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Model
KX-TG7207UAJ KX-TG7207UAM KX-TG7207UAS KX-TG7207UAT KX-TG7208UAM KX-TG7208UAS KX-TG7208UAT KX-TGA720UAJ KX-TGA720UAM KX-TGA720UAS KX-TGA720UAT
Pages
88
Size
2.32 MB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS PHONE
File
kx-tg7207uaj-kx-tg7207uam-kx-tg7207uas-kx-tg7207ua.pdf
Date

Panasonic KX-TG7207UAJ / KX-TG7207UAM / KX-TG7207UAS / KX-TG7207UAT / KX-TG7208UAM / KX-TG7208UAS / KX-TG7208UAT / KX-TGA720UAJ / KX-TGA720UAM / KX-TGA720UAS / KX-TGA720UAT Service Manual ▷ View online

10
KX-TG7207UA/KX-TG7208UA/KX-TGA720UA
4.3.
Block Diagram (Handset)
SPEAKER
RECEIVER
MIC
CHARGE
CIRCUIT
Q4,Q5,Q9
R7
CHARGE
CONTACTS
CHARGE(+)
CHARGE(-)
CHARGE
CHARGE DETECT
EEPROM
SCL
SDA
SWITCHED
SUPPLY
    Q1
Q1
BATTERY
TERMINAL
D7
VBAT1
DC/DC-SWITCH
J1
J2
2.5 V
Q3
1.8 V
Q2
3.3 V
2.5 V
1.8 V
LCD
RS
RESET
CS
SI
 SCL
CPU
Analog
Front
End
D/A
A/D
38
36
81
82
88
85
77
65
53
52
 73
69
  74
75
2
 22
23
95
98
ADPCM
Codec
Filter
DSP
Speech
Decoding
Speech
Encoding
BMC
Burst
Decoding
Burst
Encoding
RF
Interface
RF
Module
IC4
9
8
RXDA
TXDA
 5
 4
 3
SYDA
SYEN
SYCL
13
11
XTAL
X1
10.368
MHz
BATTERY
76
ON SWITCH
KEYPAD
ROWS
COLUMNS
25,47,97,100
6,7,43,44,45,95
BBIC
IC1
IC3
 24
LCD-BACK  LIGHT
KEY-BACK  LIGHT
 1
KX-TGA720 BLOCK DIAGRAM (HANDSET)
11
KX-TG7207UA/KX-TG7208UA/KX-TGA720UA
4.4.
Circuit Operation (Handset)
4.4.1.
Outline
Handset consists of the following ICs as shown in Block Diagram (Handset) (P.10).
• 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 Module: IC4
- PLL Oscillator
- Detector
- Compress/Expander
- Amplifier for transmission and reception
• EEPROM: IC3
- Temporary operating parameters (for RF, etc.)
4.4.2.
Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Handset, the voltage is as follows;
BATTERY(2.2 V ~ 2.6 V: J1) 
→ F1, L1, D1 → Q2 (1.8 V), Q3 (2.5 V), Q1 (3.3 V)
The Reset signal generates IC1 (66 pin) and 1.8 V.
4.4.3.
Charge Circuit
Circuit Operation:
When charging the handset on the Base Unit, the charge current is as follows;
DC+(6.5 V) 
→ R57 → R56 → R55 → D22 → CHARGE+(Base) → CHARGE+(Handset) → L4 → Q4 → D7→ F1 → BAT-
TERY+... Battery... 
BATTERY- 
→ L8 → R45 → GND → L5 → 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 Q5 of Handset.
Refer to Fig.101 in Power Supply Circuit (P.8).
4.4.4.
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;
• 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.
4.4.5.
Speakerphone
The hands-free loudspeaker at SP+ and SP- is used to generate the ring alarm.
12
KX-TG7207UA/KX-TG7208UA/KX-TGA720UA
4.5.
Circuit Operation (Charger Unit)
4.5.1.
Power Supply Circuit
The power supply is as shown.
13
KX-TG7207UA/KX-TG7208UA/KX-TGA720UA
4.6.
Signal Route
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