LT3474 Просмотр технического описания (PDF) - Linear Technology
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LT3474 Datasheet PDF : 20 Pages
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LT3474/LT3474-1
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, VBOOST = 16V, VOUT = 4V unless otherwise noted (Note 3).
PARAMETER
CONDITIONS
MIN
TYP MAX UNITS
Reference Voltage Line Regulation
Reference Voltage Load Regulation
VADJ Pin Bias Current (Note 4)
5V < VIN < 36V
0 < IREF < 250μA
0.01
%/V
0.0002
%/μA
l
20
400
nA
Switching Frequency
RT = 80.6k
470
500
530
kHz
l 450
540
kHz
Maximum Duty Cycle
Foldback Frequency
RT = 80.6k
RT = 10k
RT = 232k
RT = 80.6k, VOUT = 0V
l 90
95
%
76
%
98
%
70
kHz
SHDN Threshold (to Switch)
2.6
2.65
2.7
V
SHDN Pin Current (Note 5)
PWM Threshold
VSHDN = SHDN Threshold
8.3
10.3
12.3
μA
0.4
0.9
1.2
V
VC Switching Threshold
VC Source Current
VC = 1V
0.8
V
100
μA
VC Sink Current
LED to VC Current Gain
LED to VC Transresistance
VC to Switch Current Gain
VC = 1V
100
μA
1.5
μA/mA
1
V/mA
2
A/V
VC Clamp Voltage
VC Pin Current in PWM Mode
OUT Pin Clamp Voltage (LT3474)
VC = 1V, VPWM = 0.3V
1.9
V
l
0.01
1
μA
13.2
13.8
14.5
V
OUT Pin Current in PWM Mode
Switch Current Limit (Note 6)
VOUT = 4V, VPWM = 0.3V
–40°C to 85°C
LT3474I, LT3474I-1 at 125°C
l
0.1
10
μA
l 1.6
2.1
3.2
A
1.5
3.2
A
Switch VCESAT
ISW = 1A
380
500
mV
Boost Pin Current
Switch Leakage Current
ISW = 1A
30
50
mA
0.01
1
μA
Minimum Boost Voltage (Note 7)
1.9
2.5
V
Boost Diode Forward Voltage
IDIO = 100mA
600
mV
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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