A single-chip telephone line interface in BCD technology

The authors describe an integrated electronic hook switch which, in conjunction with a low-voltage monochip, makes a two-chip telephone set possible. This chip integrates all the functions of line interface provided by discrete components and/or mechanical switches and meets European standards. The device satisfies different requirements depending on the telephone function, such as ringing, conversation, and dialing. The chip presented proves that a device requirements of high voltage, high power, low leakage, and low-voltage operation can be integrated using a suitable mixed technology and nonconventional circuit techniques.<>