light triggered thyristor

Light controlled thyristor, also known as GK type optical switch transistor, is a type of photosensitive device.

1. Structure of Light Controlled Thyristor

Typically, thyristors have three electrodes: control electrode G, anode A, and cathode C. However, since the control signal of the light controlled thyristor comes from the irradiation of light, there is no need to lead out the control electrode, so there are only two electrodes (anode A and cathode C). But its structure is the same as ordinary thyristors, consisting of four layers of PNPN devices.

2. Characteristics of Light Controlled Thyristors

In order for the light controlled thyristor to trigger conduction under weak light illumination, it is necessary to ensure that the light controlled thyristor can reliably conduct under extremely small control currents. In this way, the light controlled thyristor is limited by high temperature and voltage resistance, and under current conditions, it is impossible to make high-power thyristors like ordinary thyristors.

Light controlled thyristors have similar characteristics to ordinary thyristors, except for different triggering signals. Therefore, when using them, they can be selected according to the characteristics of ordinary thyristors, as long as they are light controlled. Light controlled thyristors have certain requirements for the wavelength of the light source, namely selectivity. Infrared light with a wavelength of 0.8-0.9um and laser light with a wavelength of around 1um are ideal light sources for photo controlled thyristors.