Dell 2000FP LCD Monitor Service Guide
Circuit Operation Theory
Confidential
5
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
VCC
2OUT
2DTC
2FBK
2IN-
1IN+
SCP
RFF
GND
1OUT
1DTC
1FBK
1IN-
1IN+
RT
CT
R707
R706
R712
R713
R708
R711
R710
C703
C707
C705
C706
C704
C709
C710
C708
C702
IC701
R724
R705
R723
10K
10K
47K
47K
10K
5.1K
5.1K
(SHORT)
(1206)
16V
1U
0.01U
(OPEN)
0.01U
(OPEN)
(1206)
16V
1U
(1206)
16V
1U
(1206)
16V
1U
680P
TL1451
OPEN
10K
(1%)
OPEN
VREF
VREF
VREF
Fig. 2
The TL1451AC incorporates on a single monolithic chip all the functions required in the construction of two
pulse-width modulation control circuits. Designed primarily for power supply control, the TL1451AC contains
an on-chip 2.5V regulator two error amplifiers, an adjustable oscillator, two dead-time comparators,
undervoltage lockout circuitry, and dual common-emitter output transistor circuits. The uncommitted output
transistors provide common-emitter output capability for each controller. The internal amplifiers exhibit a
common-mode voltage range from 1.04V to 1.45V. The dead-time control comparator has no offset unless
externally altered and can provide 0% to 100% dead time. The on-chip oscillator can be operated by erminating
RT and CT. During low Vcc conditions, the undervoltage lockout control circuit feature locks the outputs off
until the internal circuitry is operational.
Feed-back Circuit
R718
R719
R726
C717
1.8K
(1%)
1.1K
(1%)
(1206)
330
1/4W
50V
1200P
Fig. 3