DOWNLOAD Panasonic KX-TG6451CAT / KX-TGA641RUT Service Manual ↓ Size: 3.14 MB | Pages: 94 in PDF or view online for FREE

Model
KX-TG6451CAT KX-TGA641RUT
Pages
94
Size
3.14 MB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS PHONE
File
kx-tg6451cat-kx-tga641rut.pdf
Date

Panasonic KX-TG6451CAT / KX-TGA641RUT Service Manual ▷ View online

9
KX-TG6451CAT/KX-TGA641RUT
4.2.2.
Power Supply Circuit
The power is supplied to the BBIC,TAM Companion,Power AMP,LCD module,EEPROM,Flash Memory,LED,LCD backlight from
AC Adaptor(+6.5V) as shown in Fig 1.
When power line failure, the power is supplied to BBIC,TAM companion,EEPROM from telephone line instead of AC Adaptor
through D138 and Q341.
• BBIC (IC501) 
• TAM Companion (IC201) 
AC adaptor 
→ F301 → D301→ IC301 → D353 → IC201 (VDDPA 3.2V)
• RF Power AMP (IC801) 
AC adaptor 
→ F301 → D301→ IC304 → Q608 → IC801 (VCC)
• EEPROM (IC561) 
• Flash memory (IC541)
AC adaptor 
→ F301 → D301→ IC301 → D311 → IC501 (BAT:CP_VOUT1) → IC541 (VDD 3.0V)
• LCD module
AC adaptor 
→ F301 → D301→ IC301 → D311 → IC501 (BAT:CP_VOUT1) → CN1 → LCD module (VDD 3.0V)
• LED
AC adaptor 
→ F301 → D301→ IC301 → D311 → IC501 (BAT:CP_VOUT1) → CN1 → LED (3.0V)
• LCD backlight
AC adaptor 
→ F301 → D301 → IC301→ CN2 → LCD backlight (3.5V)
<Fig.1>
10
KX-TG6451CAT/KX-TGA641RUT
4.2.3.
Telephone Line Interface
Function
• Bell signal detection
• CLIP signal detection
• ON/OFF hook and pulse dial circuit
Bell & CLIP (Calling Line Identification Presentation: Caller ID) signal detection:
In standby mode,Q111/Q115 is open to cut the DC Loop current and decrease the ring load.
When ringing voltage appears at the TIP and RING, AC ring voltages transferred as followings;
CLIP signal detection
TIP 
→ C181 → R182 → R185 → IC501(26)(BBIC-CIDINn)
RING 
→ C191 → R192 → R195 → IC501(27)(BBIC-CIDINp)
Bell signal detection
TIP 
→ C181 → R182 → C184 → R186 → C187 → IC501(30)(BBIC-RINGING)
When power line failure (Because this case is no power to IC501)
TIP 
→ C164 → D161(2) → D161(1) →  IC101(1:5) → R167 → RINGERP
RING 
← D161(3) ← D161(4) ← Q162(c:e) ← IC101(2:8) ← RINGERM
ON/OFF hook circuit
ON hook:
Q111/Q115 is open to cut the DC loop current and voice signal, caused by the following control:
Hook switch (between hook2-4 and hook2-6) is opened and IC501(29)(Hook CTRL) is Low, (and Q114 is open), then Q112 is
OFF,so Q111/115 is OPEN
OFF hook:
Q111/Q115 is ON to make the DC loop current and be possible to transfer voice signal, caused by the following control:
Hook switch (between hook2-4 and hook2-6) make and IC501(29)(Hook CTRL) is High. (and Q114 is open), then Q112 is ON.
4.2.4.
Audio signal Flow (Out line)
The audio signal from Mic (for SP-phone and Corded Handset) is converted from Analog to digital in TAM companion IC(IC201),
then is transfered to BBIC(IC501) through PCM interface.
In BBIC(IC501), these data is converted to Analog, then send out tel line through tel line interface.
On the other hand, the audio signal from tel line is converted from Analog to digital in BBIC(IC501), then is transfered to TAM
companion IC(IC201) through PCM interface.
In TAM companion IC(IC201) ,these data is converted to Analog, then sound out from speaker.
Refer to the fig.2.
<Fig.2>
4.2.5.
RF cuircuit
BBIC(IC501) inclueds the RF transceiver circuit. (LNA,Mixer, IF filter, modulator/Demodulator,PLL, VCO etc).
This RF transceiver is interfaced  with Power-AMP(IC801) and Antenna circuit.
4.2.6.
Pulse Dialling
During pulse dialling 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.
11
KX-TG6451CAT/KX-TGA641RUT
4.3.
Block Diagram (Cordless Handset)
SPEAKER
RECEIVER
MIC
CHARGE
CIRCUIT
Q4, Q9, R7Q4,
Q9,
R7
CHARGE
CONTACTS
CHARGE(+)
CHARGE(-)
CHARGE_CTRL
CHARGE
EEPROM
SCL
SDA
BATTERY
TERMINAL
D7
VBAT
J1
J2
1.8 V
Q2
1.8 V
LCD
CD
RESET
CSB
SDA
 SCL
CPU
Analog
Front
End
D/A
A/D
33
35
15
16
19
20
32
31
57
58
 36
13
43
42
63
54
55
66
ADPCM
Codec
Filter
DSP
Speech
Decoding
Speech
Encoding
BMC
Burst
Decoding
RF PA
ANT1
IC801
Burst
Encoding
RF
PLL
MOD/DEMOD
5
3
4
3
6
7
8
9
2
77
78
75
RXn
RXon
ANT1
DA801
RXp
TXp
TXn
Pon
PSEL
TXon
VDD-PADRY
9
10
XTAL
X1
10.368
MHz
BATTERY
44
ON SWITCH
KEYPAD
Charge
Pump
ROWS
COLUMNS
CP3.0V
CP4.0V
48, 49, 50, 51
22, 23, 24, 25, 26
BBIC
IC1
IC3
 56
LCD-BACK  LIGHT
KEY   LED
BELL  LED
52
68
73
74
80
LDO_CTRL
KX-TGA641 BLOCK DIA
GRAM (CORDLESS HANDSET)
12
KX-TG6451CAT/KX-TGA641RUT
4.4.
Circuit Operation (Cordless Handset)
4.4.1.
Outline
Cordless Handset consists of the following ICs as shown in Block Diagram (Cordless Handset) (P.11).
• 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
• RF Power Amp: IC801
- Amplifier for transmission
• EEPROM: IC3
- Temporary operating parameters (for RF, etc.)
4.4.2.
Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Cordless Handset, the voltage is as follows;
BATTERY(2.2 V ~ 2.6 V: BATT+) 
→ F1 → Q2 (1.8 V), IC1-43pin (2.5V)
The Reset signal generates IC1 (61 pin) and 1.8 V.
4.4.3.
Charge Circuit
Circuit Operation:
When charging the Cordless Handset on the Charger Unit, the charge current is as follows;
DC+(6.5 V) 
→ F1 → R1 → CHARGE+(Charger) → CHARGE+(Cordless Handset) → L4 → Q4 → D7→ F1 → BATTERY+... Bat-
tery... 
BATTERY- 
→ L8 → R45 → GND → L5 → CHARGE-(Cordless Handset)→ CHARGE-(Charger) → GND → DC-(GND)
In this way, the BBIC on Cordless Handset detects the fact that the battery is charged.
The charge current is controlled by switching Q9 of Cordless Handset.
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.
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