CH1817 Overview
Referring to the block diagram in Figure 1, ining ring detection is performed by the CH1817 and the RI pin is set Low during the 2 second (typical) ring period and is restored to High for the 4 seconds (typical) between rings. During ining ring signal activity, the RI output is pulsed at the same frequency as the ringing signal, typically 20Hz. Figure 2 contains additional external circuitry which may be used to...