Panasonic KX-TG6811UAB / KX-TG6811UAM / KX-TG6812UAB / KX-TG6821UAB / KX-TGA681RUB / KX-TGA681RUM Service Manual ▷ View online
13
KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.4.5.
Power Supply Circuit
The power supply voltage from AC adaptor is converted to VBAT (3.0V) in 3.0V Regulator (IC302). And +3.0V for peripherals
and analog part is insulated from VBAT by Doubler of BBIC.
Circuit Operation:
and analog part is insulated from VBAT by Doubler of BBIC.
Circuit Operation:
5.5V
VBAT
RSTN(Reset)
pin 54
VBAT
pin 10
pin 57
pin 9
pin 15
IC501
IC302
IC601
BBIC
DOUBLER OUT
For peripherals
For peripherals
VDDC (1.2V)
AC Adaptor
3.0V
REGULATOR
FLASH
IC611
EEPROM
+3.0V
STM/CKM
Receive
Amp.
MSG LED
Startmonitor
(IC501 57pin)
VDDC (1.2 V)
VBAT
Reset (RSTN)
(IC501_54 pin)
(IC501_54 pin)
BBIC chip initialize
(CKM/STM)
RF Part
LED
(TAM COUNTER)
(TAM COUNTER)
14
KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.4.5.1.
Charge Circuit
The voltage from the AC adaptor is supplied to the charge circuits.
D
3
62
R
3
72
R
3
71
CHARGE+
F301
DCP
CHARGE-
+5.5V
DCM
15
KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.5.
Block Diagram (Handset)
QSPI
FLASH MEMOR
Y
IC4
SPEAKER
RECEIVER
MIC
CHARGE
P
o
w
e
r F
ailer Mode
P
o
w
er Supply SW
CIRCUIT
Q2, Q3, Q4,Q
2
,
Q
3
,
Q
4
,
Q9, R8Q
9
,
R
8
CHARGE
CONT
A
C
TS
CHARGE(+)
CHARGE_CTRL
BA
TTER
Y_ON
CHARGE_DET
EEPR
O
M
SCL
SD
A
BA
TTER
Y
TERMINAL
R45
VBA
T
BA
TT
-
1.8 V
Q1
1.8 V
CP
2.8
V
LCD
CD
RESET
CSB
SD
A
SCL
CPU
Analog
F
ront
End
D/A
A/D
35
37
21
22
17
18
34
33
66
67
32
24
73
63
64
76
ADPCM
Codec
Filter
DSP
Speech
Decoding
Speech
Encoding
BMC
Burst
Decoding
ANT1
Burst
Encoding
RF
PLL
MOD/DEMOD
1
2
87
86
RXn
ANT1
RXp
TXp
TXn
7
8
XT
AL
X1
10.368
MHz
BA
TTER
Y
46
ON SWITCH
KEYP
AD
RO
W
S
COLUMNS
57, 58, 59, 60
1
1
, 12, 13, 14, 55
47, 48, 51, 53 QSPI-IO 0-3
44
45
Charge
Pump
CP3V
D3
CP2.8V
CP
4V
BBIC
IC1
IC3
65
KEY
LED
61
LDO_CTRL
CP
3.0
V
CP3V
QSPI
Control
52 QSPI-SCK
49 QSPI-CS
TGA681 only
79
Q10, Q1
1, Q12, R10
Q
1
0
,
Q
1
1
,
Q
1
2
,
R
1
0
KX-TGA681 BLOCK DI
A
GRAM (Handset)
LCD-BACK LIGHT
77
Reset
Reset
Pin 71
16
KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.6.
Circuit Operation (Handset)
4.6.1.
Outline
Handset consists of the following ICs as shown in Block Diagram (Handset) (P.15).
• DECT BBIC (Base Band IC): IC1
- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, DC/DC Converter, EEPROM, LCD, RF Power Amp.)
- PLL Oscillator
- Detector
- Compress/Expander
- Reception
- Integrated 1.9 GHz PA for DECT
- All interfaces (ex: Key, Detector Circuit, Charge, DC/DC Converter, EEPROM, LCD, RF Power Amp.)
- PLL Oscillator
- Detector
- Compress/Expander
- Reception
- Integrated 1.9 GHz PA for DECT
• QSPI FLASH MEMORY: IC4
- Main Program D/L Area
• EEPROM: IC3
- Temporary operating parameters (for RF, etc.)
4.6.2.
Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Handset, the voltage is as follows;
BATTERY(2.2 V ~ 2.6 V: BATT+)
BATTERY(2.2 V ~ 2.6 V: BATT+)
→ F1 → Q1 (1.8 V), IC1-44pin (3.0V)
The Reset signal generates IC1 (71 pin) and 1.8 V.
4.6.3.
Charge Circuit
Circuit Operation:
When charging the handset on the Base Unit, the charge current is as follows;
DC+(5.5 V)
→ R371 → R372 → D362 → CHARGE+(Base) → CHARGE+(Handset) →
→ Q3 → F1 → BATTERY+...
Battery...
BATTERY-
BATTERY-
→ R45 → GND → CHARGE-(Handset)→ CHARGE-(Base) → GND → DC-(GND)
In this way, the BBIC on Handset detects the fact that the battery is charged.
The charge current is controlled by switching Q9 of Handset.
The charge current is controlled by switching Q9 of Handset.
Refer to Fig.101 in Power Supply Circuit (P.13).
4.6.4.
Battery Low/Power Down Detector
Circuit Operation:
“Battery Low” and “Power Down” are detected by BBIC which check the voltage from battery.
The detected voltage is as follows;
The detected voltage is as follows;
• Battery Low
Battery voltage: V(Batt) 2.25 V ± 50 mV
The BBIC detects this level and "
" starts flashing.
• Power Down
Battery voltage: V(Batt) 2.0 V ± 50 mV
The BBIC detects this level and power down.
4.6.5.
Speakerphone
The hands-free loudspeaker at SP+ and SP- is used to generate the ring alarm.
1.8 V
Reset
(IC1_71pin)
(IC1_71pin)
Battery +
Q2
R8
R8
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