TISP4500H3BJR-S

This device is designed to limit overvoltages on the telephone line to ±500 V over the temperature range. The minimum off-state voltage of ±350 V allows a.c. power contact voltages of up to 245 V rms to occur without clipping. The combination of these two voltages gives protection for components having ratings of 500 V or above and ensures the protector is non-conducting for the ITU-T recommendations K.20/21/45 230 V rms power cross test condition (test number 2.3.1). The protector consists of a symmetrical voltage-triggered bidirectional thyristor. Overvoltages are initially clipped by breakdown clamping until the voltage rises to the breakover level, which causes the device to crowbar into a low-voltage on state. This low-voltage on state causes the current resulting from the overvoltage to be safely diverted through the device. The high crowbar holding current helps prevent d.c. latchup as the diverted current subsides.