The HT9170 series are Dual Tone Multi Frequency (DTMF) receivers integrated with digital decoder and bandsplit filter functions. The H T 9 1 7 0 B a nd H T 9 1 7 0 D t y p es s u p p l y power-down mode and inhibit mode operations. All types of the HT9170 series use digital counting techniques to detect and decode all the 16