Power Supply Circuits; Port Allocations - Icom PMR446 Service Manual

4-4 POWER SUPPLY CIRCUITS

VOLTAGE LINE
LINE
BATT The voltage from the connected battery cells.
Common 3 V converted from the BATT line at
the 3V regulator circuit (IC6). The circuit outputs
3V
the voltage regardless of the power ON/OFF
condition.
Common 3 V converted from the BATT line at
+3V
the +3V regulator circuit (Q25, D4).
Receive 3 V cotrolled by the R+3 regulator circuit
R+3
(Q18) using the "RXV" signal from CPU (IC1).
Transmit 3 V converted from the BATT line at the
T+3 T+3 regulator circuit (Q27, Q28, Q101, D5) using
the "TXV" signal coming from CPU (IC1).

4-5 PORT ALLOCATIONS

4-5-1 CPU (MAIN unit; IC1)
Pin Port
number name
Outputs VCO oscillation frequency
4 SHIFT control signal for Tx/Rx.
Low : While transmitting
Input port for the PTT switch from the
external mic jack (MAIN unit; J1).
31 PTT2
Low : External PTT switch is ON.
Input port for the internal PTT switch.
34 PTT1
Low : While PTT switch is pushed.
Input port for the [DOWN] switch.
35 DOWN
Input port for the [UP] switch.
36 UP
Input port for the [MODE] switch.
37 MODE
Input port for the POWER switch.
Low : While POWER switch is
38 POWSW
46 BEEP Outputs beep audio signal.
Outputs volume mute switch (Q23)
control signal.
48 RMUTE
High : While squelched
Outputs control signal for the AF ampli-
49 AFON
fier regulator circuit (Q5, Q10, Q11).
High: When squelch is open.
Outputs clock signal to the PLL IC (RF
50 PLLCK
unit; IC1).
DESCRIPTION
Description
pushed.
Pin Port
number name
Outputs data signals to the PLL IC (RF
51 PLLDA
unit; IC1).
Outputs strobe signals for the PLL IC
52 PLLST
(RF unit; IC1).
Outputs control signal for the +3V reg-
53 POWER
ulator circuit (MAIN unit; Q25, D4).
CTCO0–
Output port for the CTCSS signals.
54–56
CTCO2
Outputs control signal for the micro-
phone amplifier (IC2).
57 TXMOD
Input port for the CTCSS decode sig-
58 CTCIN
nals.
59 SQLIN Input port for squelch level signal.
Input ports for the control signal from
60 REMIN
the external remote microphone.
Input port from the connected battery
61 BATIN
pack for low battery indication.
Input port for the RSSI signal from the
62 SENIN FM IF IC (RF unit; IC2) to detect receiv-
ing signal strength level.
Outputs clock signal to the EEPROM
73 EEPCK
(IC3).
Outputs data signals to the EEPROM
74 EEPDA
(IC3).
Output port for power save function,
applied to VCO regurator circuit (RF
75 PSC
unit; Q13, Q14, D8, D9).
Outputs the R+3 regulator control sig-
76 RXV
nal (Q25, D4).
Outputs the T+3 regulator control sig-
77 TXV
nal (Q27, Q28, Q101, D5).
Outputs control signal for LCD back-
light.
78 LAMPC
Outputs internal microphone control
signal.
79 MICSW
Outputs MIC mute signal for RING
function.
80 MMUTE
4 - 3
Description
Low : While microphone amplifier is
ON.
Low : While LCD backlight is ON.
High : While internal PTT switch is
pushed.
High : While RING signals are out-
put, etc.