TVS devices for fine protection of circuits can effectively protect precision components in electronic circuits from various surge pulses.

First, the definition of transient voltage suppression diode called TVS (TRANSIENT VOLTAGE SUPPRESSOR), is a new product developed on the basis of the voltage regulator process, the circuit symbol is the same as the ordinary zener diode, and the appearance is also the same as the ordinary diode. When the TVS tube is subjected to momentary high energy shocks at both ends, the TVS reacts faster than the RC loop, causing a sudden drop in impedance while absorbing a large current and clamping the voltage between the two ends to a predetermined value. This ensures that the precision components in the rear electronics are protected from transient high-energy shocks.

Second, the category of TVS devices can be divided into two kinds according to polarity, unipolar and bipolar, and can be divided into general-purpose devices suitable for various circuits and special-purpose devices applicable to special circuits according to applications. A one-way TVS that suppresses the reversal, and a two-way TVS that has an exchange. (Yeonyutai Chipset will use A to indicate one-way, and CA indicates to use two-way.)

Third, the application of TVS tube because of its fast response time, large transient power, low capacitance, low leakage current, small breakdown voltage deviation, clamping voltage is easier to control, no damage limit, small size, easy to install, etc. Widely used in security, communications, automotive electronics, home appliances, digital, computers, wireless remote control, intelligent lighting and other fields.

IV. Selection Techniques for TVS Transient Voltage Suppression Diodes: Determine the maximum DC or continuous operating voltage of the circuit being protected, the nominal voltage of the circuit, and the "high end" tolerance. The TVS rated reverse turn-off VWM should be greater than or equal to the maximum operating voltage of the circuit being protected. If the selected VWM is too low, the device may enter an avalanche or the reverse leakage current will affect the normal operation of the circuit. The voltage is connected in series and the current is divided in parallel. The maximum clamp voltage VCS of the TVS should be less than the damage voltage of the circuit to be protected. For the specified pulse duration, the TVS maximum peak pulse power consumption PM must be greater than the peak pulse power that may be present in the protected circuit. After determining the maximum clamp voltage, the peak pulse current should be greater than the transient surge current. For the protection of the data interface circuit, care must also be taken to select a TVS device with a suitable capacitance C. Select TVS polarity and package structure according to the application. It is more reasonable to choose bipolar TVS for the alternating current circuit; It is more advantageous to choose TVS array for multiline protection. Temperature considerations. Transient voltage suppressors can operate between -50 and +150°C. If TVS is required to operate at a varying temperature, its reverse leakage current ID increases with increasing; power consumption decreases with increasing TVS junction temperature, from +25°C to +175°C, approximately a 50% drop in rain The breakdown voltage VBR increases with temperature by a certain factor. Therefore, you must consult the relevant product data and consider the effect of temperature changes on its characteristics.