LG GW520 - Keypad Back-Light Illumination

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
3. BB Circuit Technical brief
GW520 service manual
3.10 keypad back-light illumination
3.10.1 Qwerty keypad back-light illumination
There are 2 snow white color LEDs on Key for keypad illumination. Keypad Back-light is controlled by SM-
Power3 Flash LED port which has constant current control function. The whole configuration of the SM-
POWER3 Flash LED drivers is shown in below Figure.
[Figure 3.10.1-1] LED driver in the SM-POWER3
[Figure 3.10.1-2] Qwerty key back-light LED circuit diagram
47R442
LD403
LEWWS44-E
47R445
ICVN0505X150FR
VA403
VBAT
R444 47
R439
LD402
47
LD401
LEWWS44-E
LEWWS44-E
LD400
EDLH0013701
LEWWS44-E
QWERTY_KEY_BL