KX-TG2521CAT, KX-TGA251RUT - Panasonic Telephone Service Manual (repair manual). Page 7

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7
KX-TG2521CAT/KX-TGA251RUT
4 Technical Descriptions
4.1.
Block Diagram (Base Unit)
Analog
Front
End
T
o TEL_LINE
Bridge
Rect
 D3D3
Hook Switch
Q3,Q4,Q5
Audio
Bell/Caller ID
Interface
CPU
18
16
23
20
21
19
24
BELL
HOOK
Off-Hook Line Voltage
25
A/D
D/A
ADPCM
Codec Filter
DSP
Speech Encoding
Speech Decoding
BMC
Burst Encoding
Burst Decoding
RF
PLL
5
3
77
75
9
10
EEPROM
SCL
SDA
57
58
44
To AC Adaptor
Limit
Resistor
Charge
Detector
CHARGE
CONTACT
(Optional)
IC2
Q9
Q8
2.4V
Reg.
1.8V
Reg.
3.0 V
2.4 V
1.8 V
BBIC
IC401
IC7
KX-TG2521 BLOCK DIAGRAM 
(BASE UNIT)
MOD/DEMOD
Charge
Pump
43
2.5V
X
T
A
L
X
1
X1
1
0.3
68
M
H
z
IC801
R
X
n
R
X
p
T
X
p
T
X
n
P
on
P
S
E
L
V
D
D
-P
A
D
R
V
4
3
6
7
T
X
on
R
X
on
D801
6
72
AN
T1
AN
T2
9
8
AN
T1
ANT2
R
F
 P
A
ANT1
AN
T2
78
73
74
80
L
1
L
2
D
C
P
D
C
M
2
FLASH MEMORY
IC421
42
3.0V
54 
55
56 
53
TA
M-C
Sn
SP
I-DI
SP
I-DO
SP
ICL
K
IC3
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