The TISP4240M3BJR-S is a Bidirectional Thyristor, overvoltage protector series, designed to limit overvoltage on telephone line. Overvoltage is normally caused by AC power system or lightning flash disturbances which are induced or conducted on to telephone line. A single device provides 2-point protection and typically used for protection of 2-wire telecommunication equipment (e.g. between ring and tip wires for telephones/modems). Combinations of devices can be used for multi-point protection (e.g. 3-point protection between ring/tip/ground). The protector consists of a symmetrical voltage-triggered bidirectional thyristor. Overvoltage is initially clipped by breakdown clamping until voltage rises to break over level, which causes device to crowbar into a low-voltage on state. This low-voltage on state causes current resulting from overvoltage to be safely diverted through the device. The high crowbar holding current helps to prevent DC latchup as diverted current subsides.
