Dell 2000FP - DC-DC converter

Dell 2000FP LCD Monitor Service Guide
Circuit Operation Theory
Confidential
4
DDC IC for both D-SUB and DVI
24C02 is used to support DDC2B function in both D-SUB and DVI ports. EDID data used for D-SUB and DVI
are stored in different 24C02’s respectively.
EEPROM
A 24C16 (2048 bytes) is used to store user settings, such as user timing settings, brightness/contrast, color
temperature, etc.
DC-DC converter
Buck Converter
+
+ +
D
D
D
DG
S
S
S
5
6
7
4
3
2
18
+
L703
C713
L701
D701
Q703
Q704
R714
R715
C712
Q705
R719
D703
C711
R733
R732R731
R737
OPEN
16V
100U
68U
RB060L-40
2N3904
2N3906
3.3K
22
16V
100U
SI4431DY
1.1K
(1%)
RB060L-40
16V
100U
2.7K
0
20K
GND
Fig.1
Fig.1 shows a typical Buck converter circuit. Q705 is a switching device. Q703, Q704 are a totem pole which
gets enough ability to drive P-MOS. When pin4 of Q705 is low, Q750 turns on. At high level, Q750 turns off.
So, pulse waveform will appear at D-terminal of Q705. L701,C711,C712,C713 and D701,D703 will transfer the
pulse to stable DC level.
PWM IC (TL1451)