SANYO LA1231N Datasheet

LA1231N

Ordering number : EN660A

FM IF System

Monolithic Linear IC

SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN

O2097HA (KT)/8044/D040KI No.660-1/8

Package Dimensions

unit: mm

3006B-DIP16

[LA1231N]

SANYO: DIP16

quadrature detecting circuit is attached with a low frequency preamplifier and muting control circuit.
The muting drive stage is composed of the following 3 circuits.

1) A level detection circuit which detects the S/N ratio of carrier wave when the input is weak.

2) A circuit which detects the dc output of FM detector's 'S' curve when detuning is made.

3) A driving circuit.
Thus, this muting driving stage can reduce foreign factors such as the interstation noises, the shock noise caused from
muting when detuning is made, and so forth.
Besides, a voltage-inverting circuit is built in LA1231N so that the muting may be enabled at any appropriate input signal
level. The output of this voltage-inverting circuit is connected with the muting drive output terminal. Thus, the muting can
be placed to the ON or OFF status when a control voltage is applied from other section to the input terminal of the voltage­inverting circuit. For the control voltage, the output of the signal meter driver is appropriate. Both the AFC output stage
and tuning meter driving stage are of the current-driven type. So, not only the sensitivity of AGC but also the muting band
(when detuning is made) can be controlled by an outer resistor.
Being utilized for disabling the FM IF amplifier when AM reception is made, the IF amplification/stop circuit can decrease
the shock noise caused at the conversion between FM and AM reception modes.

Functions

• IF amplification, Limiter. • Quadrature detection.

• AF preamplifier. • Muting at weak.

• Muting at the detuning. • Signal meter drive output.

• AFC tuning meter drive output. • Delay AGC output.

• Inverting circuit for muting drive voltage. • IF amplifier stop circuit.

Overview

Being developed for FM IF System, LA1231 is a highly
integrated circuit in which almost all functions are
contained concerning the FM tuner IF stage. The block
diagram of equivalent circuit is shown below. Usual
peripheral circuits are shown also in examples of
application circuits.
The IF amplifier and limiter stages are composed of 6­stage double-end type differential amplifier, which is
superior on its AMR. The signal meter driving stage which
is located in parallel therewith consists of a 3-stage level
detector circuit and a drive circuit in order to extend the
linear area.
The FM detection stage composed of a double-balance type

LA1231N

No.660-2/8

Specifications
Maximum Ratings

at Ta=25°C

Parameter Symbol Conditions Ratings Unit

Maximum supply voltage V

CC

max Pin 11 16 V

Maximum input voltage V

IN

Pins 1-2 ±1 Vp-p

Maximum supply current I

CC

Pin 11 40 mA

Maximum flow-in current I

15

Pin 15 1 mA

I

16

Pin 16 1 mA

Maximum flow-out current I

10

Pin 10 2 mA

I

12

Pin 12 2 mA

I

13

Pin 13 2 mA

I

15

Pin 15 2 mA
Allowable power dissipation Pd max 650 mA
Operating temperature Topr –20 to +70 °C
Storage temperature Tstg –40 to +125 °C

Voltage regulator

IF amp/limiter

Guadrature

limiter

AFC/tuning
meter drive

Guadrature

det

Level

det

IF amp

stop

Signal meter

drive

Mute drive

Level

det

Level

det

Level

det

Level

det

DC

level

AF amp

Mute

control

Features

• High sensitivity on limiting : 18µV typ.

• Low distortion : 0.05% typ. determined by the linearity of phase characteristics in phase shifting circuit.

• High demodulation output : 330 mVrms typ.

• High S/N ratio : 78.5dB typ.

• Muting at detuning with little shock noise.

• Single meter drive output proportional with the input signal level dB.

• Detuning muting band having good symmetrics.

• Tuning meter driving output having wide swing width.

• Delay AGC drive output for front end.

• Constant voltage circuit is built-in : operation voltage=9 to 14V.

• Muting characteristics between adjacent stations are distinguished.

Equivalent Circuit Block Diagram

LA1231N

No.660-3/8

Recommended Operating Conditions at Ta=25°C

Parameter Symbol Conditions Ratings Unit

Supply voltage V

CC

12 V

Operating Characteristics at Ta=25°C, V

CC

=12V, f=10.7MHz

Parameter Symbol Conditions

Ratings

min typ max

Unit

Quiescent current I

CCO

22 30 mA

Current drain I

CC

VIN=100dBµ 26.5 33 mA

Demodulated output Vo V

IN

=100dBµ, 400Hz-100% mod 240 330 460 mVrms

S/N V

IN

=100dBµ, 400Hz-100% mod 72 78.5 dB

Input limiting voltage V

IN(lim)

Vo 3dB down, 400Hz-100% mod 25 31 dBµ

Total harmonic distortion THD V

IN

=100dBµ, 400Hz-100% mod 0.05 0.3 %

Muting sensitivity V

IN(mute)V12

=1.4V 23 29 35 dBµ

Muting attenuation Mute(att) V

5

=2V, VIN=100dBµ, 60 65 dB

400Hz-100% mod

Muting bandwidth BW(mute) V

IN

=100dBµ, V12=1.4V 140 220 370 kHz

AM rejection ratio AMR V

IN

=100dBµ, FM : 400Hz-100% mod 45 60 dB

AM : 1kHz-30% mod

Muting driving output V

12

Quiescent 4.0 4.9 6.0 V
V

IN

=100dBµ 0 0 0.3 V

Signal meter driving output V

13

Quiescent 0 0 0.1 V
V

IN

=70dBµ 1.9 3.0 4.2 V

V

IN

=100dBµ 4.5 5.5 V

AGC output V

15

Quiescent 4.2 5.0 5.5 V
V

IN

=100dBµ 0 0 0.5 V

IF off current I

15(off)

Quiescent, V

8-10

≤20mV 10 35 60 µA

Voltage of muting operation V

16

(mute) VIN=100dBµ, V12=1.4V 0.7 0.84 1.0 V

Offset voltage V

6-10 B

Quiescent, pin 6-10 –0.5 0 +0.5 V

V

7-10 B

Quiescent, pin 7-10, R

7-10

=5.1kΩ –0.25 0 +0.25 V

Pin voltage V

1

Quiescent 2.6 V

V

2

Quiescent 2.6 V

V

3

Quiescent 2.6 V

V

6

Quiescent 5.6 V

V

7

Quiescent 5.6 V

V

8

Quiescent 5.4 V

V

10

Quiescent 5.6 V

V

12

Quiescent 4.9 V

V

13

Quiescent 0 V

V

15

Quiescent 5.0 V