Ordering number : EN873F
Monolithic Linear IC
LA1235
FM IF System Applications
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]
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).
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
LA1235
Specifications
Maximum Ratings at Ta=25°C
Parameter |
Symbol |
Conditions |
Ratings |
Unit |
Maximum supply voltage |
VCCmax |
Pin 11 |
16 |
V |
Input voltage |
VIN |
Pins 1 to 2 |
±1 |
Vp-p |
Supply current |
ICC |
Pin 11 |
40 |
mA |
Flow-in current |
I5 |
Pin 5 |
3 |
mA |
Flow-out current |
I10 |
Pin 10 |
2 |
mA |
|
I13 |
|
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 |
VCC |
|
10 to 14 |
V |
Operating Characteristics at Ta=25°C, VCC=12V, f=10.7MHz
Parameter |
Symbol |
Conditions |
|
Ratings |
|
Unit |
|
|
|
|
|
||||
|
|
|
min |
typ |
|
max |
|
|
|
|
|
|
|
|
|
Quiescent current |
ICCO |
Quiescent |
|
21 |
|
30 |
mA |
Current drain |
ICC |
VIN=100dBµ |
|
22 |
|
31 |
mA |
Detection output |
VO |
VIN=100dBµ, 400Hz, 100% mod. |
310 |
430 |
|
590 |
mVrms |
S/N |
|
VIN=100dBµ, 400Hz, 100% mod. |
82 |
88 |
|
|
dB |
–3dB limiting sensitivity |
VIN(lim) |
VO : –3dB, 400Hz, 100% mod. |
|
25 |
|
31 |
dBµ |
Muting sensitivity |
VIN(mute) |
V12=5.6V, R16=56kΩ , R15=50kΩ |
|
40 |
|
50 |
dBµ |
Muting attenuation |
mute(att) |
VIN=100dBµ, 400Hz, 100% mod. |
80 |
100 |
|
|
dB |
|
|
V5=3.5V |
|
|
|
|
|
Muting bandwidth |
BW(mute) |
VIN=100dBµ, V12=3V |
120 |
200 |
|
330 |
kHz |
Muting driving output |
V12(1) |
Quiescent |
5.6 |
6.2 |
|
6.8 |
V |
|
V12(2) |
VIN=100dBµ |
|
0 |
|
0.3 |
V |
Total harmonic distortion |
THD |
VIN=100dBµ, 400Hz, 100% mod. |
|
0.015 |
|
0.05 |
% |
AM supperssion ratio |
AMR |
VIN=80dBµ, FM =400Hz, 100% mod, |
45 |
60 |
|
|
dB |
|
|
AM =1kHz, 30% mod. |
|
|
|
|
|
|
|
|
|
|
|
|
|
Signal meter driving output |
V13(1) |
Quiescent |
|
0 |
|
0.1 |
V |
|
V13(2) |
VIN=35dBµ |
|
0.1 |
|
0.5 |
V |
|
V13(3) |
VIN=70dBµ |
1.3 |
2.0 |
|
2.9 |
V |
|
V13(4) |
VIN=100dBµ |
2.2 |
3.5 |
|
5.0 |
V |
Offset voltage |
V6-10 |
Quiescent, pin 6 to 10 |
–0.8 |
0 |
|
+0.8 |
V |
|
V7-10 |
Quiescent, pin 7 to 10 |
–0.4 |
0 |
|
+0.4 |
V |
Tuning meter null voltage |
V7-10(null) |
V5=7.5V, pin 7 to 10 |
–50 |
+5 |
|
+50 |
mV |
IF-off voltage |
I15(IF off) |
V2-3=1V |
5.6 |
|
|
7.5 |
V |
No.873-2/12
LA1235
Reference Pin Voltage
Pin No. |
Condition |
Pin voltage (V) |
|
|
|
V1 |
|
|
V2 |
|
2.6 |
V3 |
|
|
V6 |
|
6.2 |
V7 |
|
|
|
|
|
V8 |
Quiescent |
5.9 |
V10 |
|
6.2 |
V12 |
|
|
|
|
|
V13 |
|
|
V15 |
|
0 |
V16 |
|
|
Test Circuit
Unit (resistance : Ω , capacitance : F)
No.873-3/12
LA1235
•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 R204 and R205 connected to pins 15 and 16, respectively. Muting sensitivity is set by varying R204 ; and if R204 is made larger, muting sensitivity will shift to the weak signal side. Hysteresis width is set by varying R205 ; and if R205 is made larger, hysteresis width will narrow. Next, how to set muting sensitivity is concretely described as
follows. In case of using R204=50kΩ (semifixed resistor) and R205=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 I16 output 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 I16 shown 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 R204 (semifixed resistor)=50kΩ and R205=56kΩ .
No.873-4/12
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