35
1
X-IN
I
A crystal oscillator (4.5MHz) is connected between these pins.
22
X-OUT
O
2
NC
Not connected.
3
CE
I
To enable the IC. Active "H".
4
DI
I
Digital data input from CPU (UPD780228GF-083) when relevant key is operated.
Active "H".
5
CL
I
To clock in the data DI.
6
DO
O
Digital data output to CPU (UPD780228GF-083)).
7
T-BASE
O
Outputs a reference clock signal (8Hz) for the clock.
8
MONO / BEAT
O
Outputs "H" when MONO / BEAT is switched.
Output "L" or "H" as follows:
9
FM / SW
O
2 BAND
3 BAND
3 BAND
AM
FM
LW
MW
FM
MW
SW
FM
H
L
H
H
L
H
L
L
Outputs "L" or "H" as follows:
10
MW / SW
O
2 BAND
3 BAND
3 BAND
AM
FM
LW
MW
FM
MW
SW
FM
L
L
H
L
L
L
H
L
11
IF-MUTE
O
To control internal counter.
12
IF-IN
I
General purpose counter input.
13
TUNE
I
Receives "L" when station is tuned.
14
NC
Not connected.
15
AM-IN
I
Receives the AM local oscillator frequency signal.
16
FM-IN
I
Receives the FM local oscillator frequency signal.
17
VDD
Supply power to IC (+5V).
18
PD
O
PLL charge pump output.
19
A-IN
I
The MOS transistor used for PLL active low pass filter.
20
A-OUT
O
Ground.
Pin No.
Pin Name
I/O
Description
IC, LC72131D-N
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2
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