Bourns Dual Polarity SLIC Surge Protector
Bourns dual polarity SLIC surge protector is a programmable over-voltage protection device designed to protect modern dual polarity supply rail ringing SLICs (Subscriber Line Interface Circuits) against over-voltages on the telephone line. Over-voltages 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-1089-CORE, ITU-T K.44 and YD/T 950. The Model TISP9110MDM is programmed by connecting the G1 and G2 gate terminals to the negative (-V(BAT)) and positive (+V(BAT)) SLIC Battery supplies respectively. This creates a protector operating at typically +1.4V above +V(BAT) and -1.4V below -V(BAT) under a.c. power induction and power contact conditions. The protector gate circuitry incorporates 4 separate buffer transistors designed to provide independent control for each protection element. The gate buffer transistors minimize supply regulation issues by reducing the gate current drawn to around 5mA, while the high voltage base emitter structures eliminate the need for expensive reverse bias protection gate diodes. Bourns dual polarity SLIC surge protector is rated for common surges contained in regulatory requirements such as ITU-T K.20, K.45, Telcordia GR-1089- CORE, YD/T 950. With the use of appropriate over-current protection devices such as the Bourns Multifuse and Telefuse devices, circuits can be designed to comply with modern telecom standards.