LT1184F_15 Datasheet, PDF (4/24 Pages) Linear Technology – CCFL/LCD Contrast Switching Regulators

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
CONDITIONS
Measured on LT1183
V_REF – I_CCFL Summing Voltage
Measured on LT1184/LT1184F
REF1
g_m
I_LIM2
V_SAT2
∆I_Q
∆I_SW2
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
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
LCD Switch Current Limit
LCD Switch On-Resistance
Supply Current Increase During
LCD Switch On-Time
Switch Minimum On-Time
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
MIN
0.760
q 0.725
0.740
q 0.705
1.224
q 1.214
q
TYP
0.795
0.795
0.775
0.775
1.244
1.244
0.01
MAX
0.830
0.865
0.810
0.845
1.264
1.274
0.03
UNITS
V
V
V
V
V
V
%/V
q
0.35 1.0
µA
– 20 – 12 – 4
mV
q – 27 – 12 – 1
mV
q
0.01 0.2
%/V
q – 3.0
650
q 500
550
q 400
q 50
– 1.0
µA
900 1150 µmhos
900 1300 µmhos
800 1050 µmhos
800 1200 µmhos
100 175
µA
q 35 100 175
µA
0.01 0.3
1.7 2.0 2.4
0.6 0.95 1.3
q 0.625 1.00 1.5
q 0.400 0.85 1.3
q
1.0 1.65
20 30
V
V
V
A
A
Ω
mA/A
0.45
µs
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