Bidirectional trigger diode or two end communication device

Bidirectional trigger diode or two end communication device (DIAC). At the same time generation and bidirectional thyristor. Because of its simple structure, low price, so it is commonly used to trigger bidirectional thyristor. Can also be composed of overvoltage protection circuit.

Bidirectional trigger diode structure, symbols and the equivalent circuit shown in figure 1. Two terminal semiconductor device which belongs to the three layer structure, with high symmetry. Can be equivalent to the base open, launch the NPNtransistor electrode and the collector symmetry. The positive, reverse I-V characteristics are completely symmetrical. See figure 2. When the device at both ends of the voltage V less than the forward breakover voltage Vbo, is in a high impedance state. When v>Vbo enters the negative resistance region. Similarly,when the V exceeds the reverse snapback voltage VBR, tube can also enter thenegative resistance region. The symmetry of the breakover voltage is expressed bydelta Vb=vbo-vbr Delta Vb. General requirements vb<2V. The withstand voltagebidirectional trigger diode (Vbo) is classified into 3 grades: 20 ~ 60V.100 ~ 150V,200 ~ 250V.