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
● 0.725 0.795 0.865 V
V
REF
– I
CCFL
Summing Voltage Measured on LT1184/LT1184F 0.740 0.775 0.810 V
● 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 ● 1.214 1.244 1.274 V
REF1 Voltage Line Regulation 3V ≤ V
IN
≤ 30V, LCD V
C
= 0.8V ● 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 ● 0.35 1.0 µA
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 ● –27 –12 –1 mV
Offset Voltage Line Regulation 3V ≤ V
IN
≤ 30V, LCD V
C
= 0.8V ● 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 ● –3.0 – 1.0 µA
g
m
FBP/FB to LCD V
C
Transconductance LT1182: ∆I
VC
= ±25µA, FBN = 1V 650 900 1150 µmhos
LT1183: ∆I
VC
= ±25µA ● 500 900 1300 µmhos
FBN/FB to LCD V
C
Transconductance LT1182: ∆I
VC
= ±25µA, FBP = GND 550 800 1050 µmhos
LT1183: ∆I
VC
= ±25µA ● 400 800 1200 µmhos
LCD Error Amplifier Source Current LT1182: FBP = FBN = 1V or 0.25V, ● 50 100 175 µA
LT1183: FB = 1V or 0.25V
LCD Error Amplifier Sink Current LT1182: FBP = FBN = 1.5V or –0.25V, ● 35 100 175 µA
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% ● 0.625 1.00 1.5 A
Duty Cycle = 75% (Note 3)
● 0.400 0.85 1.3 A
V
SAT2
LCD Switch On-Resistance LCD I
SW
= 0.5A ● 1.0 1.65 Ω
∆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 µs
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 ● 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.
