LT3474/LT3474-1
ELECTRICAL CHARACTERISTICS
PARAMETER
Reference Voltage Line Regulation
Reference Voltage Load Regulation
V
ADJ
Pin Bias Current (Note 4)
Switching Frequency
Maximum Duty Cycle
R
T
= 80.6k
R
T
= 80.6k
R
T
= 10k
R
T
= 232k
R
T
= 80.6k, V
OUT
= 0V
2.6
V
SHDN
= SHDN Threshold
8.3
0.4
V
C
= 1V
V
C
= 1V
The
l
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).
CONDITIONS
5V < V
IN
< 36V
0 < I
REF
< 250μA
l
l
l
MIN
TYP
0.01
0.0002
20
MAX
UNITS
%/V
%/μA
400
530
540
nA
kHz
kHz
%
%
%
kHz
470
450
90
500
95
76
98
70
2.65
10.3
0.9
0.8
100
100
1.5
1
2
1.9
Foldback Frequency
SHDN Threshold (to Switch)
SHDN Pin Current (Note 5)
PWM Threshold
V
C
Switching Threshold
V
C
Source Current
V
C
Sink Current
LED to V
C
Current Gain
LED to V
C
Transresistance
V
C
to Switch Current Gain
V
C
Clamp Voltage
V
C
Pin Current in PWM Mode
OUT Pin Clamp Voltage (LT3474)
OUT Pin Current in PWM Mode
Switch Current Limit (Note 6)
Switch V
CESAT
Boost Pin Current
Switch Leakage Current
Minimum Boost Voltage (Note 7)
Boost Diode Forward Voltage
2.7
12.3
1.2
V
μA
V
V
μA
μA
μA/mA
V/mA
A/V
V
V
C
= 1V, V
PWM
= 0.3V
V
OUT
= 4V, V
PWM
= 0.3V
–40°C to 85°C
LT3474I, LT3474I-1 at 125°C
I
SW
= 1A
I
SW
= 1A
l
0.01
13.2
13.8
0.1
1.6
1.5
2.1
380
30
0.01
1.9
1
14.5
10
3.2
3.2
500
50
1
2.5
μA
V
μA
A
A
mV
mA
μA
V
mV
l
l
I
DIO
= 100mA
600
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 LT3474E and LT3474E-1 are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LT3474I and LT3474I-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.
Note 7:
This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
3474fd
3
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