The TISP9110LDM is a programmable overvoltage protection device designed to protect modern dual polarity supply rail ringing SLICs (Subscriber Line Interface Circuits) against overvoltages on the telephone line. Overvoltages can be caused by lightning, a.c. power contact and induction. Four separate protection structures are used; two positive and two negative to provide optimum protection during Metallic (Differential) and Longitudinal (Common Mode) protection conditions in both polarities. Dynamic protection performance is specified under typical international surge waveforms from Telcordia GR-1089CORE, ITU-T K.44 and YD/T 950.