LT3641
4
3641fa
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 LT3641E is guaranteed to meet performance specifi cations
from 0°C to 125°C junction temperature. Specifi cations over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3641I is guaranteed and tested over the full –40°C to 125°C operating
junction temperature range. The LT3641H is guaranteed and tested over
the full –40°C to 150°C operating junction temperature range.
Note 3: SW1, SW2 current limit is guaranteed by design and/or correlation
to static test. Slope compensation reduces current limit at higher duty
cycle.
PARAMETER CONDITIONS MIN TYP MAX UNITS
SS1, SS2 Charge Current SS1 = 0.5V, SS2 = 0.5V 1.3 2.0 2.7 μA
SS1 to FB1 Offset Voltage SS1 = 0.6V 5 30 mV
SS2 to FB2 Offset Voltage SS2 = 0.3V 5 30 mV
RST1 Threshold as Percentage of V
FB1
l
90 92 94 %
RST2 Threshold as Percentage of V
FB1
l
88 91 94 %
Undervoltage to RST Assert Time 20 μs
RST1, RST2, WDO Pull-Up Current RST1, RST2, WDO = 0V 5 15 30 μA
RST1, RST2, WDO Output Voltage I
RST1
, I
RST2
, I
WDO
= 2mA 150 250 mV
RST1, RST2 Timeout Period (t
RST
) CPOR = 220pF
l
8 9.5 11 ms
Watchdog Start Delay Time (t
DLY
) CWDT = 820pF 14 16 18 ms
Watchdog Upper Boundary (t
WDU
) CWDT = 820pF
l
27 32 35 ms
Watchdog Lower Boundary (t
WDL
) CWDT = 820pF
l
1.68 2 2.2 ms
WDI Pull-Up Current WDI = 1.2V 4 μA
WDI Voltage Threshold 0.55 0.85 1.15 V
WDI Low Minimum Pulse Width 300 ns
WDI High Minimum Pulse Width 300 ns
WDE Pull-Down Current WDE = 2V 1 μA
WDE Threshold
l
0.5 0.7 0.9 V
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 12V, V
IN2
= 3.3V, EN/UVLO = 12V, EN2 = 3.3V, unless otherwise noted.
Note 4: The oscillator cycle is extended when DA current exceeds its limit.
DA current limit is fl at over duty cycle.
Note 5: If the SW2 NMOS current exceeds its limit at the start of an
oscillator cycle, the PMOS will not be turned on in the cycle.
Note 6: The QFN switch R
DS(ON)
is guaranteed by correlation to wafer level
measurement.
Note 7: Absolute Maximum Voltage at V
IN
and EN/UVLO pins is 55V for
nonrepetitive 1 second transients, and 42V for continuous operation.
Note 8: 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 specifi ed maximum operating junction temperature may impair device
reliability.
ELECTRICAL CHARACTERISTICS
