Monolithic integrated protection circuit - has extra stage switched to output stage to increase dynamic internal impedance

摘要

The monolithic integrated protection circuit, for integrated voice circuits and AF dialling oscillators in telephony, has an extra stage (ZS) switched to the output stage (ES) between the two wires (a, b) to increase the dynamic internal impedance of the parallel voltage regulator (SPR) acting as current sink. The output stage is connected to the output (A) of a differential amplifier (T1-T4). This output is also coupled via a capacitor (C) to one of the wires (b) and to a circuit (ASH) that accelerates the charging of the capacitor. This circuit is controlled by the divided (R4-R6) voltage appearing across the two wires.