1
LT1182/LT1183/LT1184/LT1184F
CCFL/LCD Contrast
Switching Regulators
s
Wide Input Voltage Range: 3V to 30V
s
Low Quiescent Current
s
High Switching Frequency: 200kHz
s
CCFL Switch : 1.25A, LCD Switch: 625mA
s
Grounded or Floating Lamp Configurations
s
Open-Lamp Protection
s
Positive or Negative Contrast Capability
FEATURES
DESCRIPTIO
N
U
APPLICATIO
N
S
U
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
s
Notebook and Palmtop Computers
s
Portable Instruments
s
Automotive Displays
s
Retail Terminals
90% Efficient Floating CCFL Configuration with Dual Polarity LCD Contrast
TYPICAL APPLICATIO
N
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
C12
2.2
F
35V
BAT
8V TO 28V
POSCON
NEGCON
1182/3 TA01
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.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
I
CCFL
DIO
CCFL V
C
AGND
SHDN
LCD V
C
CCFL V
SW
BULB
BAT
ROYER
V
IN
FBP
FBN
LCD V
SW
CCFL
PGND
LCD
PGND
LT1182
LAMP
UP TO 6mA
10
6
L1
L3
R1
750
L2
100
H
3
2
1
5
4
+
+
+
ALUMINUM ELECTROLYTIC IS RECOMMENDED FOR C3B WITH AN
ESR
0.5
TO PREVENT DAMAGE TO THE LT1182 HIGH-SIDE
SENSE RESISTOR DUE TO SURGE CURRENTS AT TURN-ON.
C7, 1
F
C1*
0.068
F
D1
1N5818
D2
1N914
D4
1N914
V (PWM)
0V TO 5V
1kHz PWM
SHUTDOWN
C8, 0.68
F
R7, 10K
C5
1000pF
R2
220k
R3
100k
C3A
2.2
F
35V
C11
22
F
35V
R13
8.45k
1%
R14
1.21k
1%
5V
R10, 10k, 1%
R9, 4.99k, 1%
C4
2.2
F
V
IN
3V
D3
1N5934A
24V
C3B
2.2
F
35V
C2
27pF
3kV
+
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
Q2*
Q1*
N = 1:2
0
A TO 45
A ICCFL
CURRENT GIVES
0mA TO 6mA
BULB CURRENT.
THIS IS EQUAL TO
0% TO 90% DUTY
CYCLE FOR THE
PWM SIGNAL.
R12
20k
R5, 43.2k, 1%
C6
2.2
F
R4
46.4k
1%
+
D5
BAT85
C10
0.01
F
R11, 20k, 1%
C9, 0.01
F
2
4
6
9
+
CCFL BACKLIGHT APPLICATION CIRCUITS CONTAINED IN THIS
DATA SHEET ARE COVERED BY U.S. PATENT NUMBER 5408162
AND OTHER PATENTS PENDING
2
LT1182/LT1183/LT1184/LT1184F
DESCRIPTIO
N
U
current. An active low shutdown pin typically reduces total
supply current to 35
A for standby operation. A 200kHz
switching frequency minimizes the size of required mag-
netic components. The use of current mode switching
techniques with cycle-by-cycle limiting gives high reliabil-
ity and simple loop frequency compensation. The LT1182/
LT1183/LT1184/LT1184F are all available in 16-pin nar-
row SO packages.
LT1184/LT1184F pin out the reference for simplified pro-
gramming of lamp current.
The LT1182/LT1183/LT1184/LT1184F operate with input
supply voltages from 3V to 30V. The ICs also have a
battery supply voltage pin that operates from 4.5V to 30V.
The LT1182/LT1183 draw 9mA typical quiescent current
while the LT1184/LT1184F draw 6mA typical quiescent
V
IN
, BAT, Royer, Bulb .............................................. 30V
CCFL V
SW
, LCD V
SW
............................................... 60V
Shutdown ................................................................. 6V
I
CCFL
Input Current .............................................. 10mA
DIO Input Current (Peak, < 100ms) .................... 100mA
LT1182: FBP, FBN, LT1183: FB Pin Current .........
2mA
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
T
JMAX
= 100
C,
JA
= 100
C/W
T
JMAX
= 100
C,
JA
= 100
C/W
Consult factory for Industrial and Military grade parts
LT1183CS
ORDER PART
NUMBER
T
JMAX
= 100
C,
JA
= 100
C/W
T
JMAX
= 100
C,
JA
= 100
C/W
LT1182CS
ORDER PART
NUMBER
LT1184CS
ORDER PART
NUMBER
LT1184FCS
LT1183/LT1184/1184F: REF Pin Source Current .... 1mA
Junction Temperature (Note 1) ............................ 100
C
Operating Ambient Temperature Range ..... 0
C to 100
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec) .................. 300
C
ORDER PART
NUMBER
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
LCD V
C
LCD PGND
CCFL V
SW
BULB
BAT
ROYER
V
IN
FBP
FBN
LCD V
SW
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
NC
NC
CCFL V
SW
BULB
BAT
NC
V
IN
REF
NC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
LCD V
C
LCD PGND
CCFL V
SW
BULB
BAT
ROYER
V
IN
REF
FB
LCD V
SW
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
NC
NC
CCFL V
SW
BULB
BAT
ROYER
V
IN
REF
NC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
3
LT1182/LT1183/LT1184/LT1184F
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Supply Current
LT1182/LT1183: 3V
V
IN
30V
q
9
14
mA
LT1184/LT1184F: 3V
V
IN
30V
q
6
9.5
mA
I
SHDN
SHUTDOWN Supply Current
SHUTDOWN = 0V, CCFL V
C
= LCD V
C
= Open (Note 2)
35
70
A
SHUTDOWN Input Bias Current
SHUTDOWN = 0V, CCFL V
C
= LCD V
C
= Open
3
6
A
SHUTDOWN Threshold Voltage
q
0.6
0.85
1.2
V
f
Switching Frequency
Measured at CCFL V
SW
and LCD V
SW
, I
SW
= 50mA,
175
200
225
kHz
I
CCFL
= 100
A, CCFL V
C
= Open, (LT1182) FBN = FBP =
1V, (LT1183) FB = 1V, (LT1182/LT1183) LCD V
C
= Open
q
160
200
240
kHz
DC(MAX)
Maximum Switch Duty Cycle
Measured at CCFL V
SW
and LCD V
SW
80
85
%
q
75
85
%
BV
Switch Breakdown Voltage
Measured at CCFL V
SW
and LCD V
SW
60
70
V
Switch Leakage Current
V
SW
= 12V, Measured at CCFL V
SW
and LCD V
SW
20
A
V
SW
= 30V, Measured at CCFL V
SW
and LCD V
SW
40
A
I
CCFL
Summing Voltage
3V
V
IN
30V, Measured on LT1182/LT1183
0.41
0.45
0.49
V
q
0.37
0.45
0.54
V
3V
V
IN
30V, Measured on LT1184/LT1184F
0.425
0.465
0.505
V
q
0.385
0.465
0.555
V
I
CCFL
Summing Voltage for
I
CCFL
= 0
A to 100
A
5
15
mV
Input Programming Current
CCFL V
C
Offset Sink Current
CCFL V
C
= 1.5V, Positive Current Measured into Pin
5
5
15
A
CCFL V
C
Source Current for
I
CCFL
= 25
A, 50
A, 75
A, 100
A,
q
4.70
4.95
5.20
A/
A
I
CCFL
Programming Current
CCFL V
C
= 1.5V
CCFL V
C
to DIO Current Servo Ratio
DIO = 5mA out of Pin, Measure I
VC
at CCFL V
C
= 1.5V
q
94
99
104
A/mA
CCFL V
C
Low Clamp Voltage
V
BAT
V
BULB
= Bulb Protect Servo Voltage
q
0.1
0.3
V
CCFL V
C
High Clamp Voltage
I
CCFL
= 100
A
q
1.7
2.1
2.4
V
CCFL V
C
Switching Threshold
CCFL V
SW
DC = 0%
q
0.6
0.95
1.3
V
CCFL High-Side Sense Servo Current
I
CCFL
= 100
A, I
VC
= 0
A at CCFL V
C
= 1.5V
q
0.93
1.00
1.07
A
CCFL High-Side Sense Servo Current
BAT = 5V to 30V, I
CCFL
= 100
A,
0.1
0.16
%/V
Line Regulation
I
VC
= 0
A at CCFL V
C
= 1.5V
CCFL High-Side Sense Supply Current
Current Measured into BAT and Royer Pins
q
50
100
150
A
Bulb Protect Servo Voltage
I
CCFL
= 100
A, I
VC
= 0
A at CCFL V
C
= 1.5V,
q
6.5
7.0
7.5
V
Servo Voltage Measured Between BAT and Bulb Pins
Bulb Input Bias Current
I
CCFL
= 100
A, I
VC
= 0
A at CCFL V
C
= 1.5V
5
9
A
I
LIM1
CCFL Switch Current Limit
Duty Cycle = 50%
q
1.25
1.9
3.0
A
Duty Cycle = 75% (Note 3)
q
0.9
1.6
2.6
A
V
SAT1
CCFL Switch On-Resistance
CCFL I
SW
= 1A
q
0.6
1.0
I
Q
Supply Current Increase During
CCFL I
SW
= 1A
20
30
mA/A
I
SW1
CCFL Switch On-Time
V
REF
Reference Voltage
Measured at REF (Pin 11) on LT1183/LT1184/LT1184F
1.224
1.244
1.264
V
q
1.214
1.244
1.274
V
Reference Output Impedance
Measured at REF (Pin 11) on LT1183
q
20
45
70
Measured at REF (Pin 11) on LT1184/LT1184F
q
5
15
30
ELECTRICAL CHARACTERISTICS
T
A
= 25
C, V
IN
= 5V, BAT = Royer = Bulb = 12V, I
CCFL
= SHUTDOWN = CCFL V
SW
= Open, DIO = GND, CCFL V
C
= 0.5V,
(LT1182/LT1183) LCD V
C
= 0.5V, LCD V
SW
= Open, (LT1182) FBN = FBP = GND, (LT1183) FB = GND,
(LT1183/LT1184/LT1184F) REF = Open, unless otherwise specified.
4
LT1182/LT1183/LT1184/LT1184F
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
REF
I
CCFL
Summing Voltage
Measured on LT1183
0.760
0.795
0.830
V
q
0.725
0.795
0.865
V
V
REF
I
CCFL
Summing Voltage
Measured on LT1184/LT1184F
0.740
0.775
0.810
V
q
0.705
0.775
0.845
V
REF1
LCD FBP/FB Reference Voltage
LT1182: Measured at FBP Pin, FBN = 1V, LCD V
C
= 0.8V
1.224
1.244
1.264
V
LT1183: Measured at FB Pin, LCD V
C
= 0.8V
q
1.214
1.244
1.274
V
REF1 Voltage Line Regulation
3V
V
IN
30V, LCD V
C
= 0.8V
q
0.01
0.03
%/V
FBP/FB Input Bias Current
LT1182: FBP = REF1, FBN = 1V, LCD V
C
= 0.8V
LT1183: FB = REF1, LCD V
C
= 0.8V
q
0.35
1.0
A
LCD FBN/FB Offset Voltage
LT1182: Measured at FBN Pin, FBP = 0V, LCD V
C
= 0.8V
20
12
4
mV
LT1183: Measured at FB Pin, LCD V
C
= 0.8V
q
27
12
1
mV
Offset Voltage Line Regulation
3V
V
IN
30V, LCD V
C
= 0.8V
q
0.01
0.2
%/V
FBN/FB Input Bias Current
LT1182: FBN = Offset Voltage, FBP = 0V, LCD V
C
= 0.8V
LT1183: FB = Offset Voltage, LCD V
C
= 0.8V
q
3.0
1.0
A
g
m
FBP/FB to LCD V
C
Transconductance
LT1182:
I
VC
=
25
A, FBN = 1V
650
900
1150
mhos
LT1183:
I
VC
=
25
A
q
500
900
1300
mhos
FBN/FB to LCD V
C
Transconductance
LT1182:
I
VC
=
25
A, FBP = GND
550
800
1050
mhos
LT1183:
I
VC
=
25
A
q
400
800
1200
mhos
LCD Error Amplifier Source Current
LT1182: FBP = FBN = 1V or 0.25V,
q
50
100
175
A
LT1183: FB = 1V or 0.25V
LCD Error Amplifier Sink Current
LT1182: FBP = FBN = 1.5V or 0.25V,
q
35
100
175
A
LT1183: FB = 1.5V or 0.25V
LCD V
C
Low Clamp Voltage
LT1182: FBP = FBN = 1.5V, LT1183: FB = 1.5V
0.01
0.3
V
LCD V
C
High Clamp Voltage
LT1182: FBP = FBN = 1V, LT1183: FB = 1V
1.7
2.0
2.4
V
LCD V
C
Switching Threshold
LT1182: FBP = FBN = 1V, LT1183: FB = 1V, V
SW
DC = 0%
0.6
0.95
1.3
V
I
LIM2
LCD Switch Current Limit
Duty Cycle = 50%
q
0.625
1.00
1.5
A
Duty Cycle = 75% (Note 3)
q
0.400
0.85
1.3
A
V
SAT2
LCD Switch On-Resistance
LCD I
SW
= 0.5A
q
1.0
1.65
I
Q
Supply Current Increase During
LCD I
SW
= 0.5A
20
30
mA/A
I
SW2
LCD Switch On-Time
Switch Minimum On-Time
Measured at CCFL V
SW
and LCD V
SW
0.45
s
T
A
= 25
C, V
IN
= 5V, BAT = Royer = Bulb = 12V, I
CCFL
= SHUTDOWN = CCFL V
SW
= Open, DIO = GND, CCFL V
C
= 0.5V,
(LT1182/LT1183) LCD V
C
= 0.5V, LCD V
SW
= Open, (LT1182) FBN = FBP = GND, (LT1183) FB = GND,
(LT1183/LT1184/LT1184F) REF = Open, unless otherwise specified.
The
q
denotes specifications which apply over the specified operating
temperature range.
Note 1: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LT1182CS/LT1183CS/LT1184CS/LT1184FCS: T
J
= T
A
+ (P
D
100
C/W)
Note 2: Does not include switch leakage.
Note 3: For duty cycles (DC) between 50% and 75%, minimum
guaranteed switch current is given by I
LIM
= 1.4(1.393 DC) for the CCFL
regulator and I
LIM
= 0.7(1.393 DC ) for the LCD contrast regulator due to
internal slope compensation circuitry.
5
LT1182/LT1183/LT1184/LT1184F
TEMPERATURE (
C)
75
LCD DUTY CYCLE (%)
87
91
95
93
89
85
81
77
125 150
LT1182 G09
83
79
75
25 0
50
25 50
75 100
175
TEMPERATURE (
C)
75
CCFL DUTY CYCLE (%)
87
91
95
93
89
85
81
77
125 150
LT1182 G07
83
79
75
25 0
50
25 50
75 100
175
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
LT1184/LT1184F Supply Current
vs Temperature
LT1182/LT1183 Supply Current
vs Temperature
Shutdown Input Bias Current
vs Temperature
TEMPERATURE (
C)
0
SHUTDOWN INPUT BIAS CURRENT (
A)
2
4
6
5
3
1
25
25
75
125
LT1182 G04
175
50
75
0
50
100
150
V
IN
= 5V
V
IN
= 3V
V
IN
= 30V
Shutdown Threshold Voltage
vs Temperature
TEMPERATURE (
C)
0.6
SHUTDOWN THRESHOLD VOLTAGE (V)
0.8
1.0
1.2
1.1
0.9
0.7
25
25
75
125
LT1182 G05
175
50
75
0
50
100
150
TEMPERATURE (
C)
75
CCFL FREQUENCY (kHz)
220
240
125
LT1182 G06
200
180
160
25
25
75
175
210
230
190
170
100
50
0
50
150
V
IN
= 30V
V
IN
= 3V
CCFL Frequency vs Temperature
LCD Duty Cycle vs Temperature
LCD Frequency vs Temperature
CCFL Duty Cycle vs Temperature
Shutdown Current
vs Temperature
TEMPERATURE (
C)
75
SUPPLY CURRENT (mA)
10
12
14
13
11
9
7
5
125
LT1182 G01
8
6
4
25
50
0
50
100
150
25
75
175
V
IN
= 30V
V
IN
= 3V
TEMPERATURE (
C)
75
SHUTDOWN CURRENT (
A)
60
8O
100
90
70
50
30
10
125
LT1182 G03
40
20
0
25
50
0
50
100
150
25
75
175
V
IN
= 30V
V
IN
= 5V
V
IN
= 3V
TEMPERATURE (
C)
75
SUPPLY CURRENT (mA)
6
8
10
9
7
5
3
1
125
LT1182 G02
4
2
0
25
50
0
50
100
150
25
75
175
V
IN
= 30V
V
IN
= 3V
TEMPERATURE (
C)
75
LCD FREQUENCY (kHz)
220
240
125
LT1182 G08
200
180
160
25
25
75
175
210
230
190
170
100
50
0
50
150
V
IN
= 3V
V
IN
= 30V
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