Lcd Backlight Illumination - LG -S310 Service Manual

3. TECHNICAL BRIEF

3.11 LCD Backlight Illumination

The RT9367C is an integrated solution for backlighting and phone camera input supply. The part contains a
charge pump white LED driver and dual low dropout linear regulators. This IC can be shut down by pulling
EN low. In the section of charge pump, The RT9367C can power up 4 white LEDs with regulated constant
current for uniform intensity. Each channel (LED1-LED4) can support up to
25mA. The part maintains highest efficiency by utilizing a x1/x1.5/x2 fractional charge pump and low
dropout current regulators. An internal 5-bit DAC is used for brightness control. Users can easily configure up
to 32-step of LED current by I2C interface. In the section of linear regulator, The RT9367C comprises a dual
channel, low noise, and low dropout regulator sourcing up to 300mA at each channel. The range of output
voltage can be configured from 1.1V to 3.3V by I2C interface. The outputs of LDO offer 3% accuracy and low
dropout voltage of 250mV @ 300mA. The LDO also provides current limiting and output short circuit thermal
folded back protection.
LCD_LED_CA1
LCD_LED_CA2
LCD_LED_CA3
VBAT
LGE Internal Use Only
VBL_LDO_2V8
NC2
15
NC1
10
VOUT
RT9367C
20
LED1
EUSY0344402
19
U600
LED2
18
LED3
17
LED4
16
C604
1u
C605
1u
[Figure 3.11-1] Circuit Diagram
VBAT
C600
2.2u
ENA
9
AVIN
13
PVIN
6
SDA
8
SCL
7
C602
R605
C603
100K
1u 2.2u
C606
1u
- 42 -
Copyright © 2010 LG Electronics. Inc. All right reserved.
VLCD1 MAX 300mA 1.1 - 3.3V
VLDO2 MAX 300mA 1.1 - 3.3V
LCD_BL_CTRL
LCD_I2C_SDA
LCD_I2C_SCL
Only for training and service purposes