Power Supply Circuits; Port Allocations - Icom IC-F620 Service Manual

4-4 POWER SUPPLY CIRCUITS

4-4-1 VOLTAGE LINES (MAIN unit)
Line
The voltage from a DC power supply.
HV
The same voltage as the HV line which is con-
trolled by the power switching circuit (Q23, Q24).
When the [POWER] switch is pushed, the CPU
VCC
outputs the "PWON" control signal to the power
switching circuit to turn the circuit ON.
Common 5 V for the CPU converted from the HV
line by the CPU5V regulator circuit (IC10). The
CPU5V
circuit outputs the voltage regardless of the
power ON/OFF condition.
Common 8 V converted from the VCC line by the
8V
8V regulator circuit (IC9).
Common 5 V converted from the VCC line by the
5V
5V regulator circuit (Q27, Q28).
Receive 8 V controlled by the R8 regulator circuit
R8V (Q26, Q30, D24) using the "TXC" signal from the
CPU (IC20, pin 16).
Transmit 8 V controlled by the T8 regulator circuit
(Q25, Q29, D23) using the "TMUT" signal from
T8V
the CPU (IC20, pin 17).

4-5 PORT ALLOCATIONS

4-5-1 OUTPUT EXPANDER (FRONT unit; IC1)
Pin Port
number name
1–3 KS0–KS2 Output ports for key matrix.
Outputs LCD backlight control signal.
4 DIM1
Low : While LCD backlight is dim.
Outputs LCD backlight control signal.
5 DIM2
Low : While LCD backlight is OFF.
Outputs high-pass filter's characteris-
6 FSW
tics select signal.
Outputs external device control signal.
High : When matched 2/5-tone signals
7 HORN
SEG1–SEG40,
12–55 Output ports for LCD control signal.
COM1–COM4
4-5-2 OUTPUT EXPANDER (MAIN unit; IC7)
Pin Port
number name
Output tunable band pass filter control
1–3 T1–T3
signals.
Output port for
tunable band pass filter control signal
4 T4 while receiving.
output power control signal while
transmitting.
Description
Description
are received.
Description
4-5-3 CPU (MAIN unit; IC20)
Pin Port
number name
1 DSDA
2 DAST
8, LINH,
9 LCS
10 LCK
11 LSO
13 PLST
16 TXC
17 TMUT
18 AFON
19 NWC
20 DDSD
21 DDAC
22 SO
23 SI
24 SCK
25 CCS
KR2–
26–28
KR0
29 PTTO
30 HANG
31 BUSY
32 RMUT
4 - 4
Description
I/O port for data signals from/to the D/A
converter (IC7).
Outputs strobe signals for the level
controller (or D/A converter) (IC6).
Output ports for LCD control signals to
the LCD driver (FRONT unit; IC1)
Outputs clock signal for the LCD driver
(FRONT unit; IC1)
Outputs data signals for the LCD driver
(FRONT unit; IC1)
Outputs strobe signals for the PLL IC
(IC4).
Outputs R8 regulator circuit (Q26, Q30,
D24) control signal.
Outputs T8 regulator circuit (Q25, Q29,
D23) control signal.
Outputs control signal for the AF regu-
lator circuit (Q39, Q40, D31).
High : While AF amplifier (IC8) is acti-
vated.
Outputs IF bandwidth control signal.
High : While IF bandwidth is narrow.
Input port for the data signals from the
DTMF decoder (IC19).
Outputs clock signal to the DTMF
decoder (IC19).
Outputs data signals to the PLL IC
(IC4), level controller (or D/A converter)
(IC6), compander IC (IC14) and option-
al board (connect to J1).
Input port for the clock signal from the
optional board via J1.
Outputs clock signal to the PLL IC
(IC4), level controller (or D/A converter)
(IC6), D/A converter (IC7), compander
IC (IC14) and optional board (connect
to J1).
Outputs chip select signal for the
optional board via J1.
Input ports for the key matrix.
Input port for the PTT switch from the
optional board via J1.
Low : External PTT switch is ON.
Input port for the microphone hanger
detection signal.
Low : Microphone on hook
Outputs BUSY detection signal for the
optional board via J1.
Input port for AF mute signal from the
optional board via J1.