El Driver Ic - LG MG810c Service Manual

J. Keypad back-light Illumination
The EL backlight is controlled by KEY_BACKLIGHT signal from GPIO_0 of DBB. The EL backlight will
be turned on when the port 3 of EL driver 'D381B' goes to HIGH and the 'D381B' drives over 200 Volt
to the EL_EN signal. The EL backlight will be turned off when the port 3 of the 'D381B' goes to LOW.
KEY_BACKLIGHT
K. LCD back-light Illumination
The charge pump is controlled by high-speed mode I2C interface which is connected to the DBB. The
white LED driver provides constant-current drive for 1 to 6 backlight LEDs connected in parallel and 1
torch/strobe LED. We use only 4 white LEDs in LCD Module. The charge pump automatically switches
between 1x mode, 1.5x boost mode, and 2x boost mode on response to battery voltage, LED drive
current, and VF(LED forward bias voltage drop) conditions in order to extend battery drive life. The
SM8150AB-G operating mode settings are accessed using an I2C interface, allowing LED drive
current, 2 LDO voltage, output ON/OFF, and other setting to be controlled from the DBB.
I2C_CLK
I2C_DATA

EL DRIVER IC

1
2
R537
3
4
56K
LOW EL OFF
C326 C327
HIGH EL ON
68p 10n
Figure 17. Keypad Back-light ckts
V_IO VBAT VBAT VBAT V_IO
10
VIN1
R206
10K
15
VIN2
20
VIN3
8
PGND1
17
PGND2
11
VEN
13
SCL
14
SDA
12
SBN
22
VREF
C219 C220 C221 C222 C223
1u 1u 1u 0.1u 0.1u
Figure 18. LCD Back-light driving ckts
- 31 -
3. H/W Circuit Description
VBAT
C317
0.1u
U303 D381B
8
CHF V+
7
CLF L+
6
E VOUT
5
GND L-
L301
820uH
KDZ100VW
ZD301
1V8_CAM
2V8_CAM
C215 C216
1u 1u
4
VOUT
3
DIN1
2
DIN2
1
DIN3
28
DIN4
26
DIN5
25
U203 DIN6
24
SM8150AB-G DIN7
21
LDOUT1
19
LDOUT2
18
FB
16
LX
C224
1u
EL_EN
2V8_CAM_A
FB201 FB202
VLED
MLED1
MLED2
MLED3
MLED4
C225
1u