LT3741/LT3741-1
1
37411ff
For more information www.linear.com/LT3741
TYPICAL APPLICATION
DESCRIPTION
High Power, Constant
Current, Constant Voltage,
Step-Down Controller
The LT
®
3741 and LT3741-1 are fixed frequency synchro-
nous step-down DC/DC controllers designed to accurately
regulate the output current at up to 20A. The average current-
mode controller will maintain inductor current regulation
over a wide output voltage range of 0V to (V
IN
– 2V). The
regulated current is 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. If sinking current is not required, or for parallel
applications, use the LT3741-1. The regulated voltage and
overvoltage protection are set with a voltage divider from
the output to the FB pin. Soft-Start is provided 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.
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.
10V/20A Constant Current, Constant Voltage Step-Down Converter
FEATURES
APPLICATIONS
n
Control Pin Provides Accurate Control of Regulated
Output Current
n
±1.5% Voltage Regulation Accuracy
n
±6% Current Regulation Accuracy
n
6V to 36V Input Voltage Range
n
Wide Output Voltage Range Up to (V
IN
– 2V)
n
Average Current Mode Control
n
<1µA Shutdown Current
n
Up to 94% Efficiency
n
Additional Pin for Thermal Control of Load Current
n
Thermally Enhanced 4mm × 4mm QFN and 20-Pin
FE Package
n
General Purpose Industrial
n
Super-Cap Charging
n
Applications Needing Extreme Short-Circuit Protec-
tion and/or Accurate Output Current Limit
n
Constant Current or Constant Voltage Source
EN/UVLOEN/UVLO
HG
V
IN
CBOOT
V
REF
VC
CTRL1
CTRL2
LT3741
RT
SYNC
SW
LG
GND
SENSE
+
SENSE
–
V
CC_INT
220nF
2.2µH
22µF
2.5mΩ
FB
10nF
39.2k
5.6nF
82.5k
88.7k
12.1k
150µF
×2
R
NTC
100µF
V
IN
14V TO 36V
V
10V
20A
1µF
SS
R
HOT
45.3k
I
OUT
(A)
0 2 4 6 8 10 12 14 16 18
OUT
6
8
10
4
2
0
20
V
IN
= 18V
V
OUT
= 10V
I
LIMIT
= 20A
V
OUT
vs I
OUT
L, LT , LT C , LT M , 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.
