Keypad Back-Light Illumination; Lcd Back Light Illumination - LG KE770 Service Manual

3.9. Keypad back-light illumination

LGF_EN
R530
100K C530
1uF

3.10. LCD back light illumination

Employed the AAT2807 is a dual charge pump designed to support both the white LED backlight and
flash applications for systems operating with lithium-ion/polymer batteries. The backlight charge pump
is capable of driving up to four LEDs at a total of 60mA. The current sinks may be operated individually
or in parallel for driving higher current LEDs. To maximize power efficiency, the charge pump operates
in 1X, 1.5X, or 2X mode, where the mode of operation is automatically selected by comparing the
forward voltage of each LED with the input voltage.
LCD BACKLIGHT & CAMERA FLASH LED DRIVER
VBAT
C214
1u
FLASH_EN
LCD_BACKLIGHT
R212 R213
100K 100K
Figure 13 LCD Back light unit and Flash LED charge pump IC
VBAT
U502
1 5
STBY NC
2 6
GND BGND
3 4
VIN VOUT
BH33FB1WHFV
Figure 12 Keypad Back-light LEDs
C201
C202 C203
1u 1u
1u
4 3
VIN VOUT_FL
13
VOUT_BL
9
GND
17
PGND
5
ISINK1
16 6
EN_FLSH ISINK2
7
ISINK3
10 8
EN_SET ISINK4
U202
AAT2805IXN-4.5-T1
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3. TECHNICAL BRIEF
C531
1uF
C542 C543
NA NA
FB201
FB202
R271
0
C218 C219 C220 C221
1u 1u 27p 27p
LD504
SSC-SWTS1007
56
A C
1 2
R534
LD503
SSC-SWTS1007
56
A C
1 2
R533
R203 120
R206 120
R208 120
R210 120
MLED
LD201
LEWWH25LA
MLED1
MLED2
MLED3
C222
27p