LG MG180C Service Manual page 39

3. H/W Circuit Description
3.5.13. Keypad back-light Illumination
There are 6 Deep Blue LEDs in Main Board for Keypad Backlight and 6 Deep Blue LEDs in Upper
Board for Upper Board Backlight. Keypad Back-light is driven by 'LEDB' line from IOTA .
3.5.14. LCD Illumination
There are 2 LEDs in the LCD module for LCD backlighting. MLED and SLED is connected driver ic of
LCD module.
LCD_BACKLIGHT
VBAT
R309 R312
R307 R308 R310
200 200 200 200
LD302 LD303 LD304
LD300 LD301
LEDB
Figure 17. Keypad Back-light Scheme
LCD LED DRIVER
VBAT
10
C303
C302
4.7u
0.1u
R520 1K
R303
C305
4.7u
47K
11
Figure 18. LCD Back-light Scheme
KEY BACKLIGHT
R313 R314 R315 R316 R317
200 200 200 200 200 200
LD305 LD306 LD307 LD308 LD309
R320
10
VA305
EVL5M02200
U300 AAT3120ITP-20-T1
4
IN C1+
C301
1u
3
2
OUT C1-
C2+
1
C304
9
EN_SET 1u
12
C2-
8
D1
7
D2
6
D3
5
GND
NC
- 38 -
R300
47K
LCD_BL_IN