Circuit Operation (Handset); Outline; Power Supply Circuit/Reset Circuit - Panasonic KX-TG7841S Service Manual

KX-TG7841/KX-TG7842/KX-TG7843/KX-TG7844/KX-TG7845/KX-TG365SK/KX-TG7871/KX-TG7872/KX-TG7873/KX-TG7874/KX-TG7875/KX-TG385SK/KX-TGA680
4.9.

Circuit Operation (Handset)

4.9.1.

Outline

Handset consists of the following ICs as shown in Block Diagram (Handset) (P.21).
• 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)
4.9.2.

Power Supply Circuit/Reset Circuit

Circuit Operation:
When powering 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)
Start monitor
(IC1 57pin)
(CKM/STM)
VBAT
BATTERY
2CELL
GND
VDDC (1.2V)
4.0V
Circuit or IC
4.0 output
LCD BACKLIT LED
BBIC chip initialize
3.0V 3.0V
DOUBLER OUT (Charge Pump)
For all peripherals
3.0V 3.0V
BBIC
3.0V
KEY LED
GND
23
3.0V 3.0V
EEPROM
LCD