LT3975
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
PARAMETER
Switch Current Limit
Foldback Switch Current Limit
CONDITIONS
MIN
4
TYP
5.4
3.3
MAX
6.8
UNITS
A
V
V
= 1V
= 0V
= 1A
FB
FB
A
Switch V
I
80
mV
μA
mV
μA
V
mA
V
mV
nA
%
CESAT
SW
Switch Leakage Current
Boost Schottky Forward Voltage
Boost Schottky Reverse Leakage
Minimum Boost Voltage (Note 5)
BOOST Pin Current
EN Voltage Threshold
EN Voltage Hysteresis
EN Pin Current
PG Threshold Offset from V
0.02
730
0.02
1.3
20
1.02
60
1
I
= 100mA
SH
V
= 12V
2
1.8
32
REVERSE
l
l
I
= 1A, V
– V = 3V
SW
BOOST
SW
EN Falling, V ≥ 4.3V
0.92
5
1.12
IN
0.2
8.4
20
13
V
Falling
FB
FB
PG Hysteresis as % of Output Voltage
PG Leakage
PG Sink Current
SYNC Low Threshold
SYNC High Threshold
SYNC Pin Current
1.7
%
V
V
= 3V
= 0.4V
0.02
480
1.0
1.18
0.1
1
µA
μA
V
V
nA
μA
PG
PG
l
125
0.6
1.5
2.6
V
V
= 6V
SYNC
SS Source Current
= 0.5V
0.9
1.8
SS
Note 3: Minimum input voltage depends on application circuit.
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 4: The LT3975 contains circuitry that extends the maximum duty
cycle if there is sufficient voltage across the boost capacitor. See the
Application Information section for more details.
Note 2: The LT3975E 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
LT3975I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3975H 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
Note 5: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the switch.
Note 6: 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
when overtemperature protection is active. Continuous operation above
the specified maximum operating junction temperature may impair device
reliability or permanently damage the device.
temperatures greater than 125°C. The junction temperature (T , in °C) is
J
calculated from the ambient temperature (T , in °C) and power dissipation
A
(P , in Watts) according to the formula:
D
T = T + (P • θ )
JA
J
A
D
where θ (in °C/W) is the package thermal impedance.
JA
3975f
3
Linear [ Linear ]
