TLH7960

April 1987

LM3189 FM IF System

General Description

The LM3189N is a monolithic integrated circuit that provides

all the functions of a comprehensive FM IF system The

block diagram of the LM3189N includes a three stage FM IF

amplifierlimiter configuration with level detectors for each

stage a doubly balanced quadrature FM detector and an

audio amplifier that features the optional use of a muting

(squelch) circuit

The advanced circuit design of the IF system includes desir-

able deluxe features such as programmable delayed AGC

for the RF tuner an AFC drive circuit and an output signal

to drive a tuning meter andor provide stereo switching log-

ic In addition internal power supply regulators maintain a

nearly constant current drain over the voltage supply range

The LM3189N is ideal for high fidelity operation Distortion

in an LM3189N FM IF system is primarily a function of the

phase linearity characteristic of the outboard detector coil

The LM3189N has all the features of the LM3089N plus

additions

The LM3189N utilizes the 16-lead dual-in-line plastic pack-

age and can operate over the ambient temperature range of

b

Features

Y

point

Y

Low distortion 01% typ (with double-tuned coil)

Y

Single-coil tuning capability

Y

Y

Externally programmable recovered audio level

Y

Provides specific signal for control of inter-channel mut-

ing (squelch)

Y

Provides specific signal for direct drive of a tuning me-

ter

Y

On channel step for search control

Y

Provides programmable AGC voltage for RF amplifier

Y

Provides a specific circuit for flexible audio output

Y

Internal supply voltage regulators

Y

Externally programmable ON channel step width and

deviation at which muting occurs

Block Diagram

TLH7960 – 1

All resistance values are in X

(Toko No KACS K586HM or equivalent)

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A