TP5089

The TP5089 is a low threshold voltage, field-implanted, metal gate CMOS integrated circuit. TP5089 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 3.579545 MHz 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.