The TISP5070H3BJR-S is a forward-conducting unidirectional thyristor overvoltage protector designed for analogue line card and ISDN protection applications. It features an ion-implanted breakdown region that provides precise and stable voltage clamping with low voltage overshoot under surge conditions. The device has a repetitive peak off-state voltage (V_DRM) of -58 V and a breakover voltage (V_BO) of -70 V, with a breakover current of -150 to -600 mA. It is rated for 8 kV 10/700 and 200 A 5/310 ITU-T K.20/21/45 surge protection, and incorporates an anti-parallel diode that limits positive overvoltages while the thyristor crowbars negative overvoltages into a low-voltage on state. This device is ideal for protecting analogue SLIC circuits, ISDN U interfaces, and ISDN power supplies in telecommunications equipment.