TISP4145J1BJR-S is a symmetrical voltage-triggered bidirectional thyristor overvoltage protector designed as the tail (ground return) element of Y-configured protection circuits. The device features a repetitive peak off-state voltage (V_DRM) of ±120 V and a breakover voltage (V_BO) of ±145 V, with ion-implanted breakdown region technology providing precise and stable voltage characteristics and low voltage overshoot under surge conditions. It offers 2x current capability compared to Y upper elements, enabling both symmetrical and asymmetrical Y designs, and is rated for multiple international surge wave shapes including GR-1089-CORE (1000 A, 2/10 µs), IEC 61000-4-5 (800 A, 8/20 µs), and ITU-T standards. The device is packaged in SMB (DO-214AA) format and is commonly used in telecommunications equipment, ADSL modems, and other applications requiring coordinated overvoltage protection with precise voltage limiting and high surge current handling.