Protection Application:: This note covers three types of SLIC Ports: 1) Fixed battery, 2) variable negative battery and 3) variable positive and negative battery. In each case, the SLIC Driver lines must be protected from negative voltages in excess of the negative battery. Also, the lines must protect against positive voltages in excess of the positive battery or ground (when no positive battery is used). Variable battery technology is used to extend the loop that the SLIC Driver is capable of ringing. Most VoIP or broadband based solutions will use one of the first two options.
Solution Description:: Littelfuse offers a range of SLIC SIDACtor® and Battrax® protection solutions as well as TeleLink fuses. The most common solutions are presented in the diagrams at the left.
Companion Solutions:: Protection can be downgraded to "A" rated devices when PTC’s or LFR’s are employed. Many devices are offered in DO-214/Compak packages. The P0721CA2 is a great solution for indoor VoIP applications.
Regulatory Issues:: This solution is designed to comply with Telcordia’s GR-1089 intra-building requirements.
Unique Features:: Littelfuse provides the most robust battery-tracking SLIC surge protection in the industry.
Application Warnings:: Does not apply.

Solutions

SLIC Tip & Ring