Panasonic KX-TCD455GM Service Manual

EEPROM, LCD)- RF Module: IC10- PLL Oscillator- Detector- Compress/Expander- Amplifier for transmission and reception23.2. Power Supply Circuit/Reset CircuitCircuit Operation:When power on the Handset, the voltage is as follows;BATTERY(2.2 V ~ 2.6V: TP3) +4V(4V) IC10(6, 27), D20 IC1(35) IC1(37, 22, 1, 84, 61)(2.65V)The Reset signal generates IC1,C58 and 2.65V.23.3. Charge CircuitCircuit Operation:When charging the handset on the Base Unit, the charge current is as follows;DC+(5.5V ~ 6V) D4 R43, R44 L4 CHARGE+(Base) CHARGE+(Handset) Q7 F1BATTERY+ ... Battery ... BATTERY- R14 GND CHARGE-(Handset) CHARGE-(Base)GND DC-(GND)In this way, the BBIC on Handset detects the fact that the battery is charged.The charge current is controlled by switching Q7 of Handset.Refer to Fig.101 in Power Supply Circuit ().23.4. Battery Low/Power Down DetectorCircuit Operation:"Battery Low" and "Power Down" are detected by BBIC which check the voltage from battery.The detected voltage is as follows;- Battery LowBattery voltage: V(Batt) < 2.3VThe BBIC detects this level and " " starts flashing and"battery alarm" starts ringing.- Power DownBattery voltage: V(Batt) < 2.2VThe BBIC detects this level and power down.23.5. Speakerphone and Headset Jack68