MP1039 – FULL BRIDGE CCFL CONTROLLER
OPERATION
V
PS
R1
R8
1
3
SI
VIN2
22
1.2V
LV
TG2 24
BT2 23
SW2 25
BG2 27
FAULT
LEVEL
SHIFT
C10
C11
C8
MANAGEMENT
1.2V
C2
6
2
FT
R
LI
LI
LI
ERROR
AMP
12 ABRT
C1
R3
PGND2
28
26
4
COMP
LAMP
PWM
VCC2
7
8
SWSET
SWPLL
LAMP
CLOCK
R4
C4
V
PS
C12
R9
VIN1
15
C3
ABRT
LSYNC
EN
TG1 17
14 LSYNC
10 BRS
LEVEL
SHIFT
C13
C14
BT1
SW1
BG1
16
18
20
21
19
R6
C7
DBRT
C5
R5
C6
BURST
RATE
GENERATOR
9
BRPLL
PGND1
VCC1
C9
R2
13 ENSYNC
11 DBRT
SI LV
LI
BURST
PWM
5
AGND
Figure 1—MP1039 Block Diagram
The MP1039 implements burst mode dimming
of the lamp and features soft-on-soft-off control
of the lamp current envelope that is virtually
independent of supply voltage.
DESIGN INFORMATION
The MP1039 is a fixed operating frequency
inverter controller specifically designed to drive
a cold cathode fluorescent lamp (CCFL) used
as a backlight for liquid crystal displays.
Designed to run off 10V to 28V input supplies,
the MP1039 can drive up to 20 lamps (140W)
via four (4) external N-Channel MOSFETs. Its
full bridge architecture converts unregulated DC
input voltages to the nearly pure sine waves
required to ignite and operate CCFLs. The
Operating frequency is set by an external resistor
to minimize the possibility of interference with the
refresh rate of the display.
Burst frequency and duty cycle can either be
determined by driving the MP1039 with an
external logic signal or by choosing an external
resistor and capacitor to set the burst rate and
modulating the duty cycle with a DC control
voltage on DBRT.
Loop gain is compensated for variations in
supply voltage and the full-wave lamp current
sense amplifier provides superior output pulse
symmetry, loop response time, and phase
margin.
Regulated lamp current and maximum peak
transformer secondary current are set by
external resistors. Regulated open lamp voltage
is set by an external capacitive voltage divider.
The switching frequency of the MP1039 is set
by an external resistor. This frequency can be
synchronized to the input clock signal at the
LSYNC pin.
MP1039 Rev. 1.1
9/24/2007
www.MonolithicPower.com
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© 2007 MPS. All Rights Reserved.
6
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