Kenwood TK-7180 6. Power Supply Circuit, 7. Display Circuit

TK-7180

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

Q807

IC803

AVR

IC807

AVR

Q803

Q806

Q804

Q808

IC804

AVR

Q805

Q809

Q810

Q811

IC805

AVR

IC802

DET

IC801

DET

Q801,D805

REG

SBC

CN401

CPU

Flash memory

EEPROM

Ext-I/O

CPU #17

: RST1

RTC IC

CPU #24

: INT

Power supply : 10.8~15.7V +B

TXC

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

IC901

AVR

TX/Busy

LED

RED

GRN

POWER

PSW

Q910

Q909

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

MIC

jack

IC902

CPU

Mask

ROM

Fig. 6 Power supply circuit

Fig. 7 Display circuit

CIRCUIT DESCRIPTION