LT1940 Ver la hoja de datos (PDF) - Linear Technology
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LT1940 Datasheet PDF : 20 Pages
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LT1940/LT1940L
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 5V, VBOOST = 8V unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Foldback Frequency
Switch Current Limit
VFB = 0V
Note 3
150
kHz
1.8
2.4
3.2
A
Switch VCESAT
Switch Leakage Current
ISW = 1A
210 320
mV
10
µA
Minimum Boost Voltage Above Switch (Note 4)
BOOST Pin Current
RUN/SS Current
ISW = 1A
ISW = 1A
1.8
2.5
V
20
30
mA
2.3
µA
RUN/SS Threshold
0.3
0.6
V
PG Threshold Offset
PG Voltage Output Low
PG Pin Leakage
VFB Rising
VFB = 1V, IPG = 250µA
VPG = 2V
90
125 160
mV
0.22
0.4
V
0.1
1
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1940E is 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.
Note 3: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at high duty cycle.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency, VOUT = 1.8V
90
VOUT = 1.8V
L = 2.2µH (SUMIDA CR43-2R2)
TA = 25°C
80
VIN = 5V
70
60
Efficiency, VOUT = 3.3V
100
VOUT = 3.3V
L = 3.3µH (SUMIDA CR43-3R3)
90 TA = 25°C
VIN = 5V
80
VIN = 12V
70
VIN = 18V
60
50
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G01
50
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G02
Efficiency, VOUT = 5V
100
VOUT = 5V
L = 4.7µH (SUMIDA CR43-4R7)
TA = 25°C
90
VIN = 8V
80
VIN = 12V
VIN = 18V
70
60
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G03
1940fa
3
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