Ordering number : EN1820C
Monolithic Linear IC
LA1265
FM/AM Tuner of Electronic Tuning Type
Functions |
Package Dimensions |
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FM : IF amplifier, quadrature detector, AF preamplifier, |
unit : mm |
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signal meter, tuning indicator drive output (common |
3059-DIP22S |
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with stop signal, muting drive output). |
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AM : RF amplifier, MIX, OSC (with ALC), IF amplifier, |
[LA1265] |
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detector, AGC, signal meter, tuning indicator drive |
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output (common with stop signal). |
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Features
•Minimum number of external parts required.
•Excellent S/N.
•Local OSC with ALC.
•Local OSC buffer.
•Tuning indicator pin (common with narrow-band stop signal and muting drive output).
•Variable stop sensitivity (variable separately for FM, AM)
•Low whistle.
•Signal meter pin.
Specifications
Maximum Ratings at Ta=25°C, See specified Test Circuit.
Parameter |
Symbol |
Conditions |
Ratings |
Unit |
Maximum supply voltage |
VCC max |
Pins 7, 8, 17 |
16 |
V |
Flow-in current |
I8 |
Pin 8 |
20 |
mA |
Flow-out current |
I20 |
Pin 20 |
1 |
mA |
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I22 |
Pin 22 |
2 |
mA |
Allowable power dissipation |
Pd max |
Ta≤ 60°C |
650 |
mW |
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 operating voltage |
VCC |
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8.5 |
V |
Operating voltage range |
VCC op |
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6 to 14 |
V |
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
N2897HA (KT)/40194HK/O077KI/D095KI/2255KI, TS No.1820-1/15
LA1265
Operating Characteristics at Ta=25°C, VCC=8.5V, See specified Test Circuit
Parameter |
Symbol |
Conditions |
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Ratings |
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Unit |
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min |
typ |
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max |
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[AM : f=1MHz] |
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Quiescent current |
Icco |
No input |
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18 |
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26 |
mA |
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Detection output |
VO1 |
VIN=20dBµ, 400Hz, 30% mod. |
30 |
50 |
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90 |
mV |
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VO2 |
VIN=80dBµ, 400Hz, 30% mod. |
110 |
160 |
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220 |
mV |
S/N |
S/N1 |
VIN=20dBµ |
16 |
20 |
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dB |
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S/N2 |
VIN=80dBµ |
49 |
54 |
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dB |
Total harmonic distortion |
THD1 |
VIN=80dBµ, 400Hz, 30% mod. |
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0.3 |
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1.0 |
% |
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THD2 |
VIN=107dBµ, 400Hz, 30% mod. |
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0.5 |
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2.0 |
% |
Signal meter output |
VSM 1 |
No input |
0 |
0 |
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0.2 |
V |
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VSM 2 |
VIN=80dBµ |
2.4 |
2.8 |
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3.1 |
V |
LED lighting sensitivity |
VLED on |
ILED=1mA |
15 |
24 |
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33 |
dBµ |
Local OSC buffer output |
VOSC |
fOSC=1.45MHz |
220 |
275 |
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330 |
mV |
[FM : f=10.7MHz] |
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Quiescent current |
Icco |
No input |
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20 |
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28 |
mA |
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Input limiting sensitivity |
–3dBL.S. |
3dB down, 400Hz, 100% mod. |
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31 |
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37 |
dBµ |
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Demodulation output |
VO |
VIN=10dBµ, 400Hz, 100% mod. |
240 |
330 |
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460 |
mV |
S/N |
S/N |
VIN=100dBµ |
78 |
84 |
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dB |
Total harmonic distortion |
THD |
VIN=100%dBµ, 400Hz, 100% mod. |
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0.03 |
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0.3 |
% |
Signal meter output |
VSM 1 |
No input |
0 |
0 |
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0.2 |
V |
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VSM 2 |
VIN=100dBµ |
1.5 |
2.7 |
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3.1 |
V |
LED lighting sensitivity |
LED-on |
ILED=1mA |
35 |
50 |
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65 |
dBµ |
LED lighting bandwidth |
LED-BW |
VIN=100dB, ILED=1mA |
90 |
120 |
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160 |
kHz |
AM rejection ratio |
AMR |
VIN=100dBµ, FM=400Hz |
45 |
60 |
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dB |
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100% mod. AM=1kHz 30% mod. |
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Allowable power dissipation, Pd max – mW
Ambient temperature, Ta – °C
No.1820-2/15
LA1265
Equivalent Circuit Block Diagram
S Carve
S meter
How to use the LA1265
1.LED lighting, muting drive output, stop signal (SD).
•For LED lighting, muting drive output, stop signal, the output at pin 8 is used.
•The voltage on pin 8, when tuned, turns from "H" to "L". (Active-Low)
•Signal bandwidth at pin 8.
–For AM, the bandwidth depends on the CF (BFU450CN) at pin 11. If a capacitor is connected in place of the CF, the bandwidth will get wider.
–For FM, the bandwidth depends on the resistance across pins
9 and 20. If the resistance is increased, the bandwidth will get narrower. R=15kΩ makes the bandwidth approximately
120kHz.
LED Lighting Bandwidth – Resistance across pins 9 and 20
LED lighting bandwidth – kHz
Resistance across pins 9 and 20 – kΩ
•Sensitivity adjustment of LED, muting, stop signal.
–For FM, the semifixed variable resistor across pin 13 and GND is used.
–For AM, the semifixed variable resistor across pins 13 and 14 is used. Be sure to start adjustment for FM, and then make adjustment for AM. For the stop signal sensitivity and FM stop signal bandwidth, the variations should be considered and it is recommended to use the semifixed variable resistor for adjustment.
•LED lighting sensitivity setting for AM.
For the LED lighting sensitivity setting for AM, it is desirable that the IC input be 30dBµ (antenna input : approximately 50dB/m). In this case, the value of VR1 is 30kΩ .
No.1820-3/15
LA1265
•LED lighting sensitivity setting for FM.
–For the LED lighting sensitivity setting for FM, the IC input may be 45dBµ to 60dBµ . With the variations in the front end considered, it is ideal that the IC input in a standard receiving set be 51dBµ to 54dBµ . The lower value of VR2 for the LED lighting sensitivity setting is as illustrated right. Since the variations in the front end cause the IC input setting sensitivity to vary, it is recommended to use a value of VR2 at an input voltage lower than a
standard setting by 6dB or greater. For example, if IC input 53dBµ is taken as a standard, use VR2≤ 100kΩ at IC
input 47dBµ .
2.AM/FM changeover
•Two selections are available for changeover as shown below
VR2 semifixed variable resistor value – kΩ
Semifixed Variable Resistor for FM
LED lighting sensitivity setting for FM
Ideal setting range
IC input – dBµ
: (A) pin 17-used method and (B) pin 18-used method.
•For (A), the voltage on pin 17 relative to VCC (pin 7) must be within the range of –0.8V to +0.1V. If not within this range, distortion and selectivity will get worse.
•For (A), a resistance of 68kΩ at the IFT cold terminal, which is used to prevent the changeover circuit from malfunctioning, must be connected.
(A) pin 17-use method for AM/FM changeover |
(B) Pin 18-used method for AM/FM changeover |
3.Local OSC buffer output
•When local OSC buffer output wave form is saw-toothed at the SW mode, connect a resistance of 1.2kΩ or thereabouts across pin 22 and GND.
4.AM input pin
•It is desirable that the AM input pin (pin 19) be L-coupled to pin 18.
•Inputting to pin 19 can be done by DC-cutting with a capacitor. However, an unbalance in the RF amplifier
(differential amplifier) causes gain drop and whistle worsening. 5. Capacitance across pin 9 and GND.
A large capacitance across pin 9 and GND may cause a misstop at an adjacent channel when the channel select speed is made faster at the automatic channel select mode. In this case, decrease the capacitance across pin 9 and GND. However, if too decreased, the LED will flutter at low modulation frequencies at the time of detuning. Therefore, it is recommended to fix the capacitance across pin 9 and GND to be 3.3µ F to 10µ F. The relation between modulation frequency and demodulation output voltage on pin 9 with the capacitance across pin 9 and GND as a parameter is shown right.
V9 – Modulation Frequency
Modulation frequency – Hz
No.1820-4/15
LA1265
6.If the coupling coefficient of the local OSC coil is small and an antiresonance point of approximately 100MHz is present or the stray capacitance across pins 22 and 21 is large, a parasitic oscillation of approximately 100MHz may occur in the buffer output (pin 22). In this case, connect a capacitance of approximately 30pF across pin 22 and GND.
7.AM OSC coil
Generally speaking, the following should be noted. Avoid winding with loose coupling between primary side and secondary side (especially SW1, SW2). To put it concretely, the pot core type is better than the screw core type which is loose in coupling. This prevents the local OSC frequency from turning third resonance frequency related to the coupling coefficient.
8. Resistance across pin 8 and VDD.
If pin 8 is used for the stop signal (SD) only, without using LED, it is recommended to fix resistance RL across pin 8 and GND to be 51kΩ to 100kΩ .
9. To prevent whistle from worsening, make the pattern of AM output pin 12 as short as
possible.
Input/Output Admittance
FM |
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Parameter |
Frequency |
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Admittance |
Unit |
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IF |
γi1 |
10.7MHz |
ri |
330 |
Ω |
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ci |
20 |
pF |
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AM |
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– |
Parameter |
Frequency |
– |
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Admittance |
Unit |
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AGC-off (V16=1.4V) |
AGC-on (V16=2.5V) |
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RF |
γi19 |
1MHz |
ri |
15 |
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16 |
kΩ |
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ci |
4 |
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4 |
pF |
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MIX |
γo17 |
500kHz |
ro |
– |
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– |
kΩ |
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co |
3 |
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3 |
pF |
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IF |
γi15 |
500kHz |
ri |
2 |
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2 |
kΩ |
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co |
10 |
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8 |
pF |
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Test Circuit : FM, AM-MW
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T1 4147-1457-177 (Sumida) |
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T2 HW-40174 (Mitsumi) |
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Unit (resistance : Ω , capacitance : F) |
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T3a HW-40130, T3b HW-40131 (Mitsumi) |
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No.1820-5/15
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