LA1787M Datasheet, PDF (14/54 Pages) Sanyo Semicon Device – Single-Chip Tuner IC for Car Radios

Continued from preceding page.
Pin No.
Function
41
HCC capacitor
42
AM L.C. pin
43
Pilot detector
LA1787M
Description
The HCC frequency characteristics
are determined by the external
capacitor connected at this pin.
This pin is used to change the
frequency characteristics of the
unneeded audio band under
100 Hz in AM mode to produce
a clear audio signal.
Note: The LC capacitor must be
connected between this pin
and V_CC (pin 40).
This is because the detector
circuit operates referenced
to V_CC.
The cutoff frequency f_C is
determined by the following
formula.
f_C = 1/2π × 50 kΩ × C
Inserting a 1-MΩ resistor between
pin 43 and V_CC will force the IC
to mono mode.
Equivalent circuit
20kΩ
VCC
+
20kΩ
DET
VCC
41
2200pF
VCC
C
42
A13580
50kΩ 1kΩ
50kΩ 1kΩ
A13581
19kHz∠0°
BIAS
30kΩ
30kΩ
+
30kΩ
VCC
43
1µF
+
A13582
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No. 6655-14/54