LT1182/LT1183/LT1184/LT1184F
CCFL/LCD Contrast
Switching Regulators
FEATURES
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DESCRIPTION
The LT
®
1182/LT1183 are dual current mode switching
regulators that provide the control function for Cold Cath-
ode Fluorescent Lighting (CCFL) and Liquid Crystal Display
(LCD) Contrast. The LT1184/LT1184F provide only the
CCFL function. The ICs include high current, high efficiency
switches, an oscillator, a reference, output drive logic,
control blocks and protection circuitry. The LT1182 per-
mits positive or negative voltage LCD contrast operation.
The LT1183 permits unipolar contrast operation and pins
out an internal reference. The LT1182/LT1183 support
grounded and floating lamp configurations. The LT1184F
supports grounded and floating lamp configurations. The
LT1184 supports only grounded lamp configurations. The
, LTC and LT are registered trademarks of Linear Technology Corporation.
Wide Input Voltage Range: 3V to 30V
Low Quiescent Current
High Switching Frequency: 200kHz
CCFL Switch : 1.25A, LCD Switch: 625mA
Grounded or Floating Lamp Configurations
Open-Lamp Protection
Positive or Negative Contrast Capability
APPLICATIONS
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Notebook and Palmtop Computers
Portable Instruments
Automotive Displays
Retail Terminals
TYPICAL APPLICATION
90% Efficient Floating CCFL Configuration with Dual Polarity LCD Contrast
UP TO 6mA
ALUMINUM ELECTROLYTIC IS RECOMMENDED FOR C3B WITH AN
ESR
≥
0.5Ω TO PREVENT DAMAGE TO THE LT1182 HIGH-SIDE
SENSE RESISTOR DUE TO SURGE CURRENTS AT TURN-ON.
C1 MUST BE A LOW LOSS CAPACITOR, C1 = WIMA MKP-20
Q1, Q2 = ZETEX ZTX849 OR ROHM 2SC5001
L1 = COILTRONICS CTX210605
L2 = COILTRONICS CTX100-4
L3 = COILTRONICS CTX02-12403
*DO
NOT SUBSTITUTE COMPONENTS
COILTRONICS (407) 241-7876
0µA TO 45µA ICCFL
CURRENT GIVES
0mA TO 6mA
BULB CURRENT.
THIS IS EQUAL TO
0% TO 90% DUTY
CYCLE FOR THE
PWM SIGNAL.
R4
46.4k
1%
C6
2.2µF
C5
1000pF
R2
220k
3
2
1
C3B
2.2µF
35V
R1
750Ω
4
5
LAMP
10
6
C2
27pF
3kV
L1
CCFL BACKLIGHT APPLICATION CIRCUITS CONTAINED IN THIS
DATA SHEET ARE COVERED BY U.S. PATENT NUMBER 5408162
AND OTHER PATENTS PENDING
+
+
C1*
0.068µF
R3
100k
D5
BAT85
L2
100µH
1
D1
1N5818
+
Q1*
Q2*
D3
1N5934A
4
24V
D2
2
1N914
V (PWM)
0V TO 5V
1kHz PWM
R5, 43.2k, 1%
CCFL
PGND
I
CCFL
DIO
CCFL V
SW
BULB
BAT
16
15
14
2
3
+
C7, 1µF
4
5
SHUTDOWN
6
C8, 0.68µF
7
R7, 10K 8
LT1182
13
CCFL V
C
ROYER
AGND
SHDN
LCD V
C
LCD
PGND
V
IN
FBP
FBN
LCD V
SW
12
11
+
C4
2.2µF
C9, 0.01µF
10
9
R9, 4.99k, 1%
5V
R10, 10k, 1%
R11, 20k, 1%
C10
0.01µF
U
U
U
C3A
2.2µF
35V
BAT
8V TO 28V
EITHER NEGCON OR POSCON
MUST BE GROUNDED.
GROUNDING NEGCON GIVES
VARIABLE POSITIVE CONTRAST
FROM 10V TO 30V.
GROUNDING POSCON GIVES
VARIABLE NEGATIVE CONTRAST
FROM –10V TO – 30V.
L3
6
9
N = 1:2
C11
22µF
35V
POSCON
C12
2.2µF
35V
+
NEGCON
D4
1N914
R12
20k
R13
8.45k
1%
R14
1.21k
1%
V
IN
≥
3V
1182/3 TA01
1
LINER [ LINEAR TECHNOLOGY ]
