Circuit Operation (Handset) - Panasonic KX-TG3721BXB Service Manual

KX-TG3721BX/KX-TG3722BX/KX-TGA371BX
4.8.

Circuit Operation (Handset)

4.8.1. Outline
Handset consists of the following ICs as shown in Block Diagram (Handset) (P.18).
• DECT BBIC (Base Band IC): IC1
- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, EEPROM, LCD)
• EEPROM: IC3
- Setting data is stored. (e.g. ID, user setting)
4.8.2. Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Handset, the voltage is as follows;
BATTERY(2.2 V ~ 2.6 V: BATT+) → F1 → BBIC (IC1) 41 pin
The Reset signal generates IC1 (62 pin) and 1.8 V.
BATTERY
2CELL
GND
VBAT
1.8 V
Reset (RSTN)
(IC1_62 pin)
VBAT
1.8V
BBIC
3.0V
GND
2.8V
3.0V 3.0V
DOUBLER OUT (Charge Pump)
For all peripherals
2.8V
VBAT
KEY BACKLIGHT
LCD BACKLIGHT
LED
20
2.8V
EEPROM
LCD
BELL, LED