How do TVS diodes protect circuits?

TVS diodes are widely used in power supply circuits, TVS diodes are small in size, fast in response time, absorb inrush current and voltage at the speed of microseconds, and protect electrical equipment.

TVS diode and Zener diodes work on the same principle, but they have certain structural differences. One of the big differences is that the PN junction area of the Zener diode is relatively small, and the reverse current that can be withstood is also very small.

The maximum reverse current of the low-power regulator diode (power between 0.5~1W) is tens of mA to hundreds of mA; The PN junction area of the TVS transient suppression diode is relatively large, and the power dissipated is also large, and the maximum reverse current can be up to several amperese to tens of amperes. Therefore, it can absorb the instantaneous high current caused by instantaneous high-voltage pulses. Generally, the power of the regulator diode is 0.5~3W, while the power of the transient diode can reach 300W to 1500W, and some can reach more than 10kW for high voltage. 

For example, ESD-TVS diode is a transient diode with a reverse breakdown voltage of 6.4~7.3V and a power dissipation of 500w, and the maximum pulse current Ipp that it can withstand is 52~54A. 

Transient diodes TVS diode are used as protection circuits, which are connected in parallel to the protection circuits. It does not require a current-limiting resistor R. If the working voltage of the protected circuit is +4V, a diode with 5.5~6V breakdown can be selected. In normal operation, the transient diode does not work and is quite open; When there is a transient high-voltage pulse in the operating voltage, the transient suppression diode is clamped at about 8V when the high-voltage pulse is acted, and the 8V voltage is safe for the circuit operating at 4V. When the high-voltage pulse has passed, the transient diode is quite open.