LT3508 Просмотр технического описания (PDF) - Linear Technology
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LT3508 Datasheet PDF : 24 Pages
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LT3508
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 = 17V unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Minimum Operating Voltage, VIN1
Minimum Operating Voltage, VIN2
VIN1 Quiescent Current
VIN2 Quiescent Current
Shutdown Current (VIN1 + VIN2)
FB Voltage
VIN1 = 12V
Not Switching
Not Switching
VSHDN = 0.3V
l
3.4
3.7
V
l
2.5
3.0
V
4.3
5.2
mA
320
500
μA
0.1
2
μA
0.790 0.800 0.814
V
l 0.784
0.816
V
FB Pin Bias Current (Note 3)
VFB = 0.800V, VC = 0.4V
l
50
300
nA
FB Voltage Line Regulation
Error Amp Transconductance
5V < VIN < 40V
0.01
%/V
300
μS
Error Amp Voltage Gain
600
V/V
VC to Switch Current Gain
Switching Frequency
Switching Phase
Maximum Duty Cycle (Note 4)
Foldback Frequency
Switch Current Limit (Note 5)
RT = 33.2k
RT = 33.2k
RT = 33.2k
RT = 7.50k
RT = 169k
RT = 33.2k, VFB = 0V
Duty Cycle = 15%
2.5
A/V
l 0.92
1
1.06
MHz
150
180
210
Deg
l 84
90
%
80
%
98
%
120
kHz
l 2.0
2.6
3.2
A
Switch VCESAT
Switch Leakage Current
ISW = 1.5A
300
mV
0.01
1
μA
Minimum Boost Voltage
1.7
2.5
V
Boost Pin Current
TRACK/SS Pin Current
PG Threshold Offset
ISW = 1.5A
VTRACK/SS = 0V
VFB Rising
35
50
mA
0.8
1.2
2.2
μA
56
75
110
mV
PG Voltage Output Low
PG Pin Leakage
SHDN Threshold Voltage
SHDN Input Current (Note 6)
SHDN Threshold Current Hysteresis
VFB = 0.6V, IPG = 250μA
VPG = 2V
VSHDN = 60mV Above Threshold Voltage
0.13
0.4
V
0.01
1
μA
2.53 2.63 2.73
V
6
8
10
μA
5.5
7.5
9.5
μA
SYNC Threshold Voltage
1
1.25
1.5
V
SYNC Input Frequency
0.25
2.5
MHz
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: The LT3508E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3508I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3508H is guaranteed over the full –40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetimes. Operating lifetime is derated at junction
temperatures greater than 125°C.
Note 3: Current flows out of pin.
Note 4: VBOOST =12V. Circuitry increases the maximum duty cycle of the
LT3508 when VBOOST > VIN + 2.5V. See “Minimum Operating Voltage” in
the Applications Information section for details.
Note 5: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at higher duty cycles.
Note 6: Current flows into pin.
Note 7: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
range when overtemperature protection is active. Continuous operation
above the specified maximum operating junction temperature may impair
device reliability.
3508fb
3
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