Integration of a subscriber line interface circuit (SLIC) in a new 170 V smart power technology

Abstract

The presented IC performs the high-voltage functions of an electronic central office subscriber line interface without the need for any transformers or relays. The challenges of SLIC integration stem from the combination of requirements: 150 V supply, 0.2% accuracy and up to 200 nF loads, while operating in a harsh environment. A new BCD-process and circuitry that emphasizes the relative merits of the devices (e.g. buffers with DMOS outputs, n-type supply voltage switch, accuracy by polyresistors) yielded a 30 mm/sup 2/ rugged SLIC in the first design step. All transmission specifications are met without trimming.