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Bidirectional Trigger Diode
May 10, 2018

Bidirectional Trigger Diode (DIAC), also known as Trigger Diode, is a three layer structure with symmetrical two terminal semiconductor devices. Commonly used to trigger bidirectional thyristor, in the circuit for overvoltage protection purposes.

When the voltage U at both ends of the bidirectional trigger diode is lower than the forward voltage V (B0), the device has a high impedance state. When U>V (B0), the tube breaks through and leads into the negative resistance region. Similarly, when the U is greater than the reverse turning voltage V (BR), the tube can also enter the negative resistance region. The symmetry of the turning voltage is expressed by delta V (B). Delta V (B) =V (B0) -V (BR). The general Delta V (B) should be less than 2 volts.