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
3.4
MAX
3.7
3.0
5.2
500
2
UNITS
V
l
l
Minimum Operating Voltage, V
Minimum Operating Voltage, V
IN1
V
= 12V
2.5
V
IN2
IN1
V
IN1
V
IN2
Quiescent Current
Quiescent Current
Not Switching
Not Switching
4.3
mA
ꢀA
320
0.1
Shutdown Current (V + V
)
IN2
V
= 0.3V
SHDN
ꢀA
IN1
FB Voltage
0.790
0.784
0.800
0.814
0.816
V
V
l
l
FB Pin Bias Current (Note 3)
FB Voltage Line Regulation
Error Amp Transconductance
Error Amp Voltage Gain
V
= 0.800V, V = 0.4V
50
0.01
300
600
2.5
1
300
nA
%/V
ꢀS
FB
C
5V < V < 40V
IN
V/V
A/V
MHz
Deg
V to Switch Current Gain
C
l
l
Switching Frequency
Switching Phase
R = 33.2k
0.92
150
84
1.06
210
T
R = 33.2k
180
T
Maximum Duty Cycle (Note 4)
R = 33.2k
90
80
98
%
%
%
T
T
T
R = 7.50k
R = 169k
Foldback Frequency
R = 33.2k, V = 0V
120
2.6
kHz
A
T
FB
l
Switch Current Limit (Note 5)
Duty Cycle = 15%
2.0
3.2
Switch V
I
= 1.5A
300
0.01
1.7
mV
ꢀA
V
CESAT
SW
Switch Leakage Current
Minimum Boost Voltage
Boost Pin Current
1
2.5
50
I
= 1.5A
35
mA
ꢀA
mV
V
SW
TRACK/SS Pin Current
PG Threshold Offset
V
= 0V
0.8
56
1.2
2.2
110
0.4
1
TRACK/SS
V
V
V
Rising
75
FB
FB
PG
PG Voltage Output Low
PG Pin Leakage
= 0.6V, I = 250ꢀA
0.13
0.01
2.63
8
PG
= 2V
ꢀA
V
SHDN Threshold Voltage
SHDN Input Current (Note 6)
2.53
6
2.73
10
V
= 60mV Above Threshold Voltage
ꢀA
ꢀA
V
SHDN
SHDN Threshold Current Hysteresis
SYNC Threshold Voltage
5.5
1
7.5
9.5
1.5
2.5
1.25
SYNC Input Frequency
0.25
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 3: Current flows out of pin.
Note 4: V =12V. Circuitry increases the maximum duty cycle of the
BOOST
LT3508 when V
> V + 2.5V. See “Minimum Operating Voltage” in
BOOST
IN
the Applications Information section for details.
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 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
Linear [ Linear ]
