Transient Voltage Suppressor (TVS) is a special type of diode that works mainly based on the avalanche breakdown effect of PN junction. The following is a detailed introduction to its working principle:

1、 Avalanche breakdown effect

The avalanche breakdown effect is the core principle of TVS diode operation. In a PN junction, when the applied voltage exceeds its breakdown voltage, the electrons and holes in the PN junction accelerate under the action of an electric field, collide with lattice atoms, and produce more electron hole pairs. These newly generated electron hole pairs continue to accelerate in the electric field, forming a chain reaction that leads to a sharp increase in current in the PN junction, resulting in avalanche breakdown

2、 The working principle of TVS diode

Normal state:

When the voltage across the TVS diode is lower than its breakdown voltage, the TVS diode is in a high impedance state and can be considered non-conductive. At this point, the current from the power supply flows into the internal working circuit without passing through the TVS diode

Avalanche breakdown state:

When the voltage across the TVS diode exceeds its breakdown voltage, the PN junction quickly enters an avalanche breakdown state, forming a low impedance path. At this point, the TVS diode quickly conducts the transient voltage to ground, thereby protecting the electronic device from voltage transient surges

Recovery status:

After the transient voltage disappears, the PN junction of the TVS diode returns from the avalanche breakdown state to the normal state, and its impedance changes again to the high impedance state, waiting for the next transient voltage surge

3、 Characteristic parameters of TVS diode

Breakdown voltage: An important parameter of TVS diodes that determines the voltage at which the diode begins to conduct. The lower the breakdown voltage, the faster the response speed of the diode to voltage transient shocks, but it may also cause the diode to malfunction at normal operating voltage

Breakdown current: The current of a PN junction in an avalanche breakdown state, which is related to the applied voltage, doping concentration, and structure of the PN junction. The breakdown current of TVS diodes is usually between tens of amperes and several thousand amperes

Recovery time: The time required for a PN junction to recover from avalanche breakdown state to normal state. The recovery time of TVS diodes is usually in the nanosecond range, which enables them to quickly respond to transient voltage surges

4、 Application of TVS diodes

TVS diodes are commonly used to protect unipolar power and signal lines from damage caused by overvoltage. Bidirectional TVS diodes have breakdown characteristics in both directions, making them commonly used to protect bipolar power supplies and differential signal lines. In addition, an array TVS composed of multiple TVS components can provide higher power capacity and smaller capacitance, making it suitable for protecting high-speed signal lines

In summary, TVS diodes quickly respond to transient voltage surges by utilizing the avalanche breakdown effect of PN junctions and conduct overvoltage to ground, thereby protecting electronic devices from damage. Its unique characteristics and wide range of applications make it one of the indispensable components in the field of electronics