POTS Phone Lines

Ground Referenced POTS Tip & Ring Ports

Design Notes:

Protection Application:
This note covers three types of ground referenced POTS Tip & Ring Ports. Ground referenced applications are usually associated with the CO end of the line. Most CPE protection schemes are NOT ground referenced. POTS (Plain Old Telephone Service) lines carry normal voice telephone signals. During ringing, the voltages can approach 275 volts. These solutions can also be used for most ADSL applications (up to 1.1 Mhz).
Solution Description:
Littelfuse offers a range of SIDACtor® and TeleLink or PTC solutions. Some common solutions are presented in the diagrams at the left.
Companion Solutions:
Protection can be downgraded to "B" rated devices when PTC’s or LFR’s are employed. Many devices are offered in DO-214/Compak packages. The P6002CB is a great solution when board space is critical. "A" rated devices can be used in many ITU K.20 applications.
Regulatory Issues:
This solution is designed to comply with Telcordia’s GR-1089 intra-building requirements.
Unique Features:
The P3206UC is a 2-Port solution in a unique 6-Pin package.
Application Warnings: