Description:
The NTE1690 is a low threshold voltage, field–implanted, metal gate CMOS integrated circuit in a 16–Lead DIP type package. This device interfaces directly to a standard telephone keypad and generates all dual tone multi–frequency pairs required in tone dialing systems. The tone synthesizers are locked to an on–chip reference oscillator using an inexpensive 3.579545MHz crystal for high tone accuracy. The crystal and an output load resistor are the only external components required for tone generation. A MUTE OUT logic signal, which changes state when any key is depressed is also provided.
Features:
• 3V to 10V Operation When Generating Tones
• 2V Operation of Keyscan and MUTE Logic
• Static Sensing of Key Closures or Logic Inputs
• On–Chip 3.579545MHz Crystal–Controlled Oscillator
• Output Amplitudes Proportional to Supply Voltage
• High Group Pre–Emphasis
• Low Harmonic Distortion
• Open Emitter–Follower Low–Impedance Output
• SINGLE TONE INHIBIT Pin