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.
Functions
. IF amplification/limiter
. Quadrature detector
. AF preamplifier
. AFC output
. Signal meter output
. AGC output
. Muting bandwidth
. Muting under weak signal strength
Features
. Versatile muting
Package Dimensions
unit : mm
3020A-SIP16
[LA1140]
SANYO : SIP16
a)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)
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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 (±VBE) 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.
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 |
Symbol |
Conditions |
Ratings |
Unit |
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Maximum supply voltage |
VCC max |
Pin 12 |
16 |
V |
Maximum supply current |
ICC max |
Pin 12 |
40 |
mA |
Allowable power |
Pd max |
Ta = 25°C |
640 |
mW |
dissipation |
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Ta = 70°C |
460 |
mW |
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Input voltage |
VIN |
Pin 1 to 2 |
±1 |
Vp-p |
Flow-in current |
I2 |
Pin 2 |
±0.2 |
mA |
|
I3 |
Pin 3 |
±0.2 |
mA |
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I6 |
Pin 6 |
2 |
mA |
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Flow-out current |
I5 |
Pin 5 |
1 |
mA |
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I13 |
Pin 13 |
2 |
mA |
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I14 |
Pin 14 |
2 |
mA |
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I15 |
Pin 15 |
1 |
mA |
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I16 |
Pin 16 |
1 |
mA |
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Operating temperature |
Topr |
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±20 to +70 |
°C |
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Storage temperature |
Tstg |
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±40 to +125 |
°C |
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Operating Conditions at Ta = 25°C
Parameter |
Symbol |
Conditions |
Ratings |
Unit |
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Recommended supply |
VCC |
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8 |
V |
voltage |
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Operating voltage range |
VCC op |
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7.5 to 16 |
V |
Operating Characteristics at Ta = 25°C, V CC = 8 V, f = 10.7 MHz, See specified Test Circuit
Parameter |
Symbol |
Conditions |
min |
typ |
max |
Unit |
Quiescent current |
ICCO |
Quiescent |
15 |
21 |
27 |
mA |
Current drain |
ICC |
VIN = 100 dBµ |
20 |
25 |
30 |
mA |
Demodulation output |
VO |
VIN = 100 dBµ, 400 Hz 100% mod. |
200 |
260 |
320 |
mVrms |
Total harmonic distortion |
THD |
VIN = 100 dBµ, 400 Hz 100% mod. |
|
0.05 |
0.2 |
% |
Signal-to-noise ratio |
S/N |
VIN = 100 dBµ, 400 Hz 100% mod. |
72 |
78 |
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dB |
Input limiting voltage |
VIN (lim) |
VO: 3 dB down, 400 Hz 100% mod. |
|
25 |
29 |
dBµ |
Muting sensitivity |
VIN (Mute) |
V14 = 2.0 V |
22 |
26 |
32 |
dBµ |
Muting attenuation (1) |
Mute (ACC) |
V6 = 2.0 V (22 kΩ), VIN = 100 dBµ, |
10 |
15 |
20 |
dB |
400 Hz 100% mod. |
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Muting attenuation (2) |
Mute (ACC) |
V6 = 5.0 V (22 kΩ), VIN = 100 dBµ, |
24 |
28 |
32 |
dB |
400 Hz 100% mod. |
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Muting bandwidth |
BW (Mute) |
VIN = 100 dBµ, V14 = 2.0 V |
140 |
210 |
370 |
kHz |
AM rejection ratio |
AMR |
VIN = 100 dBµ, FM 400 Hz |
50 |
63 |
|
dB |
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100% mod., AM 1 kHz 30% mod. |
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Muting drive output |
V14-0 |
Quiescent |
3.5 |
4.2 |
5.0 |
V |
Muting drive output |
V14-100 |
VIN = 100 dBµ |
0 |
0 |
0.3 |
V |
Signal meter output (1) |
V15-0 |
Quiescent |
0 |
0.1 |
0.3 |
V |
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Signal meter output (2) |
V15-50 |
VIN = 50 dBµ |
0.8 |
1.4 |
2.0 |
V |
Signal meter output (3) |
V15-70 |
VIN = 70 dBµ |
1.6 |
2.4 |
3.2 |
V |
Signal meter output (4) |
V15-100 |
VIN = 100 dBµ |
4.5 |
5.3 |
6.0 |
V |
AGC output (1) |
V16-0 |
Quiescent |
3.5 |
4.1 |
4.5 |
V |
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AGC output (2) |
V16-100 |
VIN = 100 dBµ |
0 |
0.02 |
0.3 |
V |
Offset voltage (1) |
V7-13 |
Quiescent, pin 7 to 13 |
±0.25 |
0 |
+0.25 |
V |
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Offset voltage (2) |
V8-13 |
Quiescent, pin 8 to 13 |
±0.5 |
0 |
+0.5 |
V |
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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 |
Unit (resistance: Ω, capacitance: F) |
Ind. |
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.
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)).
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The muting drive output comes in three types: |
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1) |
Hole detector output which develops a voltage when C/N (carrier-to-noise |
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ratio) lowers under weak signal input conditions. |
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2) |
A reversed output of the signal strength indicating output (output at pin |
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15) |
Unit (resistance: Ω) |
3) |
A bandwidth limited muting drive output which develops a voltage when |
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the AFC output becomes higher than ±VBE during tuning-off operation. |
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 |
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Inverter |
(Offset) |
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(AGC output) |
(Signal meter output) |
(Muting drive output) |
By referring to the illustration, V14 is given by the formula: V14 = Vr ± (IO + I1 ± aI2)RL ± VBE.
Conditions are: Vr 4.9 V, IO 0.2 mA, a 2, RL = 22 kΩ, VBE 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 IO 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 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
|
Output |
R15-G higher |
|
AF |
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ANT Input |
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Muting by varying R15-G |
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AF Output |
R14-6 lower |
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ANT Input |
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Muting by varying R14-6 |
± dB |
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THD, |
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distortion |
N |
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O |
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, |
AMrejection AMR, Noise |
|
O |
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Demodulationoutput V |
Noise |
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Input voltage, VIN (pin 1) ± dBµ |
dB± |
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Muting = OFF |
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O |
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Demodulation output, V |
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Resistance between pin 5 and GND ± Ω |
V14 ± V |
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fO = 10.7 MHz |
output,drivemutingBandwidth |
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VIN = 100 dBµ |
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Pins 7 ± 13 = 5.1 kΩ |
Frequency detuned, f ± kHz
Allowable power dissipation, Pd max ± mW
Pin voltage V14, V15, V16 ± V
Muting attenuation, Mute (Att) ± dB
Current drain, ICC ± mA
Ambient temperature, Ta ± °C
f = 10.7 MHz, non-modulation
Input voltage, VIN (pin 1) ± dBµ
VCC = 8 V
Resistance between pin 5 and GND is 100 kΩ
V6 through 22 kΩ ± V
1 Tuned, muting OFF
2 ± 200 kHz detuned, muting OFF
3 ± 200 kHz detuned, muting ON
Input voltage, VIN (Pin 1) ± dBµ
No. 729-5/15
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