Thyristor

A semiconductor switching device with three or more PN junctions. The most common type consists of four layers of alternating P-type and N-type material and has three electrodes: anode (A), cathode (K), and gate (G). The on/off control between the anode and cathode can be achieved with or without a small gate current. Additionally, it can perform switching operations by utilizing the characteristic that it turns off when the current flowing into the anode drops below a certain value. Due to its wide range between reverse leakage current and average forward current, it can be used for high-voltage and high-current applications compared to PN junction devices such as transistors. Applications include contactless switches, rectifying elements, motor control, lighting brightness adjustment, and temperature control of electric heating appliances such as electric kotatsu and furnaces. Triacs (bidirectional three-terminal thyristors) and GTOs are also types of thyristors.