thyristor (general)

A semiconductor device that is capable, due to internal feedback, of assuming either of two stable states and maintaining the assumed state either with no sustained control current or voltage or at least with considerably less than that necessary to initially establish that state, and that is designed to operate as a switch for the principal or on‑state current.

NOTE 1 A thyristor is a switch that can be switched on either for only one direction of the principal current (a unidirectional thyristor) or for both directions (a bidirectional thyristor).

NOTE 2 The usual configuration is a pnpn configuration to which can be added other elements needed for additional functions.

NOTE 3 The term "thyristor" may be used for any member of the pnpn family (including devices having more than four layers) when such use does not result in ambiguity or misunderstanding. In particular, the abbreviated term "thyristor" is widely used for the reverse-blocking triode thyristor, formerly called "SCR", "semiconductor controlled rectifier", or "silicon controlled rectifier".

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