37951

·HIGHLY INTEGRATED SUBSCRIBER LINE INTERFACE KIT FOR PABX AND KEY SYSTEM APPLICATIONS
·IMPLEMENTS ALL KEY ELEMENTS OF THE BORSCHT FUNCTION
·INTEGRATED ZERO CROSSING BALANCED RINGING INJECTION ELIMINATES EXTERNAL RELAY AND CENTRALISED RINGING GENERATOR
·ZERO NOISE INJECTED ON ADJACENT LINES DURING RINGING SEQUENCE LOW POWER IN STANDBY AND ACTIVE MODES
·BATTERY FEED WITH PROGRAMMABLE LIMITING CURRENT
·PARALLEL LATCHED DIGITAL INTERFACE SIGNALLING FUNCTIONS (OFF HOOK, GND-KEY)
·LOW NUMBER OF EXTERNAL COMPONENTS
·INTEGRATED THERMAL PROTECTION
·INTEGRATED OVER CURRENT PROTECTION
·0°C TO 70°C: L3234/L3235N
·-40°C TO 85°C: L3234T/L3235NT

The 37951 is a highly integrated SLIC KIT targeted to PABX and key system applications The kit integrates the majority of functions required to interface a telephone line. The 37951 implements the main features of the broths function:
- Battery Feed (Balanced Mode)
- Ringing Injection
- Signalling Detection
- Hybrid Function
The Kit comprises 2 devices, the 37951ringing injector fabricated in Bipolar in 140V Technology. Its function is to amplify and inject in balanced mode with zero crossing the ringing signal. The 37951 requires an external positive supply of 100V and a low level sinusoid of approx. 950mVrms. The L3235N Line Feeder is integrated in 60V Bipolar Technology. The L3235N provides battery feed to the line with programmable current limitation. The two to four wire voice frequency signal conversion is implemented by the L3235N and line terminating and balance impedances are externally programmable. The L3234/L3235N kit is designed for low power dissipation. In a short loop condition the extra power is dissipated on an external transistor. The Kit is controlled by five wire parallel bus and interfaces easily to all the STLC5046 and STLC5048 CODECs. In Kit with STLC5048 (see fig 1) the line impedance synthesis and echo canceling are performed inside the CODEC.