The difference between TVS transient suppression diode and voltage regulator diode
A voltage regulator diode is a semiconductor device that has high resistance until the critical reverse breakdown voltage. At this critical breakdown point, the reverse resistance decreases to a very small value, and in this low resistance region, the current increases while the voltage remains constant. Zener diodes are classified based on their breakdown voltage, and because of this characteristic, Zener diodes are mainly used as voltage regulators or voltage reference components. Zener diodes can be connected in series for use at higher voltages, and more stable voltage can be obtained through series connection.
TVS (Transient Voltage Suppressor) is a widely used new type of high-efficiency circuit protection device, which has extremely fast response time (sub nanosecond level) and considerable surge absorption capability. When its two ends are subjected to an instantaneous high-energy impact, TVS can quickly change the impedance value between the two ends from high impedance to low impedance, absorbing a momentary high current, thereby clamping the voltage at both ends to a predetermined value, and protecting the subsequent circuit components from the impact of transient high voltage spikes. Therefore, TVS can be used to protect devices or circuits from static electricity, transient voltages generated during inductive load switching, and overvoltage caused by induced lightning.
TVS tubes, like voltage regulators, are also used in reverse. VR is referred to as the maximum transition voltage, which is the critical voltage before reverse breakdown. VB is the breakdown voltage, and its corresponding reverse current IT is generally 1mA. VC is the maximum clamping voltage, and when the peak current flowing through the TVS tube is the high current of IPP, the voltage at both ends of the tube no longer rises. Therefore, TVS tubes can always limit the port voltage of protected devices or equipment within the effective range of VB-VC. Unlike voltage regulators, the value of IPP can reach several hundred amperes, while the clamping response time is only 1 × 10-12s. The maximum allowable pulse power of TVS is PM=VC * IPP, and under a given maximum clamping voltage, the greater the power consumption PM, the greater its ability to withstand surge currents.
The similarities and differences between voltage regulators and TVS transistors. In the application of electronic systems, transient interference of voltage and current often causes damage to electronic equipment. The significant feature of transient interference is that it has a very short duration of action, but high voltage amplitude and large transient energy, so it is very destructive. In order to prevent such damage, TVS tubes have been widely used. TVS (Transient Voltage Suppressor) is a high-performance circuit protection device developed on the basis of the voltage regulator process. Its circuit symbol is the same as that of a regular voltage regulator diode, and its appearance is no different from that of a regular diode. When the two ends of the TVS tube are subjected to instantaneous high-energy impact, it can rapidly reduce its impedance (up to 1 * 10-12 seconds), absorb a large current, clamp the voltage between its two ends at a predetermined value, and ensure that subsequent circuit components are not damaged by transient high-energy impact. We often see TVS diodes as one of the main means of ESD protection in some precision electronic devices.
As a commonality between the two, they can both be used for voltage stabilization and operate in reverse cut-off state. Their forward characteristics are the same as ordinary diodes, and their reverse characteristics are typical PN junction avalanche devices. However, the breakdown current of TVS diodes is smaller, with only 1mA of voltage regulation for voltages greater than 10V. In comparison, the breakdown current of Zener diodes is much larger, but the precision of Zener diode voltage regulation can be relatively high. Moreover, TVS transistor emphasizes transient response, so its time parameter is very important, which means that the response time of the voltage regulator diode is usually slower than that of TVS transistor. At the same time, the power of TVS tube is relatively high, while the power of voltage regulator tube is relatively low. Secondly, conceptually speaking, TVS tubes are mainly used to prevent the influence of momentary high voltage and ultimately achieve the purpose of voltage stabilization, which is different from the role of voltage regulators.