LA1781M_09 Datasheet, PDF (15/48 Pages) Sanyo Semicon Device – For Car Radios Single-Chip Tuner IC

Continued from preceding page.
Pin No.
Pin function
48
RF AGC bypass
57
RF AGC
50
IF bypass
51
FM IF input
52
IF input
LA1781M
Pin description
RF AGC rectification capacitor
The low frequency distortion is
determined as follows :
Increasing C48 and C57 improves the
distortion but makes the response
slower.
Reducing C48 and C57
aggravates the distortion but makes
the response faster.
Equivalent circuit
VCC
5.6V
48
+
3.3μF
10kΩ
Antenna
damping
For AGC use
57
+
47μF
Due to the high gain of the limiter
amplifer, care must be taken when
choosing the grounding point for the
limiter amplifer input capacitor to
prevent oscillation.
2.6V
10kΩ
50
0.022μF
330Ω
51
10kΩ
The input impedance is 2kΩ.
IF in
52
2kΩ
100Ω
53
IF amplifier output
56
IF amplifier input
• Input and output pin or the first IF
amplifier
• Inverting amplifier
V56 = 2V
Input impedance : RIN = 330Ω
V53 = 5.3V
Output impedance
ROUT = 330Ω
IF OUT 53
2.75V
VCC
300Ω
300Ω
IF IN 56
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