LT1182/LT1183/LT1184/LT1184F
CCFL/LCD Contrast
Switching Regulators
FEATURES
s
s
s
s
s
s
s
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
s
s
s
s
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
LT1182/LT1183/LT1184/LT1184F
DESCRIPTION
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
current. An active low shutdown pin typically reduces total
supply current to 35µA 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.
ABSOLUTE
MAXIMUM
RATINGS
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
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
PACKAGE/ORDER INFORMATION
TOP VIEW
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
LCD V
C
LCD PGND
1
2
3
4
5
6
7
8
16 CCFL V
SW
15 BULB
14 BAT
13 ROYER
12 V
IN
11 FBP
10 FBN
9
LCD V
SW
ORDER PART
NUMBER
LT1182CS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 100°C/W
TOP VIEW
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
NC
NC
1
2
3
4
5
6
7
8
16 CCFL V
SW
15 BULB
14 BAT
13 NC
12 V
IN
11 REF
10 NC
9
NC
ORDER PART
NUMBER
LT1184CS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 100°C/W
Consult factory for Industrial and Military grade parts
2
U
U
W
W W
U
U
W
TOP VIEW
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
LCD V
C
LCD PGND
1
2
3
4
5
6
7
8
16 CCFL V
SW
15 BULB
14 BAT
13 ROYER
12 V
IN
11 REF
10 FB
9
LCD V
SW
ORDER PART
NUMBER
LT1183CS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 100°C/W
TOP VIEW
CCFL PGND
I
CCFL
DIO
CCFL V
C
AGND
SHUTDOWN
NC
NC
1
2
3
4
5
6
7
8
16 CCFL V
SW
15 BULB
14 BAT
13 ROYER
12 V
IN
11 REF
10 NC
9
NC
ORDER PART
NUMBER
LT1184FCS
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 100°C/W
LT1182/LT1183/LT1184/LT1184F
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.
SYMBOL
I
Q
I
SHDN
PARAMETER
Supply Current
SHUTDOWN Supply Current
SHUTDOWN Input Bias Current
SHUTDOWN Threshold Voltage
f
Switching Frequency
Measured at CCFL V
SW
and LCD V
SW
, I
SW
= 50mA,
I
CCFL
= 100µA, CCFL V
C
= Open, (LT1182) FBN = FBP =
1V, (LT1183) FB = 1V, (LT1182/LT1183) LCD V
C
= Open
Measured at CCFL V
SW
and LCD V
SW
q
CONDITIONS
LT1182/LT1183: 3V
≤
V
IN
≤
30V
LT1184/LT1184F: 3V
≤
V
IN
≤
30V
SHUTDOWN = 0V, CCFL V
C
= LCD V
C
= Open (Note 2)
SHUTDOWN = 0V, CCFL V
C
= LCD V
C
= Open
q
q
q
MIN
TYP
9
6
35
3
MAX
14
9.5
70
6
1.2
225
240
UNITS
mA
mA
µA
µA
V
kHz
kHz
%
%
V
0.6
175
0.85
200
200
85
85
70
q
160
80
75
60
DC(MAX)
BV
Maximum Switch Duty Cycle
Switch Breakdown Voltage
Switch Leakage Current
I
CCFL
Summing Voltage
Measured at CCFL V
SW
and LCD V
SW
V
SW
= 12V, Measured at CCFL V
SW
and LCD V
SW
V
SW
= 30V, Measured at CCFL V
SW
and LCD V
SW
3V
≤
V
IN
≤
30V, Measured on LT1182/LT1183
q
20
40
0.41
0.37
0.425
0.385
0.45
0.45
0.465
0.465
5
–5
q
q
q
q
q
q
µA
µA
V
V
V
V
mV
µA
µA/µA
µA/mA
V
V
V
A
%/V
µA
V
µA
A
A
Ω
mA/A
V
V
Ω
Ω
0.49
0.54
0.505
0.555
15
15
5.20
104
0.3
2.4
1.3
1.07
0.16
150
7.5
9
3.0
2.6
1.0
30
1.264
1.274
70
30
3V
≤
V
IN
≤
30V, Measured on LT1184/LT1184F
q
∆I
CCFL
Summing Voltage for
∆Input
Programming Current
CCFL V
C
Offset Sink Current
∆CCFL
V
C
Source Current for
∆I
CCFL
Programming Current
CCFL V
C
to DIO Current Servo Ratio
CCFL V
C
Low Clamp Voltage
CCFL V
C
High Clamp Voltage
CCFL V
C
Switching Threshold
CCFL High-Side Sense Servo Current
CCFL High-Side Sense Servo Current
Line Regulation
CCFL High-Side Sense Supply Current
Bulb Protect Servo Voltage
Bulb Input Bias Current
I
LIM1
V
SAT1
∆I
Q
∆I
SW1
V
REF
CCFL Switch Current Limit
CCFL Switch On-Resistance
Supply Current Increase During
CCFL Switch On-Time
Reference Voltage
Reference Output Impedance
I
CCFL
= 0µA to 100µA
CCFL V
C
= 1.5V, Positive Current Measured into Pin
I
CCFL
= 25µA, 50µA, 75µA, 100µA,
CCFL V
C
= 1.5V
DIO = 5mA out of Pin, Measure I
VC
at CCFL V
C
= 1.5V
V
BAT
– V
BULB
= Bulb Protect Servo Voltage
I
CCFL
= 100µA
CCFL V
SW
DC = 0%
I
CCFL
= 100µA, I
VC
= 0µA at CCFL V
C
= 1.5V
BAT = 5V to 30V, I
CCFL
= 100µA,
I
VC
= 0µA at CCFL V
C
= 1.5V
Current Measured into BAT and Royer Pins
I
CCFL
= 100µA, I
VC
= 0µA at CCFL V
C
= 1.5V,
Servo Voltage Measured Between BAT and Bulb Pins
I
CCFL
= 100µA, I
VC
= 0µA at CCFL V
C
= 1.5V
Duty Cycle = 50%
Duty Cycle = 75% (Note 3)
CCFL I
SW
= 1A
CCFL I
SW
= 1A
Measured at REF (Pin 11) on LT1183/LT1184/LT1184F
q
q
q
q
q
q
5
4.95
99
0.1
2.1
0.95
1.00
0.1
4.70
94
1.7
0.6
0.93
50
6.5
100
7.0
5
1.25
0.9
1.9
1.6
0.6
20
1.224
1.214
20
5
1.244
1.244
45
15
Measured at REF (Pin 11) on LT1183
Measured at REF (Pin 11) on LT1184/LT1184F
q
q
3
LT1182/LT1183/LT1184/LT1184F
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.
SYMBOL
PARAMETER
V
REF
– I
CCFL
Summing Voltage
V
REF
– I
CCFL
Summing Voltage
REF1
LCD FBP/FB Reference Voltage
REF1 Voltage Line Regulation
FBP/FB Input Bias Current
LCD FBN/FB Offset Voltage
Offset Voltage Line Regulation
FBN/FB Input Bias Current
g
m
FBP/FB to LCD V
C
Transconductance
FBN/FB to LCD V
C
Transconductance
LCD Error Amplifier Source Current
LCD Error Amplifier Sink Current
LCD V
C
Low Clamp Voltage
LCD V
C
High Clamp Voltage
LCD V
C
Switching Threshold
I
LIM2
V
SAT2
∆I
Q
∆I
SW2
LCD Switch Current Limit
LCD Switch On-Resistance
Supply Current Increase During
LCD Switch On-Time
Switch Minimum On-Time
CONDITIONS
Measured on LT1183
q
MIN
0.760
0.725
TYP
0.795
0.795
0.775
0.775
1.244
1.244
0.01
0.35
MAX
0.830
0.865
0.810
0.845
1.264
1.274
0.03
1.0
–4
–1
0.2
UNITS
V
V
V
V
V
V
%/V
µA
mV
mV
%/V
µA
Measured on LT1184/LT1184F
LT1182: Measured at FBP Pin, FBN = 1V, LCD V
C
= 0.8V
LT1183: Measured at FB Pin, LCD V
C
= 0.8V
3V
≤
V
IN
≤
30V, LCD V
C
= 0.8V
LT1182: FBP = REF1, FBN = 1V, LCD V
C
= 0.8V
LT1183: FB = REF1, LCD V
C
= 0.8V
LT1182: Measured at FBN Pin, FBP = 0V, LCD V
C
= 0.8V
LT1183: Measured at FB Pin, LCD V
C
= 0.8V
3V
≤
V
IN
≤
30V, LCD V
C
= 0.8V
LT1182: FBN = Offset Voltage, FBP = 0V, LCD V
C
= 0.8V
LT1183: FB = Offset Voltage, LCD V
C
= 0.8V
LT1182:
∆I
VC
=
±25µA,
FBN = 1V
LT1183:
∆I
VC
=
±25µA
LT1182:
∆I
VC
=
±25µA,
FBP = GND
LT1183:
∆I
VC
=
±25µA
LT1182: FBP = FBN = 1V or 0.25V,
LT1183: FB = 1V or 0.25V
LT1182: FBP = FBN = 1.5V or – 0.25V,
LT1183: FB = 1.5V or – 0.25V
LT1182: FBP = FBN = 1.5V, LT1183: FB = 1.5V
LT1182: FBP = FBN = 1V, LT1183: FB = 1V
LT1182: FBP = FBN = 1V, LT1183: FB = 1V, V
SW
DC = 0%
Duty Cycle = 50%
Duty Cycle = 75% (Note 3)
LCD I
SW
= 0.5A
LCD I
SW
= 0.5A
Measured at CCFL V
SW
and LCD V
SW
0.740
q
0.705
1.224
q
1.214
q
q
q
q
q
q
q
q
q
– 20
– 27
– 12
– 12
0.01
– 3.0
650
500
550
400
50
35
– 1.0
900
900
800
800
100
100
0.01
1150
1300
1050
1200
175
175
0.3
2.4
1.3
1.5
1.3
1.65
30
µmhos
µmhos
µmhos
µmhos
µA
µA
V
V
V
A
A
Ω
mA/A
µs
1.7
0.6
q
q
q
2.0
0.95
1.00
0.85
1.0
20
0.45
0.625
0.400
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.
4
LT1182/LT1183/LT1184/LT1184F
TYPICAL PERFORMANCE CHARACTERISTICS
LT1182/LT1183 Supply Current
vs Temperature
14
13
SHUTDOWN CURRENT (µA)
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
12
11
10
9
8
7
6
5
4
–75 – 50 – 25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 G01
V
IN
= 30V
V
IN
= 3V
Shutdown Input Bias Current
vs Temperature
6
1.2
SHUTDOWN INPUT BIAS CURRENT (µA)
SHUTDOWN THRESHOLD VOLTAGE (V)
5
4
V
IN
= 30V
3
2
1
0
–75 –50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 G04
1.0
0.9
0.8
0.7
0.6
–75 –50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 G05
CCFL FREQUENCY (kHz)
V
IN
= 5V
V
IN
= 3V
CCFL Duty Cycle vs Temperature
95
93
91
240
230
CCFL DUTY CYCLE (%)
LCD FREQUENCY (kHz)
89
87
85
83
81
79
77
75
–75 – 50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 • G07
LCD DUTY CYCLE (%)
U W
LT1184/LT1184F Supply Current
vs Temperature
10
9
8
7
6
5
4
3
2
1
0
–75 – 50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 G02
Shutdown Current
vs Temperature
100
90
8O
70
60
50
40
30
20
10
0
–75 – 50 – 25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 G03
V
IN
= 30V
V
IN
= 30V
V
IN
= 3V
V
IN
= 5V
V
IN
= 3V
Shutdown Threshold Voltage
vs Temperature
240
230
220
210
200
190
180
170
CCFL Frequency vs Temperature
1.1
V
IN
= 30V
V
IN
= 3V
160
–75 –50 –25
0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 • G06
LCD Frequency vs Temperature
95
93
91
220
210
200
190
180
170
160
–75 – 50 –25
0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 • G08
LCD Duty Cycle vs Temperature
89
87
85
83
81
79
77
75
–75 – 50 –25 0 25 50 75 100 125 150 175
TEMPERATURE (°C)
LT1182 • G09
V
IN
= 30V
V
IN
= 3V
5
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