Panasonic KX-WT115CE, Service Manual

Page: 10 / 64

10
KX-WT115CE
4.3.3. Charge Circuit
Circuit Operation:
When charging the handset on the Charger Unit, the charge current is as follows;
DC+pin of J1(+)
→
F1
→
R1
→
pad
→
(Handset)
→
Q4
→
D7
→
F1
→
... Battery...
BATTERY-
→
R45
→
GND
→
CHARGE-(Handset)
→
CHARGE-pad
→
DC-pin of J1(-)
In this way, the BBIC on Handset detects the fact that the battery is charged.
The charge current is controlled by switching Q9 of Handset.
4.3.4. 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) 2.35 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.
4.3.5. Speakerphone
The hands-free loudspeaker at SP+ and SP- is used to generate the ring alarm.