Thyristor

A switching semiconductor device with three or more PN junctions. The most common type consists of four alternating P-type and N-type layers and has three electrodes: anode (A), cathode (K), and gate (G). The on/off state between the anode and cathode can be controlled by the presence or absence of a small gate current. It can also perform switching operation by utilizing the characteristic that it turns off when the current flowing to the anode falls below a certain value. Because it has a wide range of peak reverse current and average forward current, it can be used for high-voltage and high-current applications compared to transistors of the same PN junction type. Applications include non-contact switches and rectifier devices, as well as motor control, lighting brightness control, and temperature control of electric kotatsu and electric furnaces. Triacs (bidirectional three-terminal thyristors) and GTOs are also types of thyristors.