Integrated Circuit

HT9170 DTMF Receiver

· Operating voltage: 2.5V~5.5V
· Minimal external components
· No external filter is required
· Low standby current (on power down mode)
· Excellent performance
· Tristate data output for mC interface
· 3.58MHz crystal or ceramic resonator
· 1633Hz can be inhibited by the INH pin
· HT9170B: 18-pin DIP package
HT9170D: 18-pin SOP package

General Description
The HT9170 series are Dual Tone Multi Fre- quency (DTMF) receivers integrated with digi- tal decoder and bandsplit filter functions. The HT9170B and HT9170D types supply power-down mode and inhibit mode operations. All types of the HT9170 series use digital count- ing techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code output.

Highly accurate switched capacitor filters are employed to divide tone (DTMF) signals into low and high group signals. A built-in dial tone rejection circuit is provided to eliminate the need for pre-filtering.