LT3973/LT3973-3.3/LT3973-5
4
3973fb
For more information www.linear.com/LT3973
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 LT3973E 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
LT3973I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3973H 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. The junction temperature (T
J
, in °C) is
calculated from the ambient temperature (T
A
in °C) and power dissipation
(PD, in Watts) according to the formula:
T
J
= T
A
+ (PD • θ
JA
)
where θ
JA
(in °C/W) is the package thermal impedance.
Note 3: This is the minimum input voltage for operation with accurate FB
reference voltage.
Note 4: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the switch.
Note 5: The LT3973 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 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.
EN/UVLO Pin Current V
EN/UVLO
= 12V 1 30 nA
EN/UVLO Voltage Threshold EN/UVLO Falling, V
IN
≥ 4.2V
l
1.09 1.16 1.23 V
EN/UVLO Voltage Threshold EN/UVLO Rising, V
IN
≥ 4.2V
l
1.12 1.19 1.28 V
EN/UVLO Voltage Hysteresis 30 45 mV
PG Threshold Offset from Feedback Voltage V
FB
Rising 6.5 10 13.5 %
PG Hysteresis as % of Output Voltage 0.8 %
PG Leakage V
PG
= 3V 0.01 1 µA
PG Sink Current V
PG
= 0.4V
l
220 350 µA
Minimum Switch On-Time 70 ns
Minimum Switch Off-Time (Note 5) V
IN
= 10V 130 180 ns
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
BD
= 3.3V unless otherwise noted. (Note 2)
