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Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
LGE Internal Use Only
3.8 KEY BACLKLIGHT LED Interface
There are 8 snow white color LEDs on key PCB for keypad illumination. Keypad Back-light is
controlled by AD6725-ATLAS3HLITE PWM port which has a duty control function.
The output frequencies of the LIGHTx PWM output controllers are set by the Light12Period (0x2F ) and
Light3Period (0x31 ) control registers.
With fMCLK = 13 MHz, frequencies ranging from 50.781 kHz to 49.591 Hz may be specified.
fLIGHT1 = ( fMCLK / 256 ) / ( Light12Period[9:0] + 1 )
fLIGHT2 = ( fMCLK / 256 ) / ( Light12Period[9:0] + 1 )
fLIGHT3 = ( fMCLK / 256 ) / ( Light3Period[9:0] + 1 )
he output duty cycles of the PWM output controllers are set by the LightxDutyCycle[7:0] control
registers – Light1DutyCycle (0x2D ), Light2DutyCycle (0x2E) and Light3DutyCycle (0x30 ).
This model use Light3 port and Light2 port
Figure 3-8-3 GM200 key backlight LED circuit diagram
(080728)
Change the R’s value from EDLH0011901(WHITE) TO
EDLH0012504(SNOW WHITE)
R122
R121
130
130
130
R120
LD104
LD109
R126
LD110
130
7
0
1
D
T
A
B
V
6
0
0
1
_
E
D
O
I
D
_
I
N
D
LD103
LD105
130
R125
130
R128
130
R127
LD106
LD101
TWH104-HS
EDLH0012504
130
R119
LD102
2
T
H
G
I
L
K
C
A
B
_
Y
E
K
KEY_BACKLIGHT3