Behavior Of Electric Power Failure; Circuit Operation (Charger Unit) - Panasonic KX-TG7841S Service Manual

KX-TG7841/KX-TG7842/KX-TG7843/KX-TG7844/KX-TG7845/KX-TG365SK/KX-TG7871/KX-TG7872/KX-TG7873/KX-TG7874/KX-TG7875/KX-TG385SK/KX-TGA680

4.10. Behavior of Electric Power Failure

In case that the power from AC adaptor is lost and lose radio waves, BBIC (IC1) turns Q11 ON since handset presumes that
base unit's power is falied.
Base unit detects that power voltage of AC adaptor +5.5V is OFF, 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
Q10, CHG terminal and Q351.
BATT+
BATT_

4.11. 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) (P.23)
AC Adaptor
The route for this is as follows: DC+pin of J1(+) → CHARGE+pad → Handset → CHARGE-pad → DC-pin of J1(-).
Handset
Power Supply
at AC failure
(Q10,Q11,Q12)
3
R45
BBIC
IC1
J1
Base Unit
CHG+
Q351
CHG-
Power Down
DET
(Q352,Q353,Q354)
(pin101-IC501)
25
VBAT
+5.5V
R351
R352
PDN_DET
TP1
TP2