LA1267 Datasheet, PDF (4/14 Pages) Sanyo Semicon Device – FM/AM Tuner of Electronic Tuning Type

LA1267
• LED lighting sensitivity setting for FM.
For the LED lighting sensitivity setting for FM, the IC input
Semifixed Variable Resistor for FM
may be 45dBµ to 60dBµ. With the variations in the front end
LED lighting sensitivity setting for FM
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
Ideal setting range
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
: (A) pin 19-used method and (B) pin 20-used method.
IC input – dBµ
• For (A), the voltage on pin 19 relative to V_CC (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 19-use method for AM/FM changeover
(B) Pin 20-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 24 and GND.
4. AM input pin
• It is desirable that the AM input pin (pin 21) be L-coupled to pin 20.
• Inputting to pin 21 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.2012-4/14