I/O Expander Ic - Icom IC-F410 Service Manual

4-5-2 I/O expander IC

(1) IC12 (MAIN unit)
Pin Port
number name
Output tunable band pass filter control
2, 3, 10 T1–T3
signals.
Output port for
tunable band pass filter control signal
11 T4
while receiving.
output power control signal while
transmitting.
Output port for reference frequency
14 REF
control voltage.
(2) IC13 (MAIN unit)
Pin Port
number name
Outputs control signal for the R8 regu-
4 TXC
rator circuits (MAIN unit; Q10, Q11).
High: While transmitting.
Outputs control signal for the T8 regu-
5 TMUT rator circuits (MAIN unit; Q8, Q9).
High: While Tx is muted.
Outputs AF mute switch (MAIN unit;
IC11) control signal for the receiver cir-
6 RM
cuit.
High: While no receive audio is emit-
Outputs MIC mute control signal.
7 MM High: While DTMF signals are output,
Outputs external device control signal.
High: When matched 2/5-tone signals
11 HORNO
Outputs control signal for the AF ampli-
12 AFATT fier regulator circuit.
High: When squelch is open, etc.
Outputs AF
13 AFHPF High: Filters out CTCSS or DTCS fre-
Outputs receive/transmit passband
width control signal.
14 NWC
High: While narrow bandwidth is
Description
Description
ed.
etc.
are received.
filter control signal.
quency.
selected.
4 - 5