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LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. Circuit Description
4.2.13 SIGNAL CONTROL PATH FOR BACKLIGHT LED, CAMERA FLASH
LED AND INDICATOR LED
4.2.13.1 Backlight LED Control
The LCD backlight is controlled by the PWL signal from the MTK6226. The backlight is turned on when
PWM1_LCM_EN is high. The LCD backlight a 5V power supply. The RT9396 DC/DC converter (U801)
generates the singal for LED1,LED2 ,LED3 Detailed circuit diagram is as shown below.
LED3
LED2
LED1
VDD
VBAT
LPA0
P.4
LWRB
P.4
LRDB
P.4
NLD0
P.4
NLD1
P.4
NLD2
P.4
NLD3
P.4
NLD4
P.4
NLD5
P.4
NLD6
P.4
NLD7
P.4
LCM_MAIN_CS P.4
LRSTB
P.4
GPIO18_LCM_ID P.4
C806
33pF_5%
0402C-S
C808
33pF_5%
0508
1
3
5
7
8
6
4
2
J801
1.77"_QQVGA
LCM-ARIMA-1.77-QQVGA-11
D3
9
D4
8
D5
7
D6
6
D7
5
RESET
4
VDD (2.8V)
3
NC
2
ID (LOW)
1
D2
10
D1
11
D0
12
RD
13
WR
14
RS
15
CS
16
K3
17
K2
18
K1
19
A1
20
GND
21
GND
22
C801
100nF_10%
0402C-S
C809
33pF_5%
0508
1
3
5
7
8
6
4
2
C807
33pF_5%
0508
1
3
5
7
8
6
4
2
LED1
LED2
LED3
VBAT
PWM1_LCM_EN
P.4
C804
100pF_5%
0402C-S
C805
1uF_10%_10V
0402C-S
C803
1uF_10%_16V
0603C-S
U801
RT9363
RT9363
VOUT
2
VIN
4
EN
6
CP
5
LED1
7
LED2
8
LED3
1
GND
3
R801
10K_5%
0402R-S
C802
4.7uF_10%_6.3V
0603C-S