LA1265 Просмотр технического описания (PDF) - SANYO -> Panasonic

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LA1265

FM/AM Tuner of Electronic Tuning Type

SANYO -> Panasonic 

LA1265

• LED lighting sensitivity setting for FM.

– For the LED lighting sensitivity setting for FM, the IC

Semifixed Variable Resistor for FM

input may be 45dBµ to 60dBµ. With the variations in the

LED lighting sensitivity setting for FM

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

Ideal setting range

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

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.

V9 – Modulation Frequency

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 3.3µF 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.

Modulation frequency – Hz

No.1820-4/15

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