General Description
The HT9170B/D are Dual Tone Multi Frequency (DTMF) receivers 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.

FEATUREs
• 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 MCU 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