ViewSonic VA703b Service Manual page 70

11.2 Power
U701 SOT-223
+5V
NC/LT1117-18
3 2
VI VO
4
VO
C701
NC 100uF/25V
BL_ADJ(DC) R31
0V ~ 3.3V 4.7K
0V ~ 5V 4.7K
BL_ADJ R31 C32
P W M 47 N.C
D C 4K7 1uF
+12V
+12V 4
CN701
C706 C707
GND
1 2
+
0.1uF GND 3 4
100uF/25V +12V 5 6
GND
+5V 7 8
+5V 9 10
3,4 +5V
GND 11 12
C710 CONN
C709
+
VCC5V
0.1uF 100uF/25V
R701
1K
R706 NC
Q701
Adj_BACKLIGHT
PMBS3904
R707
4.7K 1/16W
+3V3 +3V3
+5V
R714
R716 R717
10K 1/16W
10K 1/16W
NC
R723 51K
R725
Q706
4 on_Panel
4.7K 1/16W
PMBS3904
C718
0.1uF
ViewSonic Corporation
+3V3
+3V3
9
C703 C704
+
NC
C51 R32 R29 R33 Q4
1UF 0 X X X
1UF X 1K 4.7K MMBT3904
+5V
R708
+5V
10K 1/16W
BL_ON R710 NC
BL_ADJ
+12V
GND C711
+5V R712 4.7K 1/16W
GND 0.1uF
Q703
PMBS3904
D704(SSM12L) Vf=0.38V and If=1A.
So when system power on, the
1/16W
system loading is about 400mA
R705 4.7K
1/16W
(3.3V is about 200mA and 1.8V is
about 200mA), So D35 changed
from 1N4148(or BAT42) to
C708
SSM12L(schottky diode).
1uF
P.S: The 1N4148 Vf=0.7V~1V can't meet
LDO spec. The BAT42, Vf is OK but the
If=200mA(forward current) can not
meet current spec.
For RSDS and Panel VCC=12V
VLCD
VLCD 5
+5V +3V3
R715
NC
R721 R722
Q704
1/16W AO3401L 0 1/16W NC
C715
4 on_Panel_12V
0.1uF C717 R727
+
10uF/16V 10K 1/16W
Confidential - Do Not Cop
H1 H2 H3
5 9 5 9 5
9 5 9 5 9 5
4 4 4
4 4 4
TP TP TP
R711
10K 1/16W
on_BACKLIGHT 4 3,4 +5V
+5V
3,4 +5V
D704
SMAL140
+5V
+5V +12V VLCD_12V
VLCD_12V 5
R718 R729 R719
NC/10K NC/10K NC/10K
Q705
R724 51K AO3401L
R726 NC/4K7 C716
Q707
0.1uF
PMBS3904
C720 C719 R728
+
NC/0.1uF NC/10uF/16V NC/4K7
- 70 –
VA703b/VA703m
VCTRL
R702
51 1/16W
C702
+
4.7uF/16V
D701
1N4148
B R703
Q702
2K 1/16W
D702 CHT2907
1N4148
C705
1uF/16V R704
100 1/16W VCC3.3
+5V PC5V
Recommond to used "Blue" parts circuit
for VCC1.8V if you want to suppoert DDC
PC5V 3
function when system power off
R732 R709
10 1/16W 0 1/16W
D703
TO-263
BAT54C
U702
3 2
VIN VOUT
4
VOUT
1
ADJ
R713 C712
C713 AIC1084-33PM
+
NC
0.1uF 100uF/25V
R720 0 1/16W
12/21 MODIFY
+5V +12V
R730
R731
0 1/16W NC
Title
TSUM16AK
Size Document Number
B
POWER
Date: Monday, May 09, 2005
4
VCC1.8
VCC1.8 4
VCC3.3 4
VCC3.3
VCC3.3 4
C714
0.1uF
Rev
A
Sheet 1 of 5