Device for identifying line reversal/ringing signal of a telephone set

摘要

A device for identifying a line reversal signal and a ringing signal of a telephone set having a built-in ringing detection circuit includes a counter, a comparator and a latch connected with each other in series. The device can determine whether a signal on line is the line reversal signal or the ringing signal of the telephone set without using an installed CPU or a timer thereof, so as to save power and reduce the load of the CPU.