Light activated triacs and high voltage thyristors

Trigger power amplification and different methods to avoid or compensate fault triggering enable the design of light activated power thyristors and auxiliary thyristors which can be triggered with light power in the mW range. Commutating dv/dt of bidirectional thyristors and turn-off time of trigger sensitive thyristors can be kept in a reasonable range. The degradation rate of Si-doped GaAs LEDs is low enough to enable compact opto-coupler-type power devices when the trigger current is kept below 100 mA.