HT8665

The HT8665 is a single chip CMOS LSI using an ADM algorithm. It is designed for applications on talking back with an echo effect. Functions of the IC consist of recording/playing and auto power off in addition to an echo effect. The  IC starts recording when a sound input is detected, and stops to play back when silence lasts 0.5 seconds during recording. The auto power off function is activated once a REC/PLAY cycle has been implemented 64 times or an interval of silence exceeds 2 minutes.

The HT8665 provides a recording capacity of 2 seconds at a 32K bps sampling rate for DRAM of 64K (8 seconds for DRAM of 256K) and 4 seconds at a 16K bps sampling rate (16 seconds for DRAM of 256Kb). A higher sampling rate results in sounds of better quality but sacrifices the recording time, and vice versa.