ViewSonic VP2650WB Service Manual page 28

R608
1M F
R609
1M F
R617
10K J
C610
1000P K
A-5.) Buck Converter(MCU, USB, Audio, Panel Power section)
Fig.A shows the typical Buck Converter circuit. Q2 s a switching device, and Q1, Q4 are the
totem pole which get enough ability to drive P-MOS. When the Gtae of Q2 is low level, Q2
turns on. At high level, Q2 turns off. The pulse waveform will appear at D-terminal of Q2. L1,
C5, C6, and D1 will transfer the pulse to stable DC level.
The feedback circuit is composed of two resistors R5 and R11, and feedback the DC level
1.25V with error signal. C8 is a compensation capacitor.
ViewSonic Corporation
R603
10K
D611
UF4007-LF
IC601 NCP1203P40G
1 ‧ 8
ADJ HV
D608
RSX101VA-30
2 7
FB NC
C613
C611
+
0.1U K
47U 50V
D609
3 6
RSX101VA-30
CS VCC
R623
4.7 J
4 5 K A D604
GND DRV
LL4148
D610
A K
R612
47
RSX101VA-30
R613
1K J
D605 R619
18K
LL4148
R610
18K
C609
1000P K
R607
C607
68K
680P K
D601
UF4007-LF
L611
Z45/100MHZ
A11
E5
R611
D603 D602
150 J
K A K A
LL4148 EGP10D-LF
ZD601 C606
+
47U 50V
TZMC15
Q601
G 2SK3548-01SC
A12
R615
R614 0.22
18K
N5
Fig.A
25
Confidential - Do Not Copy
D703
Y G865C15R
J
D702
Y G865C15R
J
D701
Y G865C15R
J
T601
2 9
10
R705
10
C709 C710
1000P K 1000P K
3 R706
10
1
7
5 8
540UH
R712
2K
R714
IC602
1K J
PC123FY 1J00F
R713 C716
10K 0.1U K
IC702
KA 4 31 AZT A _ NL
R
C711
+
470U 35V
R716
28K F
R715
2.61K F
VP2650wb-1