Ordering number: EN 729E
Monalithic Linear IC
LA1140
FM IF System for Car Radio
Overview
The LA1140 is an IF system IC designed for FM car stereo
receivers. It features versatile muting characteristics and allows
receiver designers to realize the muting performance according
to their design concept. Since the muting characteristics can be
varied with a switch or a semi-fixed resistor, DX-Local
switching will be accomplished with ease.
Package Dimensions
unit : mm
3020A-SIP16
[LA1140]
Functions
.
IF amplification/limiter
.
Quadrature detector
.
AF preamplifier
.
AFC output
.
Signal meter output
.
AGC output
.
Muting bandwidth
.
Muting under weak signal strength
Features
SANYO : SIP16
.
Versatile muting
When muting operation is performed under a weak signal
strength, an attenuation slope of the audio output against
the input signal strength variations can be set at any given
value.
b) Maximum muting attenuation can be selected to be
approximately 6 to 40 dB.
c) Input signal strength level which actuates the muting
circuit can be set freely.
High limiting sensitivity (25 dBµ typ. with muting off)
provides a fine quieting characteristic.
High S/N (78 dB typ.)
Low distortion (0.05% typ.) avaiable if used with
double-tuned circuits.
Good AMR (63 dB typ. with 6 stages of differential IF
amplifiers).
Signal meter drive output proportional to the input signal
strength in dB (suitable to control multiplex IC LA3370).
Clamped (±V
BE
) AFC output, bandwidth adjustable.
Delayed AGC output for front end circuit.
Small space factor due to single-ended package employed.
3 mm pitch of pin terminals permitting ease-to-write PC
board pattern.
a)
.
.
.
.
.
.
.
.
.
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
93097HA(II)/D0994JN/N257TA/4105MW/3233KI,TS O090KI No.729-1/15
LA1140
Specifications
Maximum Ratings
at Ta = 25°C
Parameter
Maximum supply voltage
Maximum supply current
Allowable power
dissipation
Input voltage
Flow-in current
Symbol
V
CC
max
I
CC
max
Pd max
V
IN
I2
I3
I6
Flow-out current
I5
I13
I14
I15
I16
Operating temperature
Storage temperature
Topr
Tstg
Pin 12
Pin 12
Ta = 25°C
Ta = 70°C
Pin 1 to 2
Pin 2
Pin 3
Pin 6
Pin 5
Pin 13
Pin 14
Pin 15
Pin 16
Conditions
Ratings
16
40
640
460
±1
±0.2
±0.2
2
1
2
2
1
1
–20 to +70
–40 to +125
Unit
V
mA
mW
mW
Vp-p
mA
mA
mA
mA
mA
mA
mA
mA
°C
°C
Operating Conditions
at Ta = 25°C
Parameter
Recommended supply
voltage
Operating voltage range
Symbol
V
CC
V
CC
op
Conditions
Ratings
8
7.5 to 16
Unit
V
V
Operating Characteristics
at Ta = 25°C, V
CC
= 8 V, f = 10.7 MHz, See specified Test Circuit
Parameter
Quiescent current
Current drain
Demodulation output
Total harmonic distortion
Signal-to-noise ratio
Input limiting voltage
Muting sensitivity
Muting attenuation (1)
Muting attenuation (2)
Muting bandwidth
AM rejection ratio
Muting drive output
Muting drive output
Signal meter output
Signal meter output
Signal meter output
Signal meter output
AGC output (1)
AGC output (2)
Offset voltage (1)
Offset voltage (2)
Symbol
I
CCO
I
CC
V
O
THD
S/N
V
IN
(lim)
V
IN
(Mute)
Mute (A
CC
)
Mute (A
CC
)
BW (Mute)
AMR
V14-0
V14-100
V15-0
V15-50
V15-70
V15-100
V16-0
V16-100
V7-13
V8-13
Conditions
Quiescent
V
IN
= 100 dBµ
V
IN
= 100 dBµ, 400 Hz 100% mod.
V
IN
= 100 dBµ, 400 Hz 100% mod.
V
IN
= 100 dBµ, 400 Hz 100% mod.
V
O
: 3 dB down, 400 Hz 100% mod.
V14 = 2.0 V
V6 = 2.0 V (22 kΩ), V
IN
= 100 dBµ,
400 Hz 100% mod.
V6 = 5.0 V (22 kΩ), V
IN
= 100 dBµ,
400 Hz 100% mod.
V
IN
= 100 dBµ, V14 = 2.0 V
V
IN
= 100 dBµ, FM 400 Hz
100% mod., AM 1 kHz 30% mod.
Quiescent
V
IN
= 100 dBµ
Quiescent
V
IN
= 50 dBµ
V
IN
= 70 dBµ
V
IN
= 100 dBµ
Quiescent
V
IN
= 100 dBµ
Quiescent, pin 7 to 13
Quiescent, pin 8 to 13
min
15
20
200
72
22
10
24
140
50
3.5
0
0
0.8
1.6
4.5
3.5
0
–0.25
–0.5
typ
21
25
260
0.05
78
25
26
15
28
210
63
4.2
0
0.1
1.4
2.4
5.3
4.1
0.02
0
0
5.0
0.3
0.3
2.0
3.2
6.0
4.5
0.3
+0.25
+0.5
max
Unit
27
mA
30
mA
320 mVrms
0.2
%
dB
29
dBµ
32
dBµ
20
32
370
dB
dB
kHz
dB
V
V
V
V
V
V
V
V
V
V
(1)
(2)
(3)
(4)
No. 729-2/15
LA1140
Equivalent Circuit Block Diagram
AC Test Circuit
T1: CBTKAC-24782 AUO (Toko Co.)
T2: CBTKAE-24783X (Toko Co.)
22µH: S-220J (Korin Co.)
Input signal strength is an actual input at pin 1
Signal
strength
Ind.
Unit (resistance:
Ω,
capacitance: F)
Muting Characteristic
The muting operation in the LA1140 is performed by an AF preamplifier, the gain of which varies continuously with control
current, and a muting drive output circuit which supplies the control current.
The gain of the AF preamplifier decreases with increasing gain control current applied to pin 6. However, the gain does not
decrease further when the control current reaches approximately 120 µA or greater. The lower limit of the gain under this
condition depends upon a resistor connected between pin 5 and GND, and the higher the resistance the lower the gain (the higher
the attenuation). Thus the maximum muting attenuation will be set by connecting the resistor between pin 5 and GND.
AF output
AF output
R5-G (lower) 20 kΩ
R5-G (higher) 100 kΩ
No. 729-3/15
LA1140
Since the muting control input pin 6 is connected to the base of the emitter grounded transistor (through a protection resistor of
500
Ω
in series), the voltage between pin 6 and GND is about 0.6 V when the control current is applied. In actual cases, the
muting operation is accomplished by applying a voltage drive type muting drive output (pin 14 to pin 6 through a high resistance
(up to 20 kΩ)).
The muting drive output comes in three types:
1) Hole detector output which develops a voltage when C/N (carrier-to-noise
ratio) lowers under weak signal input conditions.
2) A reversed output of the signal strength indicating output (output at pin
15)
3) A bandwidth limited muting drive output which develops a voltage when
the AFC output becomes higher than
±V
BE
during tuning-off operation.
Unit (resistance:
Ω)
All these outputs are led to an OR circuit and the processed output is developed at pin 14. Of the above muting drive outputs,
descriptions on the hole detector output and the bandwidth limited muting drive output will be omitted, since they are the same as
those used in conventional quadrature detector ICs (such as LA1230, LA1231N).
The inverted output of the signal strength indication output is obtained as illustrated below.
Inverter
Inverter
Inverter
(Offset)
(AGC output)
(Signal meter output)
(Muting drive output)
By referring to the illustration, V14 is given by the formula: V14 = V
r
– (I
O
+ I1 – aI2)R
L
– V
BE
.
Conditions are: V
r
≅
4.9 V, I
O
≅
0.2 mA, a
≅
2, R
L
= 22 kΩ, V
BE
≅
0.6 V, I1 = V15/R15-G, I2 = V16/R16-G where V16 is a
constant equal to 4.1 V (typ) for medium or lower signal input levels, where the muting drive output is required. Since the V15
increases proportionally to the increase of the input signal strength, I1 will also increase. Therefore the V14 will decrease with
increasing signal strength. Thus the required muting drive output can be obtained by selecting proper values of R15-G and R16-G.
For example, the muting drive output moves toward strong input signal level
if the R16-G is decreased, or the muting drive output becomes zero due to the
offset current I
O
under a weak signal input condition, if the R16-G is
increased to infinity (namely pin 16 is opened). However the muting drive
output caused by a whole detector still exists in this case. Increasing R15-G
decreases the slope of the curve for the muting drive output vs. antenna signal
input level, or decreasing the R15-G increases the slope of the curve.
Furthermore, varying the value of a resistor connected between the muting
drive output (pin 14) and the muting control input (pin 6) changes the value of
ANT Input
the muting control current required to obtain the same muting drive output,
accordingly the slope of the curve for muting attenuation vs. antenna signal
input level is also changed. These characteristics investigated by using an
actual receiver are shown on the curves below.
The general method to adjust the muting circuit of the LA1140 is: to set the signal input level required to actuate the muting
circuit with the R16-G, to adjust the slope of the curve for the muting attenuation vs. antenna signal input with the R15-G, and to
adjust the maximum muting attenuation (determined by setting the noise level at no signal) with the R5-G. The slope of the curve
for the muting attenuation vs. antenna signal input level can also be adjusted by the resistor connected between pins 14 and 6 in
addition to R15-G, however, selecting a resistor too high does not allow the muting control current flowing into pin 6 to reach
120 µA even through the maximum muting drive output (V14) is applied, namely the muting attenuation does not reach its
maximum value. Accordingly a recommended value of the resistor between pins 14 and 6 is about 22 kΩ.
No. 729-4/15
LA1140
Allowable power dissipation, Pd max – mW
AF Output
R15-G higher
ANT Input
Muting by varying R15-G
AF Output
R14-6 lower
ANT Input
Muting by varying R14-6
Demodulation output V
O
, distortion THD,
– dB
AM rejection AMR, Noise N
O
Ambient temperature, Ta – °C
f = 10.7 MHz, non-modulation
Noise
Input voltage, V
IN
(pin 1) – dBµ
Muting attenuation, Mute (Att) – dB
Input voltage, V
IN
(pin 1) – dBµ
V
CC
= 8 V
Resistance
between pin 5 and
GND is 100 kΩ
Demodulation output, V
O
– dB
Muting = OFF
Resistance between pin 5 and GND –
Ω
Bandwidth muting drive output, V14 – V
Pin voltage V14, V15, V16 – V
V6 through 22 kΩ – V
1 Tuned, muting OFF
2 – 200 kHz detuned, muting OFF
3 – 200 kHz detuned, muting ON
Frequency detuned,
∆f
– kHz
Current drain, I
CC
– mA
f
O
= 10.7 MHz
V
IN
= 100 dBµ
Pins 7 – 13 = 5.1 kΩ
Input voltage, V
IN
(Pin 1) – dBµ
No. 729-5/15
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