LA1781M_09 Datasheet, PDF (11/48 Pages) Sanyo Semicon Device – For Car Radios Single-Chip Tuner IC

Continued from preceding page.
Pin No.
Pin function
29
HCC control input
LA1781M
Pin description
The high band frequency output is
controlled by a 0 to 1V input.
It can also be controlled by the MRC
output.
Use a resistor of at least 100kΩ when
controlling with the pin 32 FM S-meter
signal.
Equivalent circuit
VREF
32
29
+
1μF
30
Noise canceller input
31
AM/FM detector output
Pin 30 is the noise canceller input.
The input impedance is 50kΩ.
Pin 31 is the AM and FM detector
output
In FM mode, this is a low-impedance
output.
In AM mode, the output impedance is
10kΩ.
To improve the low band separation,
use a coupling capacitor of over 10μF.
VCC
FM
detector
output
31
10kΩ
VCC
AM
detector
30
Noise
canceller
50kΩ
4.2V
1μF
+
32
IF S-meter output and MRC
FM S-meter output block
DC input
MRC AC input block
Adjust the external 1kΩ resistor to
attenuate the MRC AC input and
control the circuit.
VCC
10kΩ
MRC input
32
+
1μF
1kΩ
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No.6038-11/48