Circuit Operation (Handset) - Panasonic KX-TG234SK Service Manual

KX-TG234SK/KX-TGA470B
4.7.

Circuit Operation (Handset)

4.7.1. 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)
4.7.2. 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 → BBC1 (IC1) 10 pin
The Reset signal generates IC1 (54 pin) and 1.8 V.
VBAT
External Charge Pump
VBAT
VDDC (1.2 V)
Reset (RSTN)
(IC1_54 pin)
Startmonitor
(IC1 57pin)
(CKM/STM)
VBAT
BATTERY
2CELL
GND
VDDC (1.2V)
4.0V
Circuit or IC
4.0 output
BBIC chip initialize
3.0V 3.0V
DOUBLER OUT (Charge Pump)
For all peripherals
3.0V 3.0V
BBIC
3.0V
BELL, KEY LED
GND
20
3.0V 3.0V
EEPROM
LCD
4.0V
LCD BACKLIT LED
GND