Kenwood TK-8180 - Manual (Page 19)

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