TLH5201

December 1989

TP5700A

Telephone Speech Circuit

General Description

The TP5700A is a linear bipolar device which includes all

the functions required to build the speech circuit of a tele-

phone It replaces the hybrid transformer compensation cir-

cuit and sidetone network used in traditional designs When

used with an electret microphone (with integral FET buffer)

and dynamic receiver superior audio linearity distortion and

noise performance are obtained Loop attenuation compen-

sation is also included

The low voltage design enables the circuit to work over a

wide range of operating conditions including long loops ex-

tension telephones and subscriber carrier applications

Operating power is derived from the telephone line

Features

Y

5 mA – 120 mA loop operation

Y

Voltage swing down to 10V

Y

Electret microphone amplifier

Y

Receive amplifier with push-pull outputs

Y

Automatic gain compensation for loop length

Y

Sidetone impedance independent of input impedance

Y

DTMF interface with muting

Y

Voltage regulator outputs for DTMF generator etc

Y

Works in parallel with a standard phone on 20 mA loop

Y

Available in small outline surface mount package

Simplified Block Diagram

TLH5201 – 1

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A