Panasonic KX-TG3721BXB Service Manual page 13

4.5.5. Power Supply Circuit/Reset Circuit
The power supply voltage from AC adaptor is converted to VBAT (3.0V) in IC302. And +3.0V for peripherals and analog part is
insulated from VBAT by Doubler of BBIC.
Circuit Operation:
+5.5V
+5.5V
AC Adaptor
+3.0V
IC302
3.0V
REGULATOR
+3.0V
+1.8V
Reset (RSTN)
(IC501_77pin)
VDD3
IC501
+3.0V
VDD1
BBIC
+1.8V
Q301
VDD2
+2.4V
Q302
RF Part
LEDs
13
KX-TG3721BX/KX-TG3722BX/KX-TGA371BX
VDD4
IC502
+3.0V_CP
QSPI FLASH
VDD5
IC601
+3.0V_CP2
TAM FLASH
IC611
EEPROM