SANYO LA1235 Datasheet

LA1235

Ordering number : EN873F

FM IF System Applications

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)/63095HA (KOTO) /O076AT/8044KI, TS/4241KI/3091KI No.873-1/12

Overview

The LA1235 is a high integrated IC developed for use in
high S/N, low distortion FM IF system applications. This
IC features S/N=88dB, distortion factor=0.015% and has
almost all functions required for FM tuner IF stage.
The IF amplifier and limiter stage consist of 6 stages of
double ended differential amplifier having an excellent
AMR, and this stage is followd by the signal meter driver
which consists of 4 stages of level detector, thereby
creating extended linearity up to strong input. The FM
detector stage consists of a double balanced quadrature
detector to which a low frequency preamplifire and a
muting controller are attached. The muting drive stage
consists of an OR circuit for weak signal muting drive
output which detects signal intensity and detuning muting
drive output which detects S curve DC output and enables
the prevention of noise at the time of weak signal and
detuning. Further, the weak signal muting drive output
circuit contains a Schmitt circuit having hysteresis and
enables the prevention of muting malfunction due to
amplitude component at the time of weak signal. The AFC
output and tuning meter drive stage is of current drive type
which makes it possible to adjust AFC sensitivity and
muting band width by means of an external resistor, and
the built-in tuning meter null (short) circuit foreces the
tuning meter to be [0] when th IF amplifier stops working.
The IF amplifier stop circuit, being a circuit to stop the FM
IF amlifier at the time of AM reception, makes it possible
to decrease shock noise due to FM-AM receiving mode
switchover.

Package Dimensions

unit: mm

3006B-DIP16

[LA1235]

SANYO: DIP16

Functions

• IF amplifier, Limiter.

• Quadrature detection.

• AF preamplifier.

• Signal intesity muting drive output.

• Detuning muting drive output.

• AF signal muting circuit.

• Signal meter drive output.

• AFC, tuning meter drive output.

• IF amplifier stop circuit.

• Tunig meter null circuit.

Features

• High S/N (88dB typ.).

• Low distortion (0.015% typ.).

• Weak signal muting dirve output having hysteresis.

• Tuning mete null (short) circuit.

• Signal meter dirve output having wide dynamic range.

• High limiting sensitivity.

• Built-in constant-voltage regulated circuit (Operating
voltage : 10 to 14V).

Specifications
Maximum Ratings

at Ta=25°C

Parameter Symbol Conditions Ratings Unit

Maximum supply voltage V

CC

max Pin 11 16 V

Input voltage V

IN

Pins 1 to 2 ±1 Vp-p

Supply current I

CC

Pin 11 40 mA

Flow-in current I

5

Pin 5 3 mA

Flow-out current I

10

Pin 10 2 mA

I

13

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

Recommended Operating Conditions at Ta=25°C

Parameter Symbol Conditions Ratings Unit

Recommended supply voltage V

CC

10 to 14 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

Quiescent 21 30 mA

Current drain I

CC

VIN=100dBµ 22 31 mA

Detection output V

O

VIN=100dBµ, 400Hz, 100% mod. 310 430 590 mVrms

S/N V

IN

=100dBµ, 400Hz, 100% mod. 82 88 dB

–3dB limiting sensitivity V

IN(lim)

VO: –3dB, 400Hz, 100% mod. 25 31 dBµ

Muting sensitivity V

IN(mute)V12

=5.6V, R16=56kΩ, R15=50kΩ 40 50 dBµ

Muting attenuation mute(att) V

IN

=100dBµ, 400Hz, 100% mod. 80 100 dB

V

5

=3.5V

Muting bandwidth BW(mute) V

IN

=100dBµ, V12=3V 120 200 330 kHz

Muting driving output V

12(1)

Quiescent 5.6 6.2 6.8 V

V

12(2)

VIN=100dBµ 0 0.3 V

Total harmonic distortion THD V

IN

=100dBµ, 400Hz, 100% mod. 0.015 0.05 %

AM supperssion ratio AMR V

IN

=80dBµ, FM =400Hz, 100% mod, 45 60 dB

AM =1kHz, 30% mod.

Signal meter driving output V

13(1)

Quiescent 0 0.1 V

V

13(2)

VIN=35dBµ 0.1 0.5 V

V

13(3)

VIN=70dBµ 1.3 2.0 2.9 V

V

13(4)

VIN=100dBµ 2.2 3.5 5.0 V

Offset voltage V

6-10

Quiescent, pin 6 to 10 –0.8 0 +0.8 V

V

7-10

Quiescent, pin 7 to 10 –0.4 0 +0.4 V

Tuning meter null voltage V

7-10(null)

V5=7.5V, pin 7 to 10 –50 +5 +50 mV

IF-off voltage I

15(IF off)V2-3

=1V 5.6 7.5 V

LA1235

No.873-2/12

LA1235

No.873-3/12

Reference Pin Voltage

Unit (resistance : Ω, capacitance : F)

Pin No.

V

1

V

2

V

3

Quiescent

V

6

V

7

V

8

V

10

V

12

V

13

V

15

V

16

2.6

6.2

5.9

6.2

0

Condition Pin voltage (V)

Test Circuit

LA1235

No.873-4/12

• Setting of muting sensitivity, hysteresis width (Refer to the
equivalent circuit block diagram and application circuit).
Muting sensitivity and hysteresis width are set arbitarily by
varying resistors R

204

and R

205

connected to pins 15 and 16,

respectively. Muting sensitivity is set by varying R

204

; and

if R

204

is made larger, muting sensitivity will shift to the

weak signal side. Hysteresis width is set by varying R

205

;

and if R

205

is made larger, hysteresis width will narrow.
Next, how to set muting sensitivity is concretely described as
follows. In case of using R

204

=50kΩ (semifixed resistor)

and R

205

=56kΩ, the upper limit of current I16, 50µ A,

delivered from the signal meter driver at which muting is
turned ON is obtained from the first quadrant of Table for
muting adjustable lower limit calculation. Muting is turned
ON at I16≤50µ A. If I16≤50µ A, muting is already turned ON
at a point of input being stronger than the setting input and it
is impossible to adjust muting at the setting input. Therefore,
I16>50µ A is required at the setting input. The input at which
a sample with a small I16output meets 50µ A is obtained as
VIN=47dBµ . This input is the maximum value of muting
sensitivity, that is to say, the lower limit at with muting can
be set. The data for sample with a Small I16shown in this
Table is colose to the minimum value, but since samples
with values less than this munimum value may occur, a
margin of some dBµ must be allowed. From the above, the
minimum value for muting setting (muting ON input)
becomes 50dBµ for R

204

(semifixed resistor)=50kΩ and

R

205

=56kΩ.