LT3741
High Power, Constant
Current, Constant Voltage,
Step-Down Controller
FeaTures
DescripTion
The LT®3741 is a fixed frequency synchronous step-down
DC/DCcontrollerdesignedtoaccuratelyregulatetheoutput
current at up to 20A. The average current-mode controller
willmaintaininductorcurrentregulationoverawideoutput
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Control Pin Provides Accurate Control of Regulated
Output Current
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1.5% Voltage Regulation Accuracy
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±±% Current Regulation Accuracy
6V to 36V Input Voltage Range
Wide Output Voltage Range Up to (V – 2V)
Average Current Mode Control
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voltage range of 0V to (V – 2V). The regulated current is
IN
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set by an analog voltage on the CTRL pins and an external
sense resistor. Due to its unique topology, the LT3741 is
capable of sourcing and sinking current. The regulated
voltage and overvoltage protection are set with a voltage
dividerfromtheoutputtotheFBpin.Soft-Startisprovided
to allow a gradual increase in the regulated current during
startup. The switching frequency is programmable from
200kHz to 1MHz through an external resistor on the RT
pin or through the use of the SYNC pin and an external
clock signal.
IN
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<1µA Shutdown Current
Up to 94% Efficiency
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Additional Pin for Thermal Control of Load Current
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Thermally Enhanced 4mm × 4mm QFN and 20-Pin
FE Package
applicaTions
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General Purpose Industrial
Additional Features include an accurate external reference
voltage for use with the CTRL pins, an accurate UVLO/EN
pin that allows for programmable UVLO hysteresis, and
thermal shutdown.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 7199560, 7321203 and others pending.
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Super-Cap Charging
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Applications Needing Extreme Short-Circuit
Protection and/or Accurate Output Current Limit
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Constant Current or Constant Voltage Source
Typical applicaTion
10V/20A Constant Current, Constant Voltage Step-Down Converter
VOUT vs IOUT
V
IN
V
EN/UVLO
82.5k
EN/UVLO
RT
SYNC
IN
14V TO 36V
12
10
8
1µF
100µF
HG
LT3741
220nF
V
REF
CBOOT
SW
2.2µH
V
10V
20A
2.5mΩ
10nF
OUT
CTRL1
VC
6
V
CC_INT
22µF
39.2k
5.6nF
4
R
LG
HOT
150µF
s2
45.3k
GND
V
V
I
= 18V
2
IN
OUT
+
–
CTRL2
SS
SENSE
SENSE
= 10V
= 20A
88.7k
12.1k
LIMIT
0
R
NTC
FB
0
2
4
6
8
10 12 14 16 18 20 22
(A)
10nF
I
OUT
3741 TA01b
3741 TA01a
3741f
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