HT9170D

Description

HT9170 DTMF receiver, SOP-18 — Holtek's tone decoder with built-in dial-tone filter.

The HT9170D is a Dual Tone Multi Frequency (DTMF) receiver integrated with digital decoder and bandsplit filter functions as well as power-down mode and inhibit mode operations. Such devices use digital counting techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code output. Highly accurate switched capacitor filters are implemented to divide tone signals into low and high group signals. A built-in dial tone rejection circuit is provided to eliminate the need for pre-filtering.