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KX-TG8225RUB KX-TG8225RUJ KX-TG8225RUM KX-TG8225RUR KX-TG8225RUW KX-TG8226RUB KX-TG8226RUJ KX-TG8226RUM KX-TGA820RUB KX-TGA820RUJ KX-TGA820RUM KX-TGA820RUR KX-TGA820RUW
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104
Size
2.98 MB
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PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS ANSWERING SYSTEM
File
kx-tg8225rub-kx-tg8225ruj-kx-tg8225rum-kx-tg8225ru.pdf
Date

Panasonic KX-TG8225RUB / KX-TG8225RUJ / KX-TG8225RUM / KX-TG8225RUR / KX-TG8225RUW / KX-TG8226RUB / KX-TG8226RUJ / KX-TG8226RUM / KX-TGA820RUB / KX-TGA820RUJ / KX-TGA820RUM / KX-TGA820RUR / KX-TGA820RUW Service Manual ▷ View online

7
KX-TG8225RU/KX-TG8226RU/KX-TGA820RU  
4 Technical Descriptions
4.1.
Block Diagram (Base Unit)
Analog
Front
End
To TEL_LINE
A
B
CN1
Bridge
Rect
 D3 D3
Hook Switch
Q
4
,Q
5
Audio
Bell/Caller ID
Interface
CPU
59
54
61
52
60
56
55
BELL
HOOK
Off-Hook Line Voltage
64 ADCO
A/D
D/A
ADPCM
Codec Filter
DSP
Speech Encoding
Speech Decoding
BMC
Burst Encoding
Burst Decoding
RF
Interface
18
19
TXDA
RXDA
21
20
22
SYCL
SYDA
SYEN
ANT1
ANT2
RF Module
18
16
2
31
8
21
14
13
12
12
13
XTAL
X
1
10.368
MHz
EEPROM
SCL
SDA
6
5
7
To AC Adaptor
CN2
Limit
Resistor
Charge
Detector
CHARGE
CONTACT
(Optional)
VUNREG
3.3V
Reg.
IC
1
2.5V
Reg.
Q
9
1.8V
Reg.
Q
8
3.3 V
2.5 V
1.8 V
BBIC
IC5
FLASH
MEMORY
(TAM)
TAM Companion IC
RESET
CS
CS
3
4
2
1
8
SCK
SI
SO
9
14
16
39
40
38
36
37
62
10
11
23
12
IC11
IC8
IC7
IC10
KX-TG8225/8226 BLOCK DIA
GRAM 
(BASE UNIT)
CLK
RST
8
 KX-TG8225RU/KX-TG8226RU/KX-TGA820RU
4.2.
Circuit Operation (Base Unit)
4.2.1.
Outline
Base Unit consists of the following ICs as shown in Block Diagram (Base Unit) (P.7).
• DECT BBIC (Base Band IC): IC7
- Handling all the audio, signal and data processing needed in a DECT base unit
- Controlling the DECT specific physical layer and radio section (Burst Module Controller section)
- ADPCM code filter for speech encoding and speech decoding (DSP section)
- Echo-cancellation and Echo-suppression (DSP section)
- Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
- DTMF receiver (DSP section)
- Clock Generation for RF Module
- ADC, DAC, timer, and power control circuitry
- All interfaces (ex: RF module, EEPROM, LED, Analog Front End, etc.)
• RF Module: IC10
- PLL Oscillator
- Detector
- Compress/Expander
- First Mixer
- Amplifier for transmission and reception
• EEPROM: IC5
- Temporary operating parameters (for RF, etc.)
• FLASH MEMORY: IC11
- Voice Prompt (TAM) D/L Area
- ICM/OGM Recording Area
• TAM Companion: IC8
- Voice data compression and decompression
- Speaker Amp
- LED Driver
• Additionally,
- Power Supply Circuit (+3.3 V, +2.5 V, +1.8 V output)
- Crystal Circuit (10.368 MHz)
- Charge Circuit
- Telephone Line Interface Circuit
9
KX-TG8225RU/KX-TG8226RU/KX-TGA820RU  
4.2.2.
Power Supply Circuit
The power is supplied to the DECT BBIC, RF Module, EEPROM, FLASH MEMORY, TAM Companion and Charge Contact from
AC Adaptor (+6.5 V) as shown in Fig.101. The power supply is as follows;
• DECT BBIC (IC7): 
CN2 (+6.5 V) 
→ IC1 → Q9 → IC7
CN2 (+6.5 V) 
→ IC1 → Q8 → IC7
• RF Module (IC10): 
CN2 (+6.5 V) 
→ IC1 → Q8 → IC10 (Radio Transceiver) (Digital)
CN2 (+6.5 V) 
→ IC1 → Q9 → IC10 (Radio Transceiver) (Analog)
CN2 (+6.5 V) 
→ IC1 → R125 → IC10 (Power AMP)
• EEPROM (IC5): 
CN2 (+6.5 V) 
→ IC1 → Q9 → IC5
• FLASH MEMORY (IC11): 
CN2 (+6.5 V) 
→ IC1 → IC11
• TAM Companion (IC8): 
CN2 (+6.5 V) 
→ IC1 → Q9 → IC8
CN2 (+6.5 V) 
→ IC1 → Q8 → IC8
• Charge Contact (TP16): 
CN2 (+6.5 V) 
→ R57 → R56 → R55 → D22 → TP16
<Fig.101>
10
 KX-TG8225RU/KX-TG8226RU/KX-TGA820RU
4.2.3.
Telephone Line Interface
<Function>
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
Bell & Clip (: Calling Line Identification Presentation: Caller ID) signal detection:
In the standby mode, Q3 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the L1T (A) and L1R (B) leads (when the telephone rings), the AC ring voltage is transferred as
follows;
• A 
→ C4 → R6 → R33 → IC7 Pin 60 (CID INp) 
• B 
→ C3 → R4 → R35 → IC7 Pin 52 (CID INn)
ON/OFF hook circuit:
In the standby mode, Q3 is open, and connected as to cut the DC loop current and to cut the voice signal. The unit is conse-
quently in an on-hook condition
When IC7 detects a ring signal or press the TALK Key onto the handset, Q4 turns on and then Q3 turns on, thus providing an
off-hook condition (DC current flows through the circuit) and the following signal flow makes the loop current.
• A 
→ D3 → Q3 → Q5 → R21 → R22 → D3 → B [OFF HOOK]
4.2.4.
Transmitter/Receiver
• Audio Circuits and DTMF tone signal circuits.
Base Unit and Handset mainly consist of RF Module and DECT BBIC. 
Base Unit and Handset transmit/receive voice signal and data signal through the antenna on carrier frequency.
Signal Path:
*Refer to Signal Route (P.14).
4.2.4.1.
Transmitter Block
The voice signal input from the TEL LINE interface goes to RF Module (IC10) through DECT BBIC (IC7) as shown in Block Dia-
gram (Base Unit) 
(P.7
)
The voice signal passes through the analog part of IC7 where it is amplified and converted to a digital audio stream signal. The
burst switch controller processes this stream performing encryption and scrambling, adding the various other fields to produce
the GAP (Generic Access Profile) standard DECT frame, assigning to a time slot and channel etc.
In IC10, the carrier frequency is changing, and frequency modulated RF signal is generated and amplified, and radiated from
antenna. Handset detects the voice signal or data signal in the circuit same as the following explanation of Receiver Block.
4.2.4.2.
Receiver Block
The signal of 1900 MHz band (1881.792 MHz ~ 1897.344 MHz) which is input from antenna is input to IC10 as shown in Block
Diagram (Base Unit)
 (P.7).
In IC10, the signal of 1900 MHz band is downconverted to 864 kHz signal and demodulated, and goes to IC7 as GAP (Generic
Access Profile) standard DECT frames. It passes through the decoding section burst switch controller where it separates out the
frame information and performs de-encryption and de-scrambling as required. It then goes to the DSP section where it is turned
back into analog audio. This is amplified by the analog front end, and goes to the TEL LINE Interface.
4.2.5.
Pulse Dialling
During pulse dialing the hookswitch (Q3, Q4) is used to generate the pulses using the HOOK control signal, which is set high
during pulses. To force the line impedance low during the “pause” intervals between dial pulses, the PULSE_DIAL signal turns
on Q2.
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