Panasonic KX-TDA0103XJ, Service Manual

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8.1.1.4. Battery Voltage Input/Output
This section explains about the operation of Battery Voltage Input/Output.
1) While Outputting the Battery Voltage (While charging)
During normal operation FETs Q153 and Q155 of battery Input/Output DC switching circuit are ON and connected to the main
converter to output the regulated main converter output voltage.
When the battery switch SW501 is turned ON and CN102 is shorted between pin 3 and 4, the voltage is fed from main converter
output to the controller circuit. Transistors Q503 and Q504 of battery controller circuit are turned ON. n-BATT output signal
output becomes LOW. And also transistor Q505 is turned ON, the voltage from T301 (Sub winding) is fed to the gate of Q153
and Q155, and then Q153 and Q155 turn ON. On the other hand, when the battery switch SW501 is turned OFF, Q503 and
Q504 are turned OFF, n-BATT output signal output becomes OPEN.
When over current flows to battery output, the voltage difference occurs at detection resistors R172, R191 and R192. Q154
becomes ON and Q153 becomes OFF.
Consequently the fold back current limiting shuts down battery output.
Refer to Fig. 4 (A), (B).
2) While Battery Voltage is being Input (At the time of the power failure)
The battery voltage is passed through FET Q155 and diode D157, and then fed to main converter output (C401, C402 and
C403).
When battery voltage is decreased, Q503, Q504 and Q505 of battery controller circuit become OFF, and Q155 of battery
input/output DC switch circuit is turned OFF.
Consequently the battery is cut, and power supply is stopped.
Refer to Fig. 4 (A), (B).
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KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X