Icom IC-T90A manual CPU Logic Unit IC1

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

Pin	Port	Description
number	name
1	PATMP	Input port for the PA’s temperature
		while transmitting.
3	SD	Input port for the S-meter signal.
5	CHG	Input port for the battery voltage divide
		signal.
6	VIN	Input port for the power supply voltage
		divide signal.
7	CTCIN	Input port for the CTCSS decorded
		signal (67.0–254.1 Hz analog signal).
		Outputs the FM or WFM regulator
12	WFM	control signal.
		Low: FM or WFM mode is selected.
		Outputs the AM mode regulator con-
13	AM	trol signal.
		Low: AM mode is selected.
14	CLSFT	Outputs the clock shift control signal.
19	RESET	Input port for the CPU reset signal.
		High: The CPU is reset.
25	POWER	Input port for the [POWER] switch.
		Low: Power is ON.
		Input port for the external power sup-
26	CPUHV	ply connecting signal.
		Low: While the external power sup-
		ply is connected.
28	IOSTB	Outputs the expander IC (AF unit;
		IC51, pin 1) strobe signal.
29	DASTB	Outputs strobe signals to the D/A IC
		(RF unit; IC251, pin 2).
30	CLIN	Input port for the cloning signal.
31	CLOUT	Output port for the cloning signal.
		I/O port for the PLL IC (VCO unit;
33	PDAUL	IC201, pin 7) data signal.
		Low: PLL is unlocked.
		High: PLL is locked.
		Outputs clock signals to the R3V
34	CK	switch (AF unit; IC51, pin 3), D/A IC
		(RF unit; IC251, pin 3) and PLL IC
		(VCO unit; IC201, pin 4).
35	PLSTB	Outputs the PLL IC strobe signal.
40	ECK	Outputs the EEPROM clock signal.
42	CHGC	Outputs the battery charger control
		signal.
43	PCON	Outputs the +3C regulator control sig-
		nal.
		Outputs the R3C regulator control sig-
44	R3C	nal.
		Low: While receiving.
		Outputs the T5V regulator control sig-
45	TXC	nal.
		High: While transmitting.

Pin	Port	Description
number	name
46	MICC	Outputs the mic amplifier regulator
		control signal.
47	NOISE	Input port for the SQL detection noise
		signal.
		Outputs mute control signal.
48	MUTE	High: AF muting while receiving.
		MIC muting while transmitting.
49	AFON	Output AF amplifier regulator control
		signal.
51	BUSYL	Outputs BUSY LED control signal.
		High: The BUSY LED is ON.
52	GLED	Outputs key backlight control signal.
		High: Green backlight is ON.
53	RLED	Outputs key backlight control signal.
		High: Red backlight is ON.
54	LCDL	Outputs LCD backlight control signal.
		Low: Lights ON.
		Outputs the 430 MHz VCO regulator
55	V3C	control signal.
		Low: 430 MHz is selected.
56	DIUD	Input port for the up/down signal from
57	DICK	the main dial (AF unit; S251).
58–61	KS3–KS0	Output ports for key matrix.
62–65	I3–I0	Output ports for Initial matrix.
66–69	KR3–KR1	Input ports for key matrix.
		Outputs the 50 MHz VCO regulator
70	V1C	control signal.
		Low: 50 MHz is selected.
		Input port for the volume level control
71	VOLDN	signal.
		Low: Volume level is low.
		Input port for the volume level control
72	VOLUP	signal.
		Low: Volume level is high.
73	SQL	Input port for the [SQL] switch.
		Low: While [SQL] switch is pushed.
		Outputs the 430 MHz modulation cir-
74	430M	cuit control signal.
		Low: While 430 MHz is transmitting.
		Outputs the 144 MHz modulation cir-
75	144M	cuit control signal.
		Low: While 144 MHz is transmitting.
77	PTT	Input port for the [PTT] switch.
		High: While [PTT] switch is pushed.
		Outputs 144 MHz VCO regulator con-
81	V2C	trol signal.
		Low: 144 MHz is selected.
82	VSFT	Outputs the VCO select signal.

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