What is the principle of a TVS diode and what does it do?

What is the principle of a TVS diode and what does it do?

1. The role of transient suppression diodes

To put it in layman's terms, if the voltage impulse that the circuit can withstand is not higher than DC24V, then a 26V TVS diode is welded at the power supply, when the power supply voltage does not exceed 26V, the TVS diode is in a high-impedance state, and when the power supply instantly comes to a pulse higher than 26V, the TVS diode can quickly clamp the circuit voltage at 24V, thus ensuring the safety of the circuit board.

In general, TVS diode are used to:

1. The TVS diode is added to the signal and power line to prevent the failure of the microprocessor or microcontroller due to instantaneous fat rush, such as electrostatic discharge effect, AC power surge and switching power supply noise.

2. The electrostatic discharge effect can release pulses of more than 10000V and more than 60A, and can last for 10ms, while general TTL devices will be damaged when they encounter 10V pulses of more than 30ms. With a TVS diode, pulses that can cause damage to the device can be effectively absorbed, and interference caused by switching between buses can be eliminated (Crosstalk).

3. Place the TVS diode between the signal line and the ground to avoid unnecessary noise affecting the data and control bus.

2. What is a TVS diode?

Transient Voltage Suppressor (Transient Voltage Suppressor) is referred to as TVS diode, and the electrical characteristics of TVS diode are determined by the P-N junction area, doping concentration and wafer resistance. Its ability to withstand surge currents is proportional to its P-N junction area. TVS is widely used in the protection of semiconductors and sensitive devices, and is usually used for the protection of secondary power supplies and signal circuits, as well as anti-static. It is characterized by fast response speed (PS level), small size, large pulse power, low clamping voltage, etc. Its 10/1000μs wave pulse power is from 400W~30KW, pulse peak current from 0.52A~544A, and breakdown voltage is from 6.8V~550V, which is convenient for the use of various circuits with different voltages.

3. The working principle of the TVS diode

The device is connected in parallel in the circuit, when the circuit is working normally, it is in the cut-off state (high impedance state), which does not affect the normal operation of the circuit, when the circuit has abnormal overvoltage and reaches its breakdown voltage, it quickly changes from the high impedance state to the low impedance state, provides a low impedance conduction path for the instantaneous current, and at the same time clamps the abnormal high voltage within a safe level, so as to protect the protected IC or line; when the abnormal overvoltage disappears, it returns to the high impedance state, and the circuit works normally.