LT1184CS#PBF [Linear]
LT1184 - CCFL/LCD Contrast Switching Regulators; Package: SO; Pins: 16; Temperature Range: 0°C to 70°C;
| 型号： | LT1184CS#PBF |
| 厂家： | 
Linear |
| 描述： | LT1184 - CCFL/LCD Contrast Switching Regulators; Package: SO; Pins: 16; Temperature Range: 0°C to 70°C 稳压器 开关 CD |
| 文件： | 总24页 (文件大小：408K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1182/LT1183/LT1184/LT1184F
CCFL/LCD Contrast
Switching Regulators
U
FEATURES
DESCRIPTION
The LT®1182/LT1183 are dual current mode switching
regulators that provide the control function for Cold Cath-
odeFluorescentLighting(CCFL)andLiquidCrystalDisplay
(LCD) Contrast. The LT1184/LT1184F provide only the
CCFLfunction.TheICsincludehighcurrent,highefficiency
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
U
APPLICATIONS
■
Notebook and Palmtop Computers
■
Portable Instruments
■
Automotive Displays
Retail Terminals
■
U
TYPICAL APPLICATION
90% Efficient Floating CCFL Configuration with Dual Polarity LCD Contrast
UP TO 6mA
LAMP
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.
CCFL BACKLIGHT APPLICATION CIRCUITS CONTAINED IN THIS
DATA SHEET ARE COVERED BY U.S. PATENT NUMBER 5408162
AND OTHER PATENTS PENDING
C2
27pF
3kV
10
6
C1 MUST BE A LOW LOSS CAPACITOR, C1 = WIMA MKP-20
Q1, Q2 = ZETEX ZTX849 OR ROHM 2SC5001
L1 = COILTRONICS CTX210605
L1
3
2
1
5
4
BAT
8V TO 28V
L2 = COILTRONICS CTX100-4
+
C3B
+
+
C3A
2.2µF
35V
2.2µF
L3 = COILTRONICS CTX02-12403
*DO NOT SUBSTITUTE COMPONENTS
COILTRONICS (407) 241-7876
C5
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.
R2
35V
1000pF
220k
R1
C1*
0.068µF
750Ω
0µA TO 45µA ICCFL
CURRENT GIVES
0mA TO 6mA
BULB CURRENT.
THIS IS EQUAL TO
0% TO 90% DUTY
C12
2.2µF
35V
R3
100k
Q2*
Q1*
POSCON
D5
D3
L3
BAT85
CYCLE FOR THE
PWM SIGNAL.
1N5934A
24V
6
9
C11 +
22µF
L2
100µH
4
D1
1N5818
35V
D2
1N914
R4
1
2
3
4
5
6
7
8
16
2
CCFL
PGND
CCFL V
46.4k
SW
R5, 43.2k, 1%
V (PWM)
0V TO 5V
1kHz PWM
1%
NEGCON
15
14
13
12
11
10
9
I
BULB
BAT
N = 1:2
CCFL
D4
1N914
+
C6
2.2µF
DIO
C7, 1µF
R12
20k
LT1182
C
V
IN
≥ 3V
CCFL V
AGND
SHDN
ROYER
+
C4
2.2µF
R13
8.45k
1%
V
IN
SHUTDOWN
FBP
FBN
C8, 0.68µF
C9, 0.01µF
R14
1.21k
1%
C10
0.01µF
LCD V
LCD
C
R7, 10K
LCD V
SW
PGND
R11, 20k, 1%
R9, 4.99k, 1%
R10, 10k, 1%
5V
1182/3 TA01
1
LT1182/LT1183/LT1184/LT1184F
U
DESCRIPTION
LT1184/LT1184F pin out the reference for simplified pro-
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.
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
W W U W
ABSOLUTE MAXIMUM RATINGS
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
VIN, BAT, Royer, Bulb .............................................. 30V
CCFL VSW, LCD VSW ............................................... 60V
Shutdown ................................................................. 6V
ICCFL Input Current .............................................. 10mA
DIO Input Current (Peak, < 100ms) .................... 100mA
LT1182: FBP, FBN, LT1183: FB Pin Current......... ±2mA
U
W U
PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW
ORDER PART
ORDER PART
CCFL V
CCFL V
BULB
BAT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CCFL PGND
CCFL PGND
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
SW
SW
NUMBER
NUMBER
BULB
BAT
I
I
CCFL
CCFL
DIO
DIO
LT1182CS
LT1183CS
ROYER
ROYER
CCFL V
C
CCFL V
C
V
V
AGND
AGND
IN
IN
FBP
REF
FB
SHUTDOWN
SHUTDOWN
FBN
LCD V
C
LCD V
C
LCD V
LCD V
LCD PGND
LCD PGND
SW
SW
S PACKAGE
16-LEAD PLASTIC SO
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX = 100°C, θJA = 100°C/W
TJMAX = 100°C, θJA = 100°C/W
TOP VIEW
TOP VIEW
ORDER PART
NUMBER
ORDER PART
NUMBER
CCFL V
CCFL V
BULB
BAT
CCFL PGND
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
CCFL PGND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SW
SW
BULB
BAT
NC
I
I
CCFL
CCFL
DIO
DIO
LT1184FCS
LT1184CS
ROYER
CCFL V
C
CCFL V
C
V
V
AGND
SHUTDOWN
NC
AGND
SHUTDOWN
NC
IN
IN
REF
NC
REF
NC
NC
NC
NC
NC
S PACKAGE
16-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 100°C/W
S PACKAGE
16-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 100°C/W
Consult factory for Industrial and Military grade parts
2
LT1182/LT1183/LT1184/LT1184F
ELECTRICAL CHARACTERISTICS
TA = 25°C, VIN = 5V, BAT = Royer = Bulb = 12V, ICCFL = SHUTDOWN = CCFL VSW = Open, DIO = GND, CCFL VC = 0.5V,
(LT1182/LT1183) LCD VC = 0.5V, LCD VSW = Open, (LT1182) FBN = FBP = GND, (LT1183) FB = GND,
(LT1183/LT1184/LT1184F) REF = Open, unless otherwise specified.
SYMBOL PARAMETER
CONDITIONS
LT1182/LT1183: 3V ≤ V ≤ 30V
MIN
TYP
MAX
UNITS
I
Supply Current
●
●
9
6
14
9.5
mA
mA
Q
IN
LT1184/LT1184F: 3V ≤ V ≤ 30V
IN
I
SHUTDOWN Supply Current
SHUTDOWN Input Bias Current
SHUTDOWN Threshold Voltage
Switching Frequency
SHUTDOWN = 0V, CCFL V = LCD V = Open (Note 2)
35
3
70
6
µA
µA
V
SHDN
C
C
SHUTDOWN = 0V, CCFL V = LCD V = Open
C
C
●
0.6
0.85
200
1.2
225
f
Measured at CCFL V and LCD V , I = 50mA,
175
kHz
SW
SW SW
I
= 100µA, CCFL V = Open, (LT1182) FBN = FBP =
CCFL
C
1V, (LT1183) FB = 1V, (LT1182/LT1183) LCD V = Open
●
●
160
200
240
kHz
C
DC(MAX) Maximum Switch Duty Cycle
Measured at CCFL V and LCD V
80
75
85
85
%
%
SW
SW
BV
Switch Breakdown Voltage
Switch Leakage Current
Measured at CCFL V and LCD V
60
70
V
SW
SW
V
SW
V
SW
= 12V, Measured at CCFL V and LCD V
20
40
µA
µA
SW
SW
SW
= 30V, Measured at CCFL V and LCD V
SW
I
Summing Voltage
3V ≤ V ≤ 30V, Measured on LT1182/LT1183
0.41
0.37
0.45
0.45
0.49
0.54
V
V
CCFL
IN
●
●
3V ≤ V ≤ 30V, Measured on LT1184/LT1184F
0.425
0.385
0.465 0.505
0.465 0.555
V
V
IN
∆I
Summing Voltage for
I
= 0µA to 100µA
CCFL
5
15
mV
CCFL
∆Input Programming Current
CCFL V Offset Sink Current
CCFL V = 1.5V, Positive Current Measured into Pin
–5
5
15
µA
C
C
∆CCFL V Source Current for
I
= 25µA, 50µA, 75µA, 100µA,
CCFL
●
4.70
4.95
5.20
µA/µA
C
∆I
Programming Current
CCFL V = 1.5V
CCFL
C
CCFL V to DIO Current Servo Ratio
DIO = 5mA out of Pin, Measure I at CCFL V = 1.5V
●
●
●
●
●
94
99
0.1
104
0.3
µA/mA
C
VC
C
CCFL V Low Clamp Voltage
V
BAT
– V = Bulb Protect Servo Voltage
BULB
V
V
C
CCFL V High Clamp Voltage
I
= 100µA
1.7
0.6
2.1
2.4
C
CCFL
CCFL V Switching Threshold
CCFL V DC = 0%
0.95
1.00
0.1
1.3
V
C
SW
CCFL High-Side Sense Servo Current
I
= 100µA, I = 0µA at CCFL V = 1.5V
0.93
1.07
0.16
A
CCFL
VC
C
CCFL High-Side Sense Servo Current
Line Regulation
BAT = 5V to 30V, I
= 100µA,
%/V
CCFL
I
= 0µA at CCFL V = 1.5V
VC
C
CCFL High-Side Sense Supply Current Current Measured into BAT and Royer Pins
●
●
50
100
7.0
150
7.5
µA
Bulb Protect Servo Voltage
I
= 100µA, I = 0µA at CCFL V = 1.5V,
6.5
V
CCFL
VC
C
Servo Voltage Measured Between BAT and Bulb Pins
Bulb Input Bias Current
I
= 100µA, I = 0µA at CCFL V = 1.5V
5
9
µA
CCFL
VC
C
I
CCFL Switch Current Limit
Duty Cycle = 50%
Duty Cycle = 75% (Note 3)
●
●
1.25
0.9
1.9
1.6
3.0
2.6
A
A
LIM1
V
CCFL Switch On-Resistance
CCFL I = 1A
●
0.6
20
1.0
30
Ω
SAT1
SW
∆I
∆I
Supply Current Increase During
CCFL Switch On-Time
CCFL I = 1A
mA/A
Q
SW
SW1
V
REF
Reference Voltage
Measured at REF (Pin 11) on LT1183/LT1184/LT1184F
1.224
1.214
1.244 1.264
1.244 1.274
V
V
●
Reference Output Impedance
Measured at REF (Pin 11) on LT1183
Measured at REF (Pin 11) on LT1184/LT1184F
●
●
20
5
45
15
70
30
Ω
Ω
3
LT1182/LT1183/LT1184/LT1184F
ELECTRICAL CHARACTERISTICS
TA = 25°C, VIN = 5V, BAT = Royer = Bulb = 12V, ICCFL = SHUTDOWN = CCFL VSW = Open, DIO = GND, CCFL VC = 0.5V,
(LT1182/LT1183) LCD VC = 0.5V, LCD VSW = Open, (LT1182) FBN = FBP = GND, (LT1183) FB = GND,
(LT1183/LT1184/LT1184F) REF = Open, unless otherwise specified.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
– I
Summing Voltage
Measured on LT1183
0.760
0.725
0.795 0.830
0.795 0.865
V
V
REF
CCFL
●
●
V
– I
CCFL
Summing Voltage
Measured on LT1184/LT1184F
0.740
0.705
0.775 0.810
0.775 0.845
V
V
REF
REF1
LCD FBP/FB Reference Voltage
LT1182: Measured at FBP Pin, FBN = 1V, LCD V = 0.8V
1.224
1.214
1.244 1.264
1.244 1.274
V
V
C
LT1183: Measured at FB Pin, LCD V = 0.8V
●
●
C
REF1 Voltage Line Regulation
FBP/FB Input Bias Current
3V ≤ V ≤ 30V, LCD V = 0.8V
0.01
0.03
%/V
IN
C
LT1182: FBP = REF1, FBN = 1V, LCD V = 0.8V
C
LT1183: FB = REF1, LCD V = 0.8V
●
0.35
1.0
µA
C
LCD FBN/FB Offset Voltage
LT1182: Measured at FBN Pin, FBP = 0V, LCD V = 0.8V
–20
–27
–12
–12
–4
–1
mV
mV
C
LT1183: Measured at FB Pin, LCD V = 0.8V
●
●
C
Offset Voltage Line Regulation
FBN/FB Input Bias Current
3V ≤ V ≤ 30V, LCD V = 0.8V
0.01
0.2
%/V
IN
C
LT1182: FBN = Offset Voltage, FBP = 0V, LCD V = 0.8V
C
LT1183: FB = Offset Voltage, LCD V = 0.8V
●
●
–3.0
– 1.0
µA
C
g
FBP/FB to LCD V Transconductance
LT1182: ∆I = ±25µA, FBN = 1V
650
500
900
900
1150
1300
µmhos
µmhos
m
C
VC
LT1183: ∆I = ±25µA
VC
FBN/FB to LCD V Transconductance
LT1182: ∆I = ±25µA, FBP = GND
550
400
800
800
1050
1200
µmhos
µmhos
C
VC
LT1183: ∆I = ±25µA
●
●
VC
LCD Error Amplifier Source Current
LCD Error Amplifier Sink Current
LT1182: FBP = FBN = 1V or 0.25V,
LT1183: FB = 1V or 0.25V
50
100
175
µA
LT1182: FBP = FBN = 1.5V or –0.25V,
LT1183: FB = 1.5V or –0.25V
●
35
100
175
µA
LCD V Low Clamp Voltage
LT1182: FBP = FBN = 1.5V, LT1183: FB = 1.5V
LT1182: FBP = FBN = 1V, LT1183: FB = 1V
0.01
2.0
0.3
2.4
1.3
V
V
V
C
LCD V High Clamp Voltage
1.7
0.6
C
LCD V Switching Threshold
LT1182: FBP = FBN = 1V, LT1183: FB = 1V, V DC = 0%
0.95
C
SW
I
LCD Switch Current Limit
Duty Cycle = 50%
Duty Cycle = 75% (Note 3)
●
●
0.625
0.400
1.00
0.85
1.5
1.3
A
A
LIM2
V
LCD Switch On-Resistance
LCD I = 0.5A
●
1.0
20
1.65
30
Ω
SAT2
SW
∆I
∆I
Supply Current Increase During
LCD Switch On-Time
LCD I = 0.5A
mA/A
Q
SW
SW2
Switch Minimum On-Time
Measured at CCFL V and LCD V
0.45
µs
SW
SW
The
●
denotes specifications which apply over the specified operating
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 = 1.4(1.393 – DC) for the CCFL
temperature range.
Note 1: T is calculated from the ambient temperature T and power
J
A
LIM
dissipation P according to the following formula:
regulator and I = 0.7(1.393 – DC ) for the LCD contrast regulator due to
internal slope compensation circuitry.
D
LIM
LT1182CS/LT1183CS/LT1184CS/LT1184FCS: T = T + (P × 100°C/W)
J
A
D
4
LT1182/LT1183/LT1184/LT1184F
TYPICAL PERFORMANCE CHARACTERISTICS
W
U
LT1182/LT1183 Supply Current
vs Temperature
LT1184/LT1184F Supply Current
vs Temperature
Shutdown Current
vs Temperature
10
9
8
7
6
5
4
3
2
1
0
100
90
8O
70
60
50
40
30
20
10
0
14
13
12
11
10
9
V
IN
= 30V
V
V
= 30V
= 3V
IN
V
IN
= 30V
IN
V
= 3V
IN
V
= 5V
= 3V
IN
8
7
V
IN
6
5
4
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 G02
LT1182 G03
LT1182 G01
Shutdown Input Bias Current
vs Temperature
Shutdown Threshold Voltage
vs Temperature
CCFL Frequency vs Temperature
240
230
220
210
200
190
180
170
160
6
5
1.2
1.1
4
3
2
1
0
1.0
0.9
0.8
0.7
0.6
V
IN
= 30V
V
= 5V
IN
V
= 30V
IN
V
IN
= 3V
V
= 3V
IN
–75
–50 –25
0
25 50 75 100
125
150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G06
LT1182 G04
LT1182 G05
CCFL Duty Cycle vs Temperature
LCD Frequency vs Temperature
LCD Duty Cycle vs Temperature
95
93
91
89
240
230
220
210
200
190
180
170
160
95
93
91
89
V
= 30V
IN
87
85
87
85
V
= 3V
IN
83
81
79
77
75
83
81
79
77
75
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G07
LT1182 • G08
LT1182 • G09
5
LT1182/LT1183/LT1184/LT1184F
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
ICCFL Summing Voltage
vs Temperature
ICCFL Summing Voltage
Load Regulation
CCFL VC Offset Sink Current
vs Temperature
10
0.53
0.52
0.51
0.50
0.49
0.48
0.47
0.46
0.45
0.44
0.43
0.42
0.41
0.40
0.39
0.38
5
4
3
2
1
9
8
7
6
5
CCFL V = 1.5V
C
T = –55°C
T = 25°C
0
CCFL V = 1.0V
C
V
IN
= 30V
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
V
= 5V
IN
4
3
2
V
= 3V
IN
T = 125°C
1
0
–1
–2
–3
CCFL V = 0.5V
C
–75 –50 –25
0
25 50 75 100 125 150 175
0
20 40 60 80 100 120 140 160 180 200
PROGRAMMING CURRENT (µA)
–75 – 50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
I
TEMPERATURE (°C)
CCFL
LT1182 • G12
LT1182 • G10
LT1182 • G11
∆CCFL VC Source Current for
∆ICCFL Programming Current
vs Temperature
Positive DIO Voltage
vs Temperature
Negative DIO Voltage
vs Temperature
1.2
1.0
0.8
0.6
0.4
0.2
0
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
5.10
5.05
5.00
4.95
4.90
4.85
4.80
I(DIO) = 10mA
I(DIO) = 5mA
I(DIO) = 1mA
I(DIO) = 10mA
I(DIO) = 1mA
I
= 100µA
CCFL
I(DIO) = 5mA
I
= 50µA
CCFL
I
= 10µA
CCFL
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G13
LT1182 • G14
LT1182 • G15
CCFL VC Low Clamp Voltage
vs Temperature
CCFL VC High Clamp Voltage
vs Temperature
CCFL VC to DIO Current Servo
Ratio vs Temperature
103
102
101
100
99
0.30
0.25
0.20
0.15
0.10
0.05
0
2.4
2.3
I(DIO) = 10mA
I(DIO) = 1mA
2.2
2.1
2.0
1.9
1.8
I(DIO) = 5mA
98
97
96
95
1.7
–75 – 50–25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75
0
50 75 100 125 150 175
– 50 –25
25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G16
LT1182 • G17
LT1182 • G18
6
LT1182/LT1183/LT1184/LT1184F
TYPICAL PERFORMANCE CHARACTERISTICS
W
U
CCFL VC Switching Threshold
Voltage vs Temperature
LCD VC Low Clamp Voltage
vs Temperature
LCD VC High Clamp Voltage
vs Temperature
1.00
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.10
0
1.3
1.2
2.4
2.3
1.1
2.2
1.0
0.9
0.8
0.7
2.1
2.0
1.9
1.8
0.6
1.7
–75
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–75
0
50 75 100 125 150 175
–75
0
50 75 100 125 150 175
– 50 –25
25
– 50 –25
25
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G20
LT1182 • G19
LT1182 • G21
LCD VC Switching Threshold
Voltage vs Temperature
CCFL High-Side Sense Null
Current vs Temperature
CCFL High-Side Sense Null Current
Line Regulation vs Temperature
0.160
0.140
0.120
0.100
0.080
0.060
0.040
0.020
0.000
1.060
1.040
1.020
1.000
0.980
0.960
0.940
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
–75 –50 –25
0
25 50 75 100 125 150 175
–75 – 50–25
0
25 50 75 100 125 150 175
–75
0
50 75 100 125 150 175
–50 –25
25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G23
LT1182 • G24
LT1182 • G22
CCFL High-Side Sense Supply
Current vs Temperature
Bulb Protect Servo Voltage
vs Temperature
Bulb Input Bias Current
vs Temperature
150
140
130
120
7.5
7.4
7.3
7.2
10
8
I
= 100µA
CCFL
6
110
100
7.1
7.0
90
80
70
60
50
6.9
6.8
6.7
6.6
6.5
4
2
0
I
= 50µA
CCFL
I
= 10µA
CCFL
–75 –50 –25
0
25 50 75 100 125 150 175
–50
–25
–75
–75 – 50 –25
0
25 50 75 100 125 150 175
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G25
LT1182 • G26
LT1182 • G27
7
LT1182/LT1183/LT1184/LT1184F
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
LCD FBP Reference
vs Temperature
FBP Reference Voltage Line
Regulation vs Temperature
FBP Input Bias Current
vs Temperature
1.274
1.264
1.254
1.244
1.234
1.224
1.214
0.03
0.025
0.020
0.015
0.010
0.005
0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
–75 – 50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
–75 – 50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G28
LT1182 • G29
LT1182 • G30
LCD FBN Offset Voltage
vs Temperature
FBN Input Bias Current
vs Temperature
FBP to LCD VC Transconductance
vs Temperature
1300
1200
1100
1000
900
–1
3.0
2.5
2.0
1.5
1.0
0.5
0
–3
–5
–7
–9
–11
–13
–15
–17
–19
–21
–23
–25
–27
800
700
600
500
–75 –50 –25
0
25 50 75 100 125 150 175
–75 – 50–25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G32
LT1182 • G33
FBN to LCD VC Transconductance
vs Temperature
LT1184/84F REF Output
Impedance vs Temperature
LT1183 REF Output Impedance
vs Temperature
1200
1100
1000
900
70
65
60
55
50
45
30
25
20
800
40
35
30
25
20
15
10
5
700
600
500
400
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
75 100 125 150 175
25 50
–75 – 50–25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1182 • G35
LT1182 • G36
LT1182 • G34
8
LT1182/LT1183/LT1184/LT1184F
TYPICAL PERFORMANCE CHARACTERISTICS
W
U
LCD VSW Sat Voltage
vs Switch Current
CCFL VSW Sat Voltage
vs Switch Current
CCFL VSW Current Limit
vs Duty Cycle
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.0
1.6
1.2
0.8
0.4
0
2.5
2.0
T = 25°C
T = 0°C
T = 25°C
T = 125°C
MINIMUM
T = 125°C
T = –5°C
1.5
T = 25°C
T = –5°C
T = 125°C
1.0
0.5
0
0
0.3
0.6
0.9
1.2
1.5
0
0.3
0.6
0.9
1.2
1.5
0
10 20 30 40 50 60 70 80 90
DUTY CYCLE (%)
SWITCH CURRENT (A)
SWITCH CURRENT (A)
LT1182 • G37
LT1182 • G38
LT1182 • G39
LCD VSW Current Limit
vs Duty Cycle
Forced Beta vs ISW on CCFL VSW
Forced Beta vs ISW on LCD VSW
110
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
1.5
1.2
0.9
T = 25°C
T = 125°C
MINIMUM
T = 0°C
0.6
0.3
0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0
10 20 30 40 50 60 70 80 90
DUTY CYCLE (%)
LCD I (A)
SW
CCFL I (A)
SW
LT1182 • G42
LT1182 • G41
LT1182 • G40
9
LT1182/LT1183/LT1184/LT1184F
U
U
U
PIN FUNCTIONS
LT1182/LT1183/LT1184/LT1184F
tor for the CCFL regulator. Its uses include frequency
compensation,lamp-currentaveragingforgroundedlamp
circuits, and current limiting. The voltage on the CCFL VC
pin determines the current trip level for switch turnoff.
During normal operation this pin sits at a voltage between
0.95V (zero switch current) and 2.0V (maximum switch
current) with respect to analog ground (AGND). This pin
has a high impedance output and permits external voltage
clamping to adjust current limit. A single capacitor to
ground provides stable loop compensation. This simpli-
fied loop compensation method permits the CCFL regula-
tor to exhibit single-pole transient response behavior and
virtually eliminates transformer output overshoot.
CCFL PGND (Pin 1): This pin is the emitter of an internal
NPN power switch. CCFL switch current flows through
this pin and permits internal, switch-current sensing. The
regulators provide a separate analog ground and power
ground(s) to isolate high current ground paths from low
current signal paths. Linear Technology recommends the
use of star-ground layout techniques.
ICCFL (Pin2):ThispinistheinputtotheCCFLlampcurrent
programmingcircuit.Thispininternallyregulatesto450mV
(LT1182/LT1183) or 465mV (LT1184/LT1184F). The pin
accepts a DC input current signal of 0µA to 100µA full
scale. This input signal is converted to a 0µA to 500µA
source current at the CCFL VC pin. By shunt regulating the
ICCFL pin, the input programming current can be set with
DAC, PWM or potentiometer control. As input program-
ming current increases, the regulated lamp current in-
creases. For a typical 6mA lamp, the range of input
programming current is about 0µA to 50µA.
AGND (Pin 5): This pin is the low current analog ground.
It is the negative sense terminal for the internal 1.24V
reference and the ICCFL summing voltage in the LT1182/
LT1183/LT1184/LT1184F. It is also a sense terminal for
the LCD dual input error amplifier in the LT1182/LT1183.
Connectexternalfeedbackdividernetworksthatterminate
to ground and frequency compensation components that
terminate to ground directly to this pin for best regulation
and performance.
DIO (Pin 3): This pin is the common connection between
the cathode and anode of two internal diodes. The remain-
ing terminals of the two diodes connect to ground. In a
grounded lamp configuration, DIO connects to the low
voltage side of the lamp. Bidirectional lamp current flows
in the DIO pin and thus the diodes conduct alternately on
half cycles. Lamp current is controlled by monitoring one-
half of the average lamp current. The diode conducting on
negativehalfcycleshasone-tenthofitscurrentdivertedto
the CCFL VC pin. This current nulls against the source
current provided by the lamp-current programmer circuit.
A single capacitor on the CCFL VC pin provides both stable
loop compensation and an averaging function to the half-
wave-rectified sinusoidal lamp current. Therefore, input
programming current relates to one-half of average lamp
current. This scheme reduces the number of loop com-
pensation components and permits faster loop transient
response in comparison to previously published circuits.
If a floating-lamp configuration is used, ground the DIO
pin.
SHUTDOWN (Pin 6): Pulling this pin low causes complete
regulator shutdown with quiescent current typically re-
duced to 35µA. The nominal threshold voltage for this pin
is 0.85V. If the pin is not used, it can float high or be pulled
to a logic high level (maximum of 6V). Carefully evaluate
active operation when allowing the pin to float high.
Capacitive coupling into the pin from switching transients
could cause erratic operation.
CCFL VSW (Pin 16): This pin is the collector of the internal
NPN power switch for the CCFL regulator. The power
switch provides a minimum of 1.25A. Maximum switch
current is a function of duty cycle as internal slope com-
pensation ensures stability with duty cycles greater than
50%. Using a driver loop to automatically adapt base drive
current to the minimum required to keep the switch in a
quasi-saturationstateyieldsfastswitchingtimesandhigh
efficiency operation. The ratio of switch current to driver
current is about 50:1.
CCFL VC (Pin 4): This pin is the output of the lamp current
programmer circuit and the input of the current compara-
10
LT1182/LT1183/LT1184/LT1184F
U
U
U
PIN FUNCTIONS
Bulb (Pin 15): This pin connects to the low side of a 7V
threshold comparator between the BAT and Bulb pins.
This circuit sets the maximum voltage level across the
primary side of the Royer converter under all operating
conditions and limits the maximum secondary output
under start-up conditions or open lamp conditions. This
eases transformer voltage rating requirements. Set the
voltagelimittoinsurelampstart-upwithworst-case,lamp
start voltages and cold-temperature system operating
conditions. The Bulb pin connects to the junction of an
external divider network. The divider network connects
from the center tap of the Royer transformer or the actual
battery supply voltage to the top side of the current source
“tail inductor”. A capacitor across the top of the divider
network filters switching ripple and sets a time constant
that determines how quickly the clamp activates. When
the comparator activates, sink current is generated to pull
the CCFL VC pin down. This action transfers the entire
regulator loop from current mode operation into voltage
mode operation.
Royer (Pin 13): This pin connects to the center-tapped
primary of the Royer converter and is used with the BAT
pin in a floating lamp configuration where lamp current is
controlled by sensing Royer primary side converter cur-
rent. This pin is the inverting terminal of a high-side
current sense amplifier. The typical quiescent current is
50µA into the pin. If the CCFL regulator is not used in a
floating lamp configuration, tie the Royer and BAT pins
together. ThispinisonlyavailableontheLT1182/LT1183/
LT1184F.
VIN (Pin 12): This pin is the supply pin for the LT1182/
LT1183/LT1184/LT1184F.TheICsacceptaninputvoltage
range of 3V minimum to 30V maximum with little change
in quiescent current (zero switch current). An internal,
low dropout regulator provides a 2.4V supply for most of
the internal circuitry. Supply current increases as switch
current increases at a rate approximately 1/50 of switch
current. This corresponds to a forced Beta of 50 for each
switch. TheICsincorporateundervoltagelockoutbysens-
ing regulator dropout and lockout switching for input
voltages below 2.5V. Hysteresis is not used to maximize
the useful range of input voltage. The typical input voltage
is a 3.3V or 5V logic supply.
BAT (Pin 14): This pin connects to the battery or battery
charger voltage from which the CCFL Royer converter and
LCD contrast converter operate. This voltage is typically
higher than the VIN supply voltage but can be equal or less
than VIN. However, the BAT voltage must be at least 2.1V
greater than the internal 2.4V regulator or 4.5V minimum
up to 30V maximum. This pin provides biasing for the
lamp current programming block, is used with the Royer
pin for floating lamp configurations, and connects to one
input for the open lamp protection circuitry. For floating
lamp configurations, this pin is the noninverting terminal
of a high-side current sense amplifier. The typical quies-
cent current is 50µA into the pin. The BAT and Royer pins
monitor the primary side Royer converter current through
aninternal0.1Ωtopsidecurrentsenseresistor. A0Ato1A
primary side, center tap converter current is translated to
an input signal range of 0mV to 100mV for the current
sense amplifier. This input range translates to a 0µA to
500µAsinkcurrentattheCCFLVC pinthatnullsagainstthe
source current provided by the programmer circuit. The
BAT pin also connects to the top side of an internal clamp
between the BAT and Bulb pins.
LT1182/LT1183
LCD VC (Pin 7): This pin is the output of the LCD contrast
error amplifier and the input of the current comparator for
the LCD contrast regulator. Its uses include frequency
compensation and current limiting. The voltage on the
LCD VC pin determines the current trip level for switch
turnoff. During normal operation, this pin sits at a voltage
between 0.95V (zero switch current) and 2.0V (maximum
switch current). The LCD VC pin has a high impedance
output and permits external voltage clamping to adjust
current limit. A series R/C network to ground provides
stable loop compensation.
LCD PGND (Pin 8): This pin is the emitter of an internal
NPN power switch. LCD contrast switch current flows
through this pin and permits internal, switch-current
sensing. The regulators provide a separate analog ground
and power ground(s) to isolate high current ground paths
from low current signal paths. Linear Technology recom-
mends star-ground layout techniques.
11
LT1182/LT1183/LT1184/LT1184F
U
U
U
PIN FUNCTIONS
LCD VSW (Pin 9): This pin is the collector of the internal
NPN power switch for the LCD contrast regulator. The
power switch provides a minimum of 625mA. Maximum
switch current is a function of duty cycle as internal slope
compensation ensures stability with duty cycles greater
than 50%. Using a driver loop to automatically adapt base
drive current to the minimum required to keep the switch
in a quasi-saturation state yields fast switching times and
high efficiency operation. The ratio of switch current to
driver current is about 50:1.
amplifier and the inverting terminal for the positive-con-
trasterroramplifier.IncomparisontotheLT1182,theFBN
andtheFBPpinstietogetherandcomeoutasonepin.This
scheme permits one polarity of contrast to be regulated.
The proximity of FB to the LCD VSW pin makes it sensitive
to ringing on the switch pin. A small capacitor (0.01µF)
from FB to ground filters switching ripple.
The FB pin requires attention to start-up conditions when
generating negative contrast voltages. The pin has two
stable operating points; regulating to 1.244V for positive
contrast voltages or regulating to –12mV for negative
contrast voltages. Under start-up conditions, the FB pin
heads to a positive voltage. If negative contrast voltages
are generated, tie a diode from the FB pin to ground. This
ensures that the FB pin will clamp before reaching the
positive reference voltage. Switchingaction then pullsthe
FB pin back to its normal servo voltage.
LT1182
FBN (Pin 10): This pin is the noninverting terminal for the
negative contrast control error amplifier. The inverting
terminal is offset from ground by –12mV and defines the
error amplifier output state under start-up conditions. The
FBN pin acts as a summing junction for a resistor divider
network. Input bias current for this pin is typically 1µA
flowing out of the pin. If this pin is not used, force FBN to
greater than 0.5V to deactivate the negative contrast
control input stage. The proximity of FBN to the LCD VSW
pin makes it sensitive to ringing on the switch pin. A small
capacitor (0.01µF) from FBN to ground filters switching
ripple.
LT1183/LT1184/LT1184F
REF(Pin11): Thispinbringsoutthe1.244Vreference. Its
functions include the programming of negative contrast
voltageswithanexternalresistordividernetwork (LT1183
only) and the programming of lamp current for the ICCFL
pin. LTC does not recommend using the REF pin for both
functions at once. The REF pin has a typical output
impedance of 45Ω on the LT1183 and a typical output
impedance of 15Ω on the LT1184/LT1184F. Reference
load current should be limited to a few hundred microam-
peres, otherwise reference regulation will be degraded.
REF is used to generate the maximum programming
current for the ICCFL pin by placing a resistor between the
pins. PWM or DAC control subtracts from the maximum
programmingcurrent. Asmalldecouplingcapacitor(0.1uF)
is recommended to filter switching transients.
FBP (Pin 11): This pin is the inverting terminal for the
positive contrast control error amplifier. The noninverting
terminal is tied to an internal 1.244V reference. Input bias
current for this pin is typically 0.5µA flowing into the pin.
Ifthispinisnotused,groundFBPtodeactivatethepositive
contrast control input stage. The proximity of FBP to the
LCD VSW pin makes it sensitive to ringing on the switch
pin. A small capacitor (0.01µF) from FBP to ground filters
switching ripple.
LT1183
FB (Pin 10): This pin is the common connection between
the noninverting terminal for the negative contrast error
12
LT1182/LT1183/LT1184/LT1184F
W
BLOCK DIAGRAM
LT1182/LT1183 CCFL/LCD Contrast Regulator Top Level Block Diagram
V
BAT
14
ROYER
13
IN
12
UNDER-
VOLTAGE
LOCKOUT
THERMAL
SHUTDOWN
2.4V
REGULATOR
SHUTDOWN
6
SHUTDOWN
LCD
SW
CCFL
SW
V
V
9
16
200kHz
OSC
Q1
Q2
DRIVE 2
DRIVE 1
LOGIC 2
COMP2
LOGIC 1
COMP1
R4
0.1Ω
ANTI-
SAT2
ANTI-
SAT1
+
–
g
m
D2
6V
+
R3
1k
+
I
R2
0.25Ω
LIM
AMP2
I
R1
0.125Ω
LIM
AMP1
Q5
1 ×
–
Q6
2 ×
Q11
–
GAIN = 4.4
0µA TO
GAIN = 4.4
100µA
Q3
2 ×
+
CCFL
Q4
5 ×
Q8
Q7
9 ×
LCD
1 ×
+
+
– –
–
Q10
2 ×
Q9
3 ×
+
V2
1.24V
V1
0.45V
D1
–12mV
–
11
FBP FBN
3
15
BULB
4
8
2
5
7
10
1
LCD LCD
PGND
AGND
DIO
CCFL
CCFL
PGND
I
CCFL
V
V
C
C
LT1183: FBP AND FBN ARE TIED TOGETHER TO CREATE FB
AT PIN 10. THE REFERENCE IS BROUGHT OUT TO PIN 11.
1182 BD01
13
LT1182/LT1183/LT1184/LT1184F
W
BLOCK DIAGRAM
LT1184/LT1184F CCFL Regulator Top Level Block Diagram
V
BAT
14
ROYER
13
IN
12
LT1184: HIGH-SIDE SENSE RESISTOR
R4 AND GM AMPLIFIER ARE REMOVED.
PIN 13 IS NO CONNECT.
UNDER-
VOLTAGE
LOCKOUT
THERMAL
SHUTDOWN
2.4V
REGULATOR
SHUTDOWN
6
SHUTDOWN
CCFL
V
SW
16
200kHz
OSC
Q1
DRIVE 1
LOGIC 1
COMP1
R4
0.1Ω
ANTI-
SAT1
+
–
g
m
D2
6V
+
R3
1k
I
R1
0.125Ω
LIM
AMP1
Q5
1 ×
Q6
2 ×
Q11
–
GAIN = 4.4
Q3
2 ×
+
Q4
5 ×
Q8
1 ×
Q7
9 ×
0µA TO
100µA
CCFL
–
Q10
2 ×
Q9
3 ×
V
REF
V1
0.465V
1.24V
D1
11
3
15
BULB
4
2
5
1
REF
I
AGND
DIO
CCFL
CCFL
PGND
CCFL
V
C
LT1184/LT1184F: REFERENCE IS BROUGHT OUT TO PIN 1.
PINS 7, 8, 9, 10 ARE NO CONNECT.
1184 BD02
U
W U U
APPLICATIONS INFORMATION
Introduction
converter. The lamps operate from DC, but migration
effects damage the lamp and shorten its lifetime. Lamp
drive should contain zero DC component. In addition to
good efficiency, the converter should deliver the lamp
drive in the form of a sine wave. This minimizes EMI and
RF emissions. Such emissions can interfere with other
devices and can also degrade overall operating efficiency.
Sinusoidal CCFL drive maximizes current-to-light conver-
sion in the lamp. The circuit should also permit lamp
intensity control from zero to full brightness with no
hysteresis or “pop-on”.
Current generation portable computers and instruments
use backlit Liquid Crystal Displays (LCDs). These displays
also appear in applications extending to medical equip-
ment, automobiles, gas pumps, and retail terminals. Cold
Cathode Fluorescent Lamps (CCFLs) provide the highest
available efficiency in backlighting the display. Providing
themostlightoutfortheleastamountofinputpoweristhe
mostimportantgoal. TheselampsrequirehighvoltageAC
to operate, mandating an efficient high voltage DC/AC
14
LT1182/LT1183/LT1184/LT1184F
U
W U U
APPLICATIONS INFORMATION
Manufacturers offer a wide array of monochrome and
color displays. LCD display types include passive matrix
and active matrix. These displays differ in operating volt-
age polarity (positive and negative contrast voltage dis-
plays),operatingvoltagerange,contrastadjustrange,and
power consumption. LCD contrast supplies must regu-
late, provide output adjustment over a significant range,
operate over a wide input voltage range, and provide load
currents from milliamps to tens of milliamps.
majority of available displays. Some newer types of dis-
plays require a fairly constant supply voltage and provide
contrastadjustmentthroughadigitalcontrolpin.Aunique,
dual polarity, error amplifier and the selection of a flyback
converter topology allow either positive or negative LCD
contrast voltages to be generated with minor circuit
changes. The difference between the LT1182 and LT1183
is found in the pinout for the inputs of the LCD contrast
error amplifier. The LT1182 brings out the error amplifier
inputs individually for setting up positive and negative
polarity contrast capability. This feature allows an output
connector to determine the choice of contrast operating
polarity by a ground connection. The LT1183 ties the error
amplifier inputs together and brings out an internal refer-
ence. The reference may be used in generating negative
contrast voltages or in programming lamp current.
The small size and battery-powered operation associated
with LCD equipped apparatus dictate low component
count and high efficiency for these circuits. Size con-
straintsplaceseverelimitationsoncircuitarchitectureand
longbatterylifeisapriority. Laptopandhandheldportable
computers offer an excellent example. The CCFL and its
power supply are responsible for almost 50% of the
battery drain. Displays found in newer color machines can
haveacontrastpowersupplybatterydrainashighas20%.
Block Diagram Operation
TheLT1182/LT1183/LT1184/LT1184Farefixedfrequency,
current mode switching regulators. Fixed frequency, cur-
rent mode switchers control switch duty cycle directly by
switch current rather than by output voltage. Referring to
the block diagram for the LT1182/LT1183, the switch for
eachregulatorturnsONatthestartofeachoscillatorcycle.
The switches turn OFF when switch current reaches a
predetermined level. The operation of the CCFL regulator
in the LT1184/LT1184F is identical to that in the LT1182/
LT1183. The control of output lamp current is obtained by
using the output of a unique programming block to set
current trip level. The contrast voltage is controlled by the
output of a dual-input-stage error amplifier, which sets
current trip level. The current mode switching technique
has several advantages. First, it provides excellent rejec-
tion of input voltage variations. Second, it reduces the 90°
phase shift at mid-frequencies in the energy storage
inductor. This simplifies closed-loop frequency compen-
sation under widely varying input voltage or output load
conditions. Finally, it allows simple pulse-by-pulse cur-
rent limiting to provide maximum switch protection under
output overload or short-circuit conditions.
Additionally,allcomponentsincludingPCboardandhard-
ware, usually must fit within the LCD enclosure with a
height restriction of 5mm to 10mm.
The CCFL switching regulator in the LT1182/LT1183/
LT1184/LT1184F typically drives an inductor that acts as
aswitchedmodecurrentsourceforacurrentdrivenRoyer
class converter with efficiencies as high as 90%. The
control loop forces the regulator to pulse-width modulate
the inductor’s average current to maintain constant cur-
rent in the lamp. The constant current’s value, and thus
lamp intensity is programmable. This drive technique
provides a wide range of intensity control. A unique lamp
current programming block permits either grounded-
lamporfloating-lampconfigurations. Grounded-lampcir-
cuits directly control one-half of actual lamp current.
Floating-lamp circuitsdirectly controltheRoyer’sprimary
side converter current. Floating-lamp circuits provide
differentialdrivetothelampandreducethelossfromstray
lamp-to-frame capacitance, extending illumination range.
The LCD contrast switching regulator in the LT1182/
LT1183 is typically configured as a flyback converter and
generates a bias supply for contrast control. Other topol-
ogy choices for generating the bias supply include a boost
converteroraboost/chargepumpconverter. Thesupply’s
variable output permits adjustment of contrast for the
The LT1182/LT1183/LT1184/LT1184F incorporate a low
dropout internal regulator that provides a 2.4V supply for
most of the internal circuitry. This low dropout design
allows input voltage to vary from 3V to 30V with little
15
LT1182/LT1183/LT1184/LT1184F
U
W U U
APPLICATIONS INFORMATION
change in quiescent current. An active low shutdown pin
typically reduces total supply current to 35µA by shutting
off the 2.4V regulator and locking out switching action for
standbyoperation.TheICsincorporateundervoltagelock-
out by sensing regulator dropout and locking out switch-
ing below about 2.5V. The regulators also provide thermal
shutdown protection that locks out switching in the pres-
ence of excessive junction temperatures.
current programming block. This block provides an easy-
to-use interface to program lamp current. The program-
mer circuit also reduces the number of time constants in
the control loop by combining the error signal conversion
scheme and frequency compensation into a single capaci-
tor. The control loop thus exhibits the response of a single
pole system, allows for faster loop transient response and
virtually eliminates overshoot under startup or overload
conditions.
A200kHzoscillatoristhebasicclockforallinternaltiming.
The oscillator turns on an output via its own logic and
driver circuitry. Adaptive anti-sat circuitry detects the
onset of saturation in a power switch and adjusts base
drive current instantaneously to limit switch saturation.
This minimizes driver dissipation and provides rapid turn-
off of the switch. The CCFL power switch is guaranteed to
provide a minimum of 1.25A in the LT1182/LT1183/
LT1184/LT1184FandtheLCDpowerswitchisguaranteed
to provide a minimum of 0.625A in the LT1182/LT1183.
The anti-sat circuitry provides a ratio of switch current to
driver current of about 50:1.
Lamp current is programmed at the input of the program-
mer block, the ICCFL pin. This pin is the input of a shunt
regulator and accepts a DC input current signal of 0µA to
100µA. This input signal is converted to a 0µA to 500uA
sourcecurrentattheCCFLVC pin. Theprogrammercircuit
is simply a current-to-current converter with a gain of five.
ByregulatingtheICCFL pin, theinputprogrammingcurrent
can be set with DAC, PWM or potentiometer control. The
typical input current programming range for 0mA to 6mA
lamp current is 0µA to 50µA.
The ICCFL pin is sensitive to capacitive loading and will
oscillate with capacitance greater than 10pF. For example,
loading the ICCFL pin with a 1× or 10× scope probe causes
oscillation and erratic CCFL regulator operation because
of the probe’s respective input capacitance. A current
meter in series with the ICCFL pin will also produce oscil-
lation due to its shunt capacitance. Use a decoupling
resistorofseveralkilo-ohmsbetweentheICCFL pinandthe
control circuitry if excessive stray capacitance exists. This
is basically free with potentiometer or PWM control as
these control schemes use resistors. A current output
DAC should use an isolating resistor as the DAC can have
significant output capacitance that changes as a function
of input code.
Simplified Lamp Current Programming
A programming block in the LT1182/LT1183/LT1184/
LT1184Fcontrolslampcurrent,permittingeithergrounded-
lamp or floating-lamp configurations. Grounded configu-
rations control lamp current by directly controlling one-
half of actual lamp current and converting it to a feedback
signal to close a control loop. Floating configurations
control lamp current by directly controlling the Royer’s
primary side converter current and generating a feedback
signal to close a control loop.
Previous backlighting solutions have used a traditional
erroramplifierinthecontrollooptoregulatelampcurrent.
ThisapproachconvertedanRMScurrentintoaDCvoltage
for the input of the error amplifier. This approach used
several time constants in order to provide stable loop
frequency compensation. This compensation scheme
meant that the loop had to be fairly slow and that output
overshoot with startup or overload conditions had to be
carefully evaluated in terms of transformer stress and
breakdown voltage requirements.
Grounded-Lamp Configuration
In a grounded-lamp configuration, the low voltage side of
thelampconnectsdirectlytotheLT1182/LT1183/LT1184/
LT1184F DIO pin. This pin is the common connection
between the cathode and anode of two internal diodes. In
previous grounded-lamp solutions, these diodes were
discrete units and are now integrated onto the IC, saving
cost and board space. Bi-directional lamp current flows in
theDIOpinandthus,thediodesconductalternatelyonhalf
The LT1182/LT1183/LT1184/LT1184F eliminate the error
amplifier concept entirely and replace it with a lamp
16
LT1182/LT1183/LT1184/LT1184F
U
W U U
APPLICATIONS INFORMATION
cycles. Lamp current is controlled by monitoring one-half
of the average lamp current. The diode conducting on
negativehalfcycleshasone-tenthofitscurrentdivertedto
theCCFLpinandnullsagainstthesourcecurrentprovided
by the lamp current programmer circuit. The compensa-
tion capacitor on the CCFL VC pin provides stable loop
compensation and an averaging function to the rectified
sinusoidal lamp current. Therefore, input programming
current relates to one-half of average lamp current.
tance include long high voltage lamp leads, reflective
metal foil around the lamp, and displays supplied in metal
enclosures. Losses for a good display are under 5%
whereas losses for a bad display range from 5% to 25%.
Lossy displays are the primary reason to use a floating-
lampconfiguration.Providingsymmetric,differentialdrive
to the lamp reduces the total parasitic loss by one-half.
Maintaining closed-loop control of lamp current in a
floating lamp configuration now necessitates deriving a
feedback signal from the primary side of the Royer trans-
former. Previous solutions have used an external preci-
sion shunt and high side sense amplifier configuration.
This approach has been integrated onto the LT1182/
LT1183/LT1184F for simplicity of design and ease of use.
An internal 0.1W resistor monitors the Royer converter
current and connects between the input terminals of a
high-side sense amplifier. A 0A to 1A Royer primary side,
center tap current is translated to a 0µA to 500uA sink
current at the CCFL VC pin to null against the source
current provided by the lamp current programmer circuit.
The compensation capacitor on the CCFL VC pin provides
stableloopcompensationandanaveragingfunctiontothe
error sink current. Therefore, input programming current
is related to average Royer converter current. Floating-
lamp circuits operate similarly to grounded-lamp circuits,
except for the derivation of the feedback signal.
The transfer function between lamp current and input
programmingcurrentmustbeempiricallydeterminedand
is dependent on the particular lamp/display housing com-
bination used. The lamp and display housing are a distrib-
uted loss structure due to parasitic lamp-to-frame capaci-
tance. This means that the current flowing at the high
voltage side of the lamp is higher than what is flowing at
the DIO pin side of the lamp. The input programming
current is set to control lamp current at the high voltage
side of the lamp, even though the feedback signal is the
lamp current at the bottom of the lamp. This insures that
the lamp is not overdriven which can degrade the lamp’s
operating lifetime.
Floating-Lamp Configuration
In a floating-lamp configuration, the lamp is fully floating
with no galvanic connection to ground. This allows the
transformer to provide symmetric, differential drive to the
lamp. Balanced drive eliminates the field imbalance asso-
ciated with parasitic lamp-to-frame capacitance and re-
duces“thermometering”(unevenlampintensityalongthe
lamp length) at low lamp currents.
The transfer function between primary side converter
current and input programming current must be empiri-
cally determined and is dependent upon a myriad of
factors including lamp characteristics, display construc-
tion, transformer turns ratio, and the tuning of the Royer
oscillator. Once again, lamp current will be slightly higher
at one end of the lamp and input programming current
should be set for this higher level to insure that the lamp
is not overdriven.
Carefully evaluate display designs in relation to the physi-
cal layout of the lamp, it leads and the construction of the
display housing. Parasitic capacitance from any high
voltage point to DC or AC ground creates paths for
unwanted current flow. This parasitic current flow de-
grades electrical efficiency and losses up to 25% have
been observed in practice. As an example, at a Royer
operating frequency of 60kHz, 1pF of stray capacitance
represents an impedance of 2.65MΩ. With an operating
lamp voltage of 400V and an operating lamp current of
6mA, the parasitic current is 150µA. The efficiency loss is
2.5%. Layout techniques that increase parasitic capaci-
The internal 0.1Ω high-side sense resistor on the LT1182/
LT1183/LT1184FisratedforamaximumDCcurrentof1A.
However, this resistor can be damaged by extremely high
surge currents at start-up. The Royer converter typically
usesafewmicrofaradsofbypasscapacitanceatthecenter
tapofthetransformer. Thiscapacitorchargesupwhenthe
system is first powered by the battery pack or an AC wall
adapter.Theamountofcurrentdeliveredatstart-upcanbe
17
LT1182/LT1183/LT1184/LT1184F
U
W U U
APPLICATIONS INFORMATION
very large if the total impedance in this path is small and
the voltage source has high current capability. Linear
Technology recommends the use of an aluminum electro-
lytic for the transformer center tap bypass capacitor with
an ESR greater than or equal to 0.5Ω. This lowers the peak
surge currents to an acceptable level. In general, the wire
and trace inductance in this path also help reduce the di/
dt of the surge current. This issue only exists with floating
lamp circuits as grounded-lamp circuits do not make use
of the high-side sense resistor.
izedcalibratedvoltageandcurrentprobes,widebandRMS
voltmeters, a photometer, and a calorimeter (for the
backlight enthusiast). Linear Technology’s Application
Note 55 and Design Note 101 contain detailed information
regarding equipment needs.
Input Supply Voltage Operating Range
The backlight/LCD contrast control circuits must operate
over a wide range of input supply voltage and provide
excellent line regulation for the lamp current and the
contrast output voltage. This range includes the normal
range of the battery pack itself as well as the AC wall
adapter voltage, which is normally much higher than the
maximum battery voltage. A typical input supply is 7V to
28V; a 4 to 1 supply range.
Optimizing Optical Efficiency vs Electrical Efficiency
Evaluating the performance of an LCD backlight requires
the measurement of both electrical and photometric effi-
ciencies. The best optical efficiency operating point does
not necessarily correspond to the best electrical effi-
ciency. However, these two operating points are generally
close. The desired goal is to maximize the amount of light
out for the least amount of input power. It is possible to
construct backlight circuits that operate with over 90%
electrical efficiency, but produce significantly less light
output than circuits that operate at 80% electrical effi-
ciency.
Operation of the CCFL control circuitry from the AC wall
adapter generates the worst-case stress for the CCFL
transformer. Evaluations of loop compensation for over-
shoot on startup transients and overload conditions are
essential to avoid destructive arcing, overheating, and
transformerfailure.Open-lampconditionsforcetheRoyer
converter to operate open-loop. Component stress is
againworst-casewithmaximuminputvoltageconditions.
The LT1182/LT1183/LT1184/LT1184F open-lamp pro-
tection clamps the maximum transformer secondary volt-
age to safe levels and transfers the regulator loop from
current mode operation into voltage mode operation.
Other fault conditions include board shorts and compo-
nent failures. These fault conditions can increase primary
side currents to very high levels, especially at maximum
input voltage conditions. Solutions to these fault condi-
tions include electrical and thermal fuses in the supply
voltage trace.
The best electrical efficiency typically occur’s just as the
CCFL’s transformer drive waveforms begin to exhibit
artifactsofhigherorderharmonicsreflectedbackfromthe
Royer transformer secondary. Maximizing electrical effi-
ciency equates to smaller values for the Royer primary
side, resonating capacitor and larger values for the Royer
secondary side ballast capacitor. The best optical effi-
ciency occurs with nearly ideal sinusoidal drive to the
lamp. Maximizing optical efficiency equates to larger
valuesfortheRoyerprimarysideresonatingcapacitorand
smallervaluesfortheRoyersecondarysideballastcapaci-
tor. The preferred operating point for the CCFL converter
is somewhere in between the best electrical efficiency and
the best optical efficiency. This operating point maximizes
photometric output per watt of input power.
Improvements in battery technology are increasing bat-
tery lifetimes and decreasing battery voltages required by
the portable systems. However, operation at reduced
battery voltages requires higher, turns-ratio transformers
fortheCCFLtogenerateequivalentoutputdrivecapability.
Thepenaltyincurredwithhighratiotransformersishigher,
circulating currents acting on the same primary side
components. Losstermsincreaseandelectricalefficiency
often decreases.
Making accurate and repeatable measurements of electri-
cal and optical efficiency is difficult under the best circum-
stances. Requirements include high voltage measure-
mentsandequipmentspecifiedforthisoperation, special-
18
LT1182/LT1183/LT1184/LT1184F
U
W U U
APPLICATIONS INFORMATION
Size Constraints
Applications Support
Tighter length, width, and height constraints for CCFL and
LCDcontrastcontrolcircuitryaretheresultofLCDdisplay
enclosure sizes remaining fairly constant while display
screen sizes have increased. Space requirements for
connector hardware include the input power supply and
control signal connector, the lamp connector, and the
contrast output voltage connector.
Linear Technology invests an enormous amount of time,
resources, and technical expertise in understanding, de-
signing and evaluating backlight/LCD contrast solutions
for system designers. The design of an efficient and
compact LCD backlight system is a study of compromise
in a transduced electronic system. Every aspect of the
design is interrelated and any design change requires
complete re-evaluation for all other critical design param-
eters. Linear Technology has engineered one of the most
complete test and evaluation setups for backlight designs
and understands the issues and tradeoffs in achieving a
compact, effficient and economical customer solution.
Linear Technology welcomes the opportunity to discuss,
design, evaluate, andoptimizeanybacklight/LCDcontrast
system with a customer. For further information on back-
light/LCD contrast designs, consult the references listed
below.
Even though size requirements are shrinking, the high
voltage AC required to drive the lamp has not decreased.
In some cases, the use of longer bulbs for color, portable
equipment has increased the high voltage requirement.
Accommodating the high voltage on the circuit board
dictates certain layout spacings and routings, involves
providing creepages and clearances in the transformer
design, and most importantly, involves routing a hole
underneath the CCFL transformer. Routing this hole mini-
mizes high voltage leakage paths and prevents moisture
buildup that can result in destructive arcing. In addition to
high voltage layout techniques, use appropriate layout
techniques for isolating high current paths from low-
current signal paths.
References
1. Williams, Jim. August 1992. Illumination Circuitry for
Liquid Crystal Displays. Linear Technology Corporation,
Application Note 49.
This leaves the remaining space for control circuitry at a
premium. Minimum component count is required and
minimum size for the components used is required. This
squeeze on component size is often in direct conflict with
the goals of maximizing battery life and efficiency. Com-
promise is often the only remaining choice.
2. Williams, Jim. August 1993. Techniques for 92% Effi-
cient LCD Illumination. Linear Technology Corporation,
Application Note 55.
3. Bonte, Anthony. March 1995. LT1182 Floating CCFL
with Dual Polarity Contrast. Linear Technology Corpora-
tion, Design Note 99.
LCD Contrast Circuits
4. Williams, Jim. April 1995. A Precision Wideband Cur-
rent Probe for LCD Backlight Meaasurement. Linear Tech-
nology Corporation, Design Note 101.
The LCD contrast switching regulator on the LT1182/
LT1183 operates in many standard switching configura-
tions and is used as a classic DC/DC converter. The dual-
input-stage error amplifier easily regulates either positive
or negative contrast voltages. Topology choices for the
converter include single inductor and transformer-based
solutions. The switching regulator operates equally well
either in continuous mode or discontinuous mode. Effi-
ciencies for LCD contrast circuits range from 75% to 85%
and depend on the total power drain of the particular
display. Adjustment control of the LCD contrast voltage is
provided by either potentiometer, PWM, or DAC control.
19
LT1182/LT1183/LT1184/LT1184F
U
TYPICAL APPLICATIONS N
90% Efficient Grounded CCFL Configuration with Negative Polarity LCD Contrast
UP TO 6mA
LAMP
C1 MUST BE A LOW LOSS CAPACITOR,
C1 = WIMA MKP-20
C2
27pF
3kV
Q1, Q2 = ZETEX ZTX849 OR ROHM 2SC5001
L1 = COILTRONICS CTX210605
10
6
L1
L2 = COILTRONICS CTX100-4
3
2
1
4
5
BAT
L3 = COILTRONICS CTX02-12403
*DO NOT SUBSTITUTE COMPONENTS
COILTRONICS (407) 241-7876
8V TO 28V
+
C3B
+
+
C3A
2.2µF
35V
2.2µF
35V
C5
R2
220k
1000pF
VARYING THE V(CONTRAST)
R1
750Ω
THE I
CURRENT REQUIRED FOR AN
CCFL
VOLTAGE FROM 0V TO 5V GIVES
VARIABLE NEGATIVE CONTRAST
FROM –10V TO –30V
C1*
RMS BULB CURRENT IS:
–3
0.068µF
I
(9 × 10 ) (I
).
CCFL
BULB
C12
2.2µF
35V
0% TO 90% DUTY CYCLE FOR THE PWM
SIGNAL CORRESPONDS TO 0 TO 6mA.
R3
100k
Q2*
Q1*
D5
BAT85
L3
D3
1N5934A
24V
4
2
6
L2
+
D1
1N5818
C11
100µH
22µF
R4
1
2
3
4
5
6
7
8
16
D2
1N914
CCFL
35V
CCFL V
9
SW
38.3k
1%
PGND
R5,38.3k, 1%
V (PWM)
0V TO 5V
1kHz PWM
15
14
13
12
11
10
9
NEGCON
I
BULB
CCFL
N = 1:2
D4
1N914
+
DIO
BAT
C6
2.2µF
C7, 1µF
LT1183
C
V
≥ 3V
IN
CCFL V
AGND
SHDN
ROYER
+
C4
2.2µF
V
IN
REF
FB
SHUTDOWN
C8,0.68µF
C10
0.1µF
R9, 4.99k, 1%
LCD V
LCD
PGND
C
R7, 10k
R11
40.2k
1%
LCD V
SW
R10, 10k, 1%
V (CONTRAST)
0V TO 5V
D5
1N4148
C9
0.01µF
1182 TA02
20
LT1182/LT1183/LT1184/LT1184F
U
TYPICAL APPLICATIONS N
LT1184F Floating CCFL with Potentiometer Control of Lamp Current
UP TO 6mA
LAMP
ALUMINUM ELECTROLYTIC IS RECOMMENDED FOR C3B WITH AN
ESR ≥ 0.5Ω TO PREVENT DAMAGE TO THE LT1184F HIGH-SIDE
SENSE RESISTOR DUE TO SURGE CURRENTS AT TURN-ON.
C2
27pF
3kV
10
6
C1 MUST BE A LOW LOSS CAPACITOR, C1 = WIMA MKP-20
Q1, Q2 = ZETEX ZTX849 OR ROHM 2SC5001
L1 = COILTRONICS CTX210605
L1
3
2
1
5
4
BAT
8V TO 28V
L2 = COILTRONICS CTX100-4
+
C3B
+
C3A
2.2µF
35V
2.2µF
*DO NOT SUBSTITUTE COMPONENTS
C5
1000pF
R2
220k
35V
COILTRONICS (407) 241-7876
R1
750Ω
C1*
0.068µF
0µA TO 45µA I
0mA TO 6mA LAMP CURRENT FOR A
TYPICAL DISPLAY.
CURRENT GIVES
CCFL
R3
100k
Q2*
Q1*
D5
BAT85
L2
100µH
D1
1N5818
1
2
3
4
5
6
7
8
16
CCFL
PGND
CCFL V
SW
15
14
13
12
11
10
9
I
BULB
CCFL
DIO
BAT
C7, 1µF
LT1184F
C
CCFL V
AGND
SHDN
NC
ROYER
V
IN
V
IN
≥ 3V
+
C4
2.2µF
SHUTDOWN
REF
NC
R4
15.4k
1%
R5
50k
10 TURN
NC
NC
1182 TA03
21
LT1182/LT1183/LT1184/LT1184F
U
TYPICAL APPLICATIONS N
LT1182/LT1183 I
PWM Programming
LT1183 I
PWM Programming with V
CCFL REF
CCFL
V (PWM)
0V TO 5V
1kHz PWM
R1
40.5k
R2
FROM V
REF
40.5k
V (PWM)
0V TO 5V
R1
330Ω
TO I
PIN
CCFL
0% to 90% DC =
0µA to 50µA
Q1
VN2222L
+
1kHz PWM
C1
R1 AND R2 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
0% to 90% DC =
2.2µF
0µA to 50µA
R2
7.15k
R3
1182 TA04
7.15k
TO I
PIN
CCFL
+
C1
22µF
R1 PREVENTS OSCILLATION.
R2 AND R3 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
LT1184/LT1184F I
PWM Programming
CCFL
R1
40.35k
R2
40.35k
V (PWM)
0V TO 5V
1kHz PWM
1182 TA08
TO I
PIN
CCFL
0% to 90% DC =
0µA to 50µA
+
C1
2.2µF
R1 AND R2 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
LT1184/LT1184F I
PWM Programming with V
REF
CCFL
1182 TA05
FROM V
REF
V (PWM)
0V TO 5V
R1
330Ω
Q1
1kHz PWM
LT1183 I
CCFL
Programming
with Potentiometer Control
VN2222L
0% to 90% DC =
0µA to 50µA
R2
6.98k
R3
R2
R1
6.98k
50k
15.9k
TO I
PIN
CCFL
+
V
REF
TO I
PIN
CCFL
C1
22µF
R1 PREVENTS OSCILLATION.
R2 AND R3 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
R1 AND R2 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
1182 TA06
I
= 12µA TO 50µA.
CCFL
1182 TA09
LT1184/LT1184F I
Programming
CCFL
with Potentiometer Control
LT1183 I
PWM Programming with V
REF
CCFL
R2
50k
R1
15.5k
FROM V
REF
V
TO I
PIN
REF
CCFL
R1
R1 AND R2 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
CCFL
R2
3.57k
R3
7.15k
3.57k
1182 TA07
I
= 12µA TO 50µA.
TO I
PIN
CCFL
V (PWM)
0V TO 5V
+
Q1
VN2222L
C1
22µF
1kHz PWM
10 to 100% DC =
50µA TO 0µA
LT1182/LT1183/LT1184/LT1184F
R1, R2 AND R3 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
I
Programming with DAC Control
CCFL
1182 TA10
R1
5k
DAC
TO I
PIN
CCFL
STRAY OUTPUT
CAPACITANCE
LT1184/LT1184F I
PWM Programming with V
REF
CCFL
FROM V
REF
CURRENT SOURCE
DAC
R1
R2
3.48k
R3
3.48k
R1 DECOUPLES THE DAC OUTPUT CAPACITANCE
FROM THE I PIN.
6.98k
1182 TA12
CCFL
TO I
PIN
CCFL
V (PWM)
0V TO 5V
+
Q1
VN2222L
C1
22µF
1kHz PWM
10 to 100% DC =
50µA TO 0µA
R1, R2 AND R3 ARE IDEAL VALUES.
USE NEAREST 1% VALUE.
1182 TA11
22
LT1182/LT1183/LT1184/LT1184F
U
TYPICAL APPLICATIONS N
LT1182 LCD Contrast Positive Boost Converter
BAT
8V TO 28V
+
C13
2.2µF
35V
L3
50µH
COILTRONICS CTX50-4
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CCFL
POSCON
OUT
CCFL V
SW
PGND
V
≥ V
IN
+
C11
D5
1N914
I
BULB
BAT
22µF
CCFL
35V
DIO
R12
20k
LT1182
C
V
IN
CCFL V
AGND
SHDN
ROYER
≥ 3V
+
C4
2.2µF
R13
8.45k
1%
V
IN
C8
0.068µF
FBP
FBN
R7
33K
R14
1.21k
1%
C10
0.01µF
LCD V
LCD
PGND
C
LCD V
SW
1182 TA12
LT1182 LCD Contrast Positive Boost/Charge Pump Converter
BAT
8V TO 28V
+
C13
L3
2.2µF
50µH
35V
COILTRONICS CTX50-4
C11
22µF
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
D5
CCFL
CCFL V
35V
SW
PGND
1N914
POSCON
+
I
BULB
BAT
CCFL
V
≥ V
OUT
IN
+
C11
D4
22µF
1N914
DIO
35V
LT1182
C
R12
20k
V
IN
CCFL V
AGND
SHDN
ROYER
≥ 3V
+
C4
2.2µF
R13
V
IN
8.45k
1%
C8
0.068µF
FBP
FBN
R7
33K
C10
0.01µF
R14
1.21k
1%
LCD V
LCD
PGND
C
LCD V
SW
1182 TA13
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
23
LT1182/LT1183/LT1184/LT1184F
U
TYPICAL APPLICATIONS N
LT1182 LCD Contrast Positive to Negative/Charge Pump Converter
1
2
3
4
5
6
7
8
16
CCFL
BAT
CCFL V
SW
PGND
8V TO 28V
+
C13
2.2µF
35V
15
14
13
12
11
10
9
L3
I
BULB
BAT
CCFL
CTX50-4
COILTRONICS CTX50-4
DIO
C11
LT1182
C
V
22µF
IN
≥ 3V
D5
CCFL V
AGND
SHDN
ROYER
35V
+
1N914
C4
2.2µF
NEGCON
V
IN
|V | ≥ V
OUT
IN
C11
C9
0.01µF
D4
C8
0.068µF
22µF
FBP
FBN
R7
33K
+
1N914
35V
LCD V
C
LCD
PGND
LCD V
SW
R11
20k
1%
R9
4.99k
1%
R10
10k
1%
1182 TA14
5V
RELATED PARTS
PART NUMBER
FREQUENCY
SWITCH CURRENT
DESCRIPTION
LT1107
63kHz
Hysteretic
1A
Micropower DC/DC Converter for LCD Contrast Control
LT1172
LT1173
LT1186
LT1372
100kHz
1.25A
1A
Current Mode Switching Regulator for CCFL or LCD
Contrast Control
24kHZ
Hysteretic
Micropower DC/DC Converter for LCD Contrast Control
200kHz
1.25A
1.5A
CCFL Switching Regulator with DAC for “Bits to
Brightness Control”
500kHz
Current Mode Switching Regulator for CCFL or LCD
Contrast Control
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
S Package
16-Lead Plastic SOIC
0.386 – 0.394*
(9.804 – 10.008)
0.010 – 0.020
(0.254 – 0.508)
16
15
14
13
12
11
10
9
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0° – 8° TYP
0.150 – 0.157*
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
0.016 – 0.050
0.406 – 1.270
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
1
2
3
4
5
6
7
8
LT/GP 0495 10K • PRINTED IN USA
24 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LINEAR TECHNOLOGY CORPORATION 1995
相关型号：
SI9130DB
5- and 3.3-V Step-Down Synchronous ConvertersWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9135LG-T1
SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9135LG-T1-E3
SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9135_11
SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9136_11
Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9130CG-T1-E3
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9130LG-T1-E3
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9130_11
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9137
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9137DB
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9137LG
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
SI9122E
500-kHz Half-Bridge DC/DC Controller with Integrated Secondary Synchronous Rectification DriversWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
-
VISHAY
©2020 ICPDF网 联系我们和版权申明