TLH5057

December 1991

TP5089 DTMF (TOUCH-TONE) Generator

General Description

The TP5089 is a low threshold voltage field-implanted met-

al gate CMOS integrated circuit It interfaces directly to a

standard telephone keypad and generates all dual tone mul-

ti-frequency pairs required in tone-dialing systems The tone

synthesizers are locked to an on-chip reference oscillator

using an inexpensive 3579545 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

Features

Y

35V – 10V operation when generating tones

Y

2V operation of keyscan and MUTE logic

Y

Static sensing of key closures or logic inputs

Y

On-chip 3579545 MHz crystal-controlled oscillator

Y

Output amplitudes proportional to supply voltage

Y

High group pre-emphasis

Y

Low harmonic distortion

Y

Open emitter-follower low-impedance output

Y

SINGLE TONE INHIBIT pin

Block Diagram

TLH5057 – 1

FIGURE 1

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A