Icom IC F121S, IC F110S, IC F111S service manual Output Expander Main unit IC6

4-4 POWER SUPPLY CIRCUITS

4-4-1 VOLTAGE LINES (MAIN UNIT)

Line	Description
HV	The voltage from a DC power supply.
	The same voltage as the HV line which is con-
	trolled by the power switching circuit (Q23, Q24).
VCC	When the [POWER] switch is pushed, the CPU
	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
CPU5V	line by the CPU5V regulator circuit (IC10). The
	circuit outputs the voltage regardless of the
	power ON/OFF condition.
8V	Common 8 V converted from the VCC line by the
	8V regulator circuit (IC9).
5V	Common 5 V converted from the VCC line by the
	5V regulator circuit (Q27, Q28).
	Receive 8 V controlled by the R8 regulator circuit
R8V	(Q26, Q30) using the “RXC” signal from the CPU
	(FRONT unit; IC1, pin 18).
	Transmit 8 V controlled by the T8 regulator circuit
T8V	(Q25, Q29, D23) using the “TMUT” signal from
	the CPU (FRONT unit; IC1, pin 40).

4-5 PORT ALLOCATIONS

4-5-1 LED DRIVER (FRONT UNIT; IC4)

Pin	Port	Description
number	name
5–11	CH1–CH4	Output LEDs control signals.
	LP0–LP2	Low : While LEDs are ON.
14	RLED	Outputs BUSY LED control signal.
15	TLED	Outputs TX LED control signal.
16	LIGT1	Outputs LED bright control signal.
17	LIGT2	Outputs backlight control signal.
		Outputs external device control signal.
18	HORN	High : When matched 5/2 tone signals
		are received.

4-5-2 OUTPUT EXPANDER (MAIN unit; IC6)

Pin	Port	Description
number	name
2	VOUT1	Outputs squelch control signal.
3	VOUT2	Outputs deviation (Tone) control signal.
10	VOUT3	Outputs deviation control signal.
11	VOUT4	Outputs DTCS control signal.
14	VOUT5	Outputs RX BPF control signal.
15	VOUT6	Outputs AGC control signal.
22	VOUT7	Outputs TX RF power control signal.
23	VOUT8	Outputs PLL reference control signal.

4-5-3 CPU (FRONT UNIT; IC1)

Pin	Port	Description
number	name
1	TEMP	Input port for the internal temperature.
2	BATV	Input port for low voltage detection
		from the connected power supply.
7	RES	Input port for the reset signal.
13, 14	SENC0,	Output ports for 5/2 tone and DTMF
	SENC1	signals.
15	CSFT	Outputs the CPU clock shift signal.
		Outputs the cut-off frequency control
16	DUSE	signal to the low-pass filter (MAIN; unit
		IC5) for CTCSS/DTCS switching.
17	UNLK	Input port for the PLL unlock signal
		from the PLL IC (MAIN unit; IC4).
18	RXC	Outputs the R8V regulator circuit
		(MAIN unit; Q26, Q30) control signal.
19, 20	SENC0,	Output ports for 5/2 tone and DTMF
	SENC1	signals.
21, 22	P0, P1	Input ports for key matrix.
23–25	CENO0–	Output ports for CTCSS/DTCS signals.
	CENO2
26, 27	P2, P3	Input ports for key matrix.
		Outputs clock signal to the PLL IC
		(MAIN unit; IC4), D/A converter (MAIN
28	SCK	unit IC6), LED driver (FRONT unit; IC4)
		and optional board (connect to MAIN
		unit; J1).
		Outputs data signal to the PLL IC
		(MAIN unit; IC4), D/A converter (MAIN
29	SO	unit; IC6), LED driver (FRONT unit;
		IC4) and optional board (connect to
		MAIN unit; J1).
30	BEEP	Output port for beep sound signal.
31	ESDA	I/O port for the data signal for the EEP-
		ROM (FRONT unit; IC3)
32	ESCL	Outputs clock signal for the EEPROM
		(FRONT unit; IC3).
33	MMUT	Input port for the MIC mute signal from
		the optional board via MAIN unit, J1.
34	RMUT	Input port for the AF mute signal from
		the optional board via MAIN unit, J1.
36	PLST	Outputs strobe signal for the PLL IC
		(MAIN unit; IC4).
37	DAST	Outputs strobe signal for the D/A con-
		verter IC (MAIN unit; IC6).
38	EXST	Outputs strobe signal for LED driver IC
		(FRONT unit; IC4).
39	EXOE	Outputs control signal for the LED dri-
		ver IC (FRONT unit; IC4).
40	TMUT	Outputs the T8V regulator circuit
		(MAIN unit; Q25, Q29, D23) control
		signal.

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