Datasheet

LT3689/LT3689-5
4
3689fe
For more information www.linear.com/LT3689
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
t
UV
UV Detect to RST Asserted Step V
FB
from 0.9V to 0.5V
l
10 30 65 µs
WDI Input Threshold
l
0.4 0.95 1.15 V
WDI Input Pull-Up Current –2 µA
WDI Input Pulse Width
l
300 ns
W/T Threshold Voltage
l
0.4 0.8 1 V
W/T Input Pull-Down Current 2.6 µA
WDE Threshold Voltage
l
0.4 0.8 1 V
WDO Pull-Up Current (Note 6) –0.6 –0.85 µA
RST Pull-Up Current (Note 6) –0.6 –0.85 µA
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: Absolute maximum voltage at V
IN
and EN/UVLO pins is 60V for
nonrepetitive 1 second transients, and 36V for continuous operation.
Note 3: The LT3689E 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
LT3689I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3689H 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 4: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at higher duty cycles.
Note 5: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 6: The output of RST and WDO has a weak pull-up to V
OUT
of
typically 1µA. However, external pull-up resistors may be used when faster
rise times are required or for V
OH
higher than V
OUT
.
Note 7: Polarity specification for all currents into pins is positive. All
voltages are referenced to GND unless otherwise specified.
Note 8: For the LT3689-5, V
OUT
is set to 5.5V to ensure the switching.
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
OUT
= 5V, unless otherwise noted. (Note 3)
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency, V
OUT
= 5V Efficiency, V
OUT
= 3.3V Efficiency, V
OUT
= 1.8V
LOAD CURRENT (A)
0
EFFICIENCY (%)
0.4
0.2
0.60.3
0.1
0.5 0.7
3689 G01
T
A
= 25°C
f = 1MHz
V
IN
= 12V
V
IN
= 24V
V
IN
= 32V
85
90
80
75
70
65
95
0
0.4
0.2
0.60.3
0.1
0.5 0.7
LOAD CURRENT (A)
EFFICIENCY (%)
85
80
75
70
65
90
3689 G02
T
A
= 25°C
f = 700kHz
V
IN
= 12V
V
IN
= 24V
V
IN
= 32V
LOAD CURRENT (A)
EFFICIENCY (%)
70
75
65
60
55
50
80
3689 G03
T
A
= 25°C
f = 1MHz
V
IN
= 5V
V
IN
= 12V
0
0.4
0.2
0.60.3
0.1
0.5 0.7