Key Backlight - LG CG225 Service Manual

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 .

KEY BACKLIGHT

VBAT
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_DIMCTRL1
LEDB
Figure 17. Keypad Back-light Scheme
B/L LED DRIVER
VBAT
C416
C417
0.1u
2.2u
R422 0
R410 C430 C420
47K 2.2u 2.2u
Figure 18. LCD Back-light Scheme
- 37 -
3. H/W Circuit Description
R340 20
R341 20
U401
10 4
IN C1+
C415
1u
2 3
OUT C1-
1
C2+
C418
9
1u
EN_SET
12
C2-
8
D1
7 R412
D2
6 R420
D3
11 5
GND NC
AAT3120ITP-20-T1
VA304
R421
47K
BLLED1
56
BLLED2
56