Controlled switching mechanism for accomplishing soft polarity reversal, ring-trip filtering, and line voltage measurements in a subscriber line interface circuit using common capacitor

摘要

A controllably switched arrangement selectively couples multiple circuit functions, such as reverse polarity detection, ring-trip and line voltage measurement, of a telecommunication card to the same external programming component (e.g., capacitor) on an as needed basis, by means of associated coupling circuits and a controlled switching circuit. The coupling circuits are controllably enabled/disabled in association with the particular circuit function required, while the controlled switching circuit selectively connects each coupling circuit with the external component. Through combined control of the coupling circuits and the switching circuit, respectively different circuit functions can be implemented with the same external component.