
22
KX-TG3721BX/KX-TG3722BX/KX-TGA371BX
4.9.
Behavior of Electric Power Failure
In case that the power from AC adaptor is lost and lose radio waves, BBIC (IC1) turns Q11 and Q10 ON since handset
presumes that base unit's power is failed.
Base unit detects that power voltage of AC a5.5V is OFF at IC351, then turns Q351 ON.
It's possible to use the units during the power failure, supplying power to VBAT of base unit from battery of handset through IC6,
CHG terminal and Q351.
4.10. Circuit Operation (Charger Unit)
Charge control is executed at handset side so that the operation when using charger is also controlled by handset.
Refer to
Circuit Operation (Handset)
The route for this is as follows: DC+pin of J1(+)
→
F1
→
R1
→
pad
→
Handset
→
CHARGE-pad
→
DC-pin of J1(-).
BATT+
Q10
Q12
Q11
R11
R14
R13
R6
BATT_
Base Unit
Handset
Q351
VBAT
IC351
BBIC
IC1
R45
CHG-
CHG+
R354
R355
R351
R352
71
VOUT
VIN
VSS
+5.5V
GND GND
R1
TP1 (pad)
TP2 (CHARGE- pad)
J1
AC Adaptor
F1
(+)
(-)