Circuit Operation (Handset); Circuit Operation (Charger Unit) - Panasonic KX-TG1711MEB Service Manual

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): IC103
- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, DC/DC Converter, EEPROM, LCD)
- PLL Oscillator
- Detector
- Compress/Expander
- Amplifier for transmission and reception
• EEPROM: IC102
- Temporary operating parameters
4.4.2. Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Handset, the voltage is as follows;
~
B A T T E R Y ( 2 . 2 V 2 . 6 V )
The Reset signal generates R121, C186 and
4.4.3. Charge Circuit
Circuit Operation:
When charging the handset on the Base Unit, the charge current is as follows;
DC+ → F1 → R39 → CHARGE+ (Base) → CHARGE+ (Handset) → Q101 → L104 → BATTERY+... Battery...
BATTERY- → R102 → 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 Q101 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) < 2.20V
The BBIC detects this level and "
• Power Down
Battery voltage: V (Batt) < 2.05V
The BBIC detects this level and power down.
4.5.

Circuit Operation (Charger Unit)

4.5.1. Power Supply Circuit
The power supply is as shown.
AC
D 1 0 7 IC103 - V D D B A T I C 1 0 3 - S D R V
L 1 0 3
2.6V.
" is displayed on LCD and "battery alarm" starts ringing.
F1
J1
AC Adaptor
R 1 0 7
I C 1 0 1 3 . 3 V
R1
11
KX-TG1711MEB/KX-TG1712MEB/KX-TGA171MEB
TP2
5.5 V DC
TP1