POWER CROSS DETECTION USING LOOP CURRENT AND VOLTAGE

摘要

A power cross detection circuit that detects a power cross condition on the ring and tip lines of a telephone system. The power cross detection circuit senses a loop current flowing across a ring feed resistor (Rgfd 1), as well as a loop voltage at a first node (2) and a second node (4) at opposite ends of the ring feed resistor. Based on these sensed values, a threshold voltage for detecting a power cross condition can be adjusted to detect the power cross condition at a lower voltage value.