LA1266 查看數據表（PDF） - SANYO -> Panasonic

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LA1266

AM/FM Tuner System Of Electronic Tuning Type

SANYO -> Panasonic 

LA1266

2. AM/FM changeover

• AM/FM changeover is made using pin 20 as shown right.

• However, the voltage on pin 20 relative to VCC (pin 7) must be within

the range of +0.1V to – 0.8V. If not within this range, distortion and

selectivity will get worse. A resistance of 68kΩ at the IFT cold terminal,

which is used to prevent the changeover circuit from malfunctioning,

68kΩ

must be connected.

3. Local OSC buffer output

• When local OSC buffer output waveform is saw-toothed at the SW mode, connect a reistance of 1.2kΩ or

thereabouts across pin 24 and GND.

4. 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

V9 – Modulation Frequency

speed is made faster at the autmatic channel select mode.

In thes 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 3.3µF to 10µF.

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.

Ω

Modulatin frequency – Hz

5. 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 pin 24 and pin 23 is large, a parasitic oscillation of approximately 100MHz

may occur in the buffer output (pin 24). In this case, connect a capacitance of approximately 30pF across pin 24 and

GND.

6. 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 be concrete, the pot core type is better than the screw type which is loose

in coupling. This prevents the local OSC frequency from turning third

resonance frequency related to the coupling coefficient.

7. Resistance across pin 8 and VDD

If pin 8 is used for stop signal (SD) only, without using LED, it is

recommended to fix resistance RL across pin 8 and VDD to be 51kΩ to

100kΩ.

8. To prevent whistle from worsening, make the pattern of AM output pin 15 as

short as possible.

9. AM, FM IF buffer output

Application of a voltage to pin 13 (STRQ) causes AM IF(455kHz) signal (at AM mode) and FM IF(10.7MHz) signal

(at FM mode) to be delivered at pin 11 and pin 10, respectively. It is recommended that the voltage to be applied to

No.2291-4/11

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