LT3741 Datasheet, PDF (1/24 Pages) Linear Technology – High Power, Constant Current, Constant Voltage, Step-Down Controller

LT3741
High Power, Constant
Current, Constant Voltage,
Step-Down Controller
Features
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 (VIN – 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
Applications
n _{General Purpose Industrial}
n _{Super-Cap Charging}
n _{Applications Needing Extreme Short-Circuit}
Protection and/or Accurate Output Current Limit
n _{Constant Current or Constant Voltage Source}
Description
The LT^®3741 is a fixed frequency synchronous step-down
DC/DC controller 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. 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.
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.
Typical Application
10V/20A Constant Current, Constant Voltage Step-Down Converter
EN/UVLO
82.5k
10nF
R_HOT
45.3k
39.2k
5.6nF
R_NTC
10nF
EN/UVLO
V_IN
RT
SYNC
LT3741 ^HG
V_REF
CBOOT
CTRL1
VC
SW
V_{CC_INT}
CTRL2
SS
LG
GND
SENSE⁺
SENSE^–
FB
1µF
220nF
22µF
V_IN
14V TO 36V
100µF
2.2µH _2.5mΩ
V_OUT
10V
20A
150µF
s2
88.7k
12.1k
3741 TA01a
V_OUT vs I_OUT
12
10
8
6
4
2 ^VIN ^{= 18V}
V_OUT = 10V
I_LIMIT = 20A
0
0246
8 10 12 14 16 18 20 22
I_OUT (A)
3741 TA01b
3741f