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Power supply circuit, Display circuit, Tk-8180 – Kenwood TK-8180 User Manual

Page 19: Circuit description

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TK-8180

19

6. Power Supply Circuit

The block diagram of the power supply circuit is shown in

Figure 6.

Power is always supplied from +B to the circuit (5M, +B)

that is always started and the circuits (SB, 8C, 5E, 8T, 8R, 5C,
5R) controlled by the CPU (IC404). When +B is supplied to
the transceiver, Q801, D805 and IC805, regulate the voltage
(5M) which is supplied to the circuit around the CPU. The
CPU starts.

When the CPU detects that the +B voltage is higher than

the voltage prescribed by IC802, the transceiver power (SB)
is turned ON by controlling the SBC signal (Low: transceiver
power OFF, High: transceiver power ON).

The CPU controls the TXC signal (Low: Transmission sys-

tem power OFF, High: Transmission system power ON) dur-
ing transmission to supply power (8T) to the transmission cir-
cuit. The CPU controls the RXC signal (Low: Reception sys-
tem power OFF, High: Reception system power ON) during
reception to supply power (8R, 5R) to the reception circuit.

When the CPU detects the PSW (Power Switch) signal,

IGN (Ignition Sense) signal or INT signal, it controls the SBC
signal and turns the transceiver power (SB) OFF.

If +B is not provided to the transceiver, power is supplied

to only the RTC IC (IC402) through the secondary battery con-
nected with CN401 to back up the clock.

7. Display Circuit

The display unit consists of the Panel CPU (IC902), the

LCD driver (IC903), the TX/BUSY LED, the KEY detection, the
Backlight and the Microphone jack circuits.

The Panel CPU is a 16-bit microcomputer that contains a

64k-byte Mask ROM and a 2k-byte RAM.

The Panel CPU performs serial communication with the

Main CPU (IC404) on the TX-RX unit (B/3) and the Panel CPU
detects keys and sends data communication contents
through the MIC Jack to the Main CPU. The Panel CPU re-
ceives commands from the Main CPU and controls the dis-
play system.

The LCD operates with 1/9 duty under the LCD driver

(IC903) control. The LCD and KEY Backlights are controlled
by Q909. The display brightness of the LCD Backlight can be
changed.

D804

DET

Q802

SW

Q807

SW

IC803

AVR

IC807

AVR

Q803

SW

Q806

SW

Q804

SW

Q808

SW

IC804

AVR

Q805

SW

Q809

SW

Q810

SW

Q812

SW

IC805

AVR

IC802

DET

IC801

DET

Q801,D805

REG

5M

SBC

CN401

CPU
Flash memory
EEPROM
Ext-I/O

CPU #17
: RST1

RTC IC

CPU #24
: INT

Power supply : 10.8~15.7V

+B

SB

8C

8T

5E

TXC

8R

RXC

5C

5R

RXC

Final amp.

Audio amp, PA connector
Panel block, D-sub block

Internal option
Panel block

Internal option

TX-drive
APC block
ANT SW

IF block

VCXO, VCO, PLL IC
IF detection IC
DC/DC converter
D/A converter
MIC amp, AQUA
AF block

IF block

F801

5A

IC901

AVR

TX/Busy

LED

RED

GRN

POWER

SW

8C

PSW

Q910

Q909

SB

RST2

SHIFT

PSENS

SPO

GND

RXD, TXD

MIC, ME

HK, PTT, DM, BLC2

IC903

LCD

driver

Function

KEY

FKEY [1~10]

BLCI

LCD

back
light

KEY

back
light

DIMM

LCD

SB

MIC
jack

SP

IC902

CPU

Mask

ROM

Fig. 6

Power supply circuit

Fig. 7

Display circuit

CIRCUIT DESCRIPTION