LT3475_15 Datasheet, PDF (3/20 Pages) Linear Technology – Dual Step-Down 1.5A LED Driver

LT3475/LT3475-1
ELECTRICAL CHARACTERISTICS _{The ● denotes the specifications which apply over the full operating}
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 12V, V_BOOST = 16V, V_OUT = 4V unless otherwise noted (Note 3)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
LED Pin Current
REF Voltage
V_ADJ Tied to V_REF • 2/3
V_ADJ Tied to V_REF • 7/30
LT3475E/LT3475E-1 0°C to 85°C
0.97 1.00 1.03
A
● 0.94
1.04
A
0.336 0.350 0.364
A
0.325
0.375
A
● 0.31
0.385
A
● 1.22 1.25 1.27
V
Reference Voltage Line Regulation
Reference Voltage Load Regulation
V_ADJ Pin Bias Current (Note 4)
Switching Frequency
Maximum Duty Cycle
Switching Phase
Foldback Frequency
SHDN Threshold (to Switch)
4V < V_IN < 40V
0 < I_REF < 500μA
R_T = 24.3k
R_T = 24.3k
R_T = 4.32k
R_T = 100k
R_T = 24.3k
R_T = 24.3k, V_OUT = 0V
0.05
0.0002
●
40
400
● 530
600
640
● 90
95
80
98
150
180
210
80
2.5
2.6 2.74
%/V
%/μA
nA
kHz
%
%
%
Deg
kHz
V
SHDN Pin Current (Note 5)
PWM Threshold
V_SHDN = 2.6V
7
9
11
μA
0.3
0.8
1.2
V
V_C Switching Threshold
V_C Source Current
V_C Sink Current
LED to V_C Transresistance
LED to V_C Current Gain
V_C to Switch Current Gain
V_C Clamp Voltage
V_C Pin Current in PWM Mode
OUT Pin Clamp Voltage (LT3475)
OUT Pin Current in PWM Mode
Switch Current Limit (Note 6)
V_C = 1V
V_C = 1V
V_C = 1V, V_PWM = 0.3V
V_OUT = 4V, V_PWM = 0.3V
0.8
V
50
μA
50
μA
500
V/A
1
mA/μA
2.6
A/V
1.8
V
●
10
400
nA
13.5
14
14.5
V
●
25
50
μA
2.3
2.7
3.2
A
Switch V_CESAT
BOOST Pin Current
Switch Leakage Current
Minimum Boost Voltage Above SW
I_SW =1.5A
I_SW =1.5A
350
500
mV
25
40
mA
0.1
10
μA
1.8
2.5
V
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 3: The LT3475E and LT3475E-1 are guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LT3475I and LT3475I-1
are guaranteed to meet performance specifications over the –40°C to
125°C operating temperature range.
Note 4: Current flows out of pin.
Note 5: Current flows into pin.
Note 6: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at higher duty cycles.
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