Circuit Operations; Lcd Circuit; Reset Circuit - Panasonic KX-DT543-B Service Manual

4.2.

Circuit Operations

4.2.1.

LCD Circuit

LCD data are output from pin 66 of IC410 to LCD module.
LCD contrast is set by electronic volume in LCD module.
VCC33 (+3.3V) of the power supply voltage is pressurized about four/three times in the LCD module and used as LCD driving volt-
age (approx. 13.8V(KX-DT546) / 10.0V(KX-DT543).)
The driving voltage is observed between pin 12 (V0) and pin 13(XV0) of CN460.
The lighting of the backlight is controlled by Q460.
The power of the backlight is output from DOUT4V5 of IC410.
4.2.2.

Reset Circuit

IC410 (DCX81) is reset internally by itself when power is supplied.
Reset Signal is output from IC410 and input into IC300 (pin 1) ,CN460 (pin 5) and IC150 (pin 41).
Ope PCB
IC150
41
RESET
ASIC2
DG
Main PCB
LCD
CN460
5
/RES
3.3V
CN160
CN400
R155
ASIC_RST
10
5
C151
IC300
1
RSTN
ASIC1
C362 R423
DG DG
LCD_RS
R424
DG
7
KX-DT543/KX-DT543-B/KX-DT546/KX-DT546-B
IC410
6
EXGPIO9
5
VCC1
73
VCC2
79
VCC3
94
VCC4
DCX81
94
GPIO15
10
EXGPIO8
VCC33