KX-TG6621RUB, KX-TG6621RUM, KX-TG6621UAB, KX-TG6621UAM, KX-TG6621CAB, KX-TG6621CAM, KX-TG6622CAB, KX-TGA661RUB, KX-TGA661RUM - Panasonic Telephone Service Manual (repair manual). Page 13

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KX-TG6621RU/KX-TG6621UA/KX-TG6621CA/KX-TG6622CA/KX-TGA661RU
4.5.
Circuit Operation (Charger Unit)
4.5.1.
Power Supply Circuit
The power supply is as shown.
4.6.
Behavior of Electric Power Failure
In case that the power from AC adaptor is lost and lose radio waves, BBIC (IC1) turns IC6 ON since handset presumes that
base unit's power is failed.
Base unit detects that power voltage of AC adaptor +5.5V 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 IC7,
CHG terminal and Q351.
R1
TP1
TP2
J1
AC Adaptor
F1
IC7
Handset
BATT+
BATT_
Base Unit
Q351
VBAT
IC351
VIN
VOUT
COUT
BBIC
IC1
R45
CHG-
CHG+
D1
R354
R355
R351
R352
3
VOUT
VIN
VSS
+5.5V
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