This document describes the series of specific protection devices developed by STMicroelectronics for ISDN applications
This document discusses the critical importance of minimizing parasitic capacitance and capacitance imbalance in ISDN line interfaces to ensure correct signal transmission. It highlights that common-mode protection often introduces unequal capacitance between lines and earth, which can degrade signal performance.
STMicroelectronics presents its "TRIBALANCED PROTECTION" TPIxx series as a solution specifically designed for ISDN applications. The note details the conditions under which this protection is mandatory, such as when bias voltages on lines A and B differ. It outlines the available product range, offering both discrete solutions (SMTHDTxx, TPUxx) and monolithic devices (TPIxx) in various packages to balance cost and performance requirements.
| Capacitance Imbalance | 30pF |
|---|
It is mandatory when the bias voltage on line A and line B is different and the protection is realized in common mode.
The conditions are low capacitance from line to ground to avoid signal attenuation and good capacitance balance between line A and line B for good longitudinal balance.