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PDF LT3741-1 Data sheet ( Hoja de datos )
| Número de pieza | LT3741-1 | |
| Descripción | Step-Down Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LT3741/LT3741-1
High Power, Constant
Current, Constant Voltage,
Step-Down Controller
FEATURES
nn Control Pin Provides Accurate Control of Regulated
Output Current
nn ±1.5% Voltage Regulation Accuracy
nn ±6% Current Regulation Accuracy
nn 6V to 36V Input Voltage Range
nn Wide Output Voltage Range Up to (VIN – 2V)
nn Average Current Mode Control
nn <1µA Shutdown Current
nn Up to 94% Efficiency
nn Additional Pin for Thermal Control of Load Current
nn Thermally Enhanced 4mm × 4mm QFN and 20-Pin
FE Package
APPLICATIONS
nn General Purpose Industrial
nn Super-Cap Charging
nn Applications Needing Extreme Short-Circuit Protec-
tion and/or Accurate Output Current Limit
nn Constant Current or Constant Voltage Source
DESCRIPTION
The LT®3741 and LT3741-1 are fixed frequency synchro-
nous step-down DC/DC controllers designed to accurately
regulatetheoutputcurrentatupto 20A.Theaveragecurrent-
mode controller will maintain inductor current regulation
over a wide output voltage range of 0V to (VIN – 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.
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
RHOT
45.3k
39.2k
5.6nF
RNTC
10nF
EN/UVLO
RT
SYNC
LT3741
VIN
HG
VREF
CBOOT
CTRL1
VC
SW
VCC_INT
CTRL2
SS
LG
GND
SENSE+
SENSE–
FB
1µF
220nF
22µF
VIN
100µF 14V TO 36V
2.2µH 2.5mΩ
VOUT
10V
20A
150µF
×2
88.7k
12.1k
3741 TA01a
For more information www.linear.com/LT3741
VOUT vs IOUT
12
10
8
6
4
2 VIN = 18V
VOUT = 10V
0 ILIMIT = 20A
0246
8 10 12 14 16 18 20 22
IOUT (A)
3741 TA01b
37411ff
1
1 page  
TYPICAL PERFORMANCE CHARACTERISTICS
VREF Pin Voltage
2.06
2.05
2.04
VIN = 36V
2.03
2.02 VIN = 6V
2.01
2.00
1.99
1.98
–50
–15 20 55 90 125
TEMPERATURE (°C)
3741 G05
Soft-Start Pin Current
14
13
12
VIN = 36V
11
VIN = 6V
10
9
8
7
6
–50 –15
20
55
90 125
TEMPERATURE (°C)
3741 G09
VREF Current Limit
1.6
1.4
TA = 25°C
TA = 130°C
1.2
TA = –50°C
1.0
0.8
6
12 18 24
VIN (V)
VCC_INT Current Limit
6
30 36
3741 G06
5
4
3
2
1
VIN = 12V
0 TA = 25°C
0 10
20 30 40
ILOAD (mA)
50 60
3741 G07
CBOOT-SW UVLO Voltage
3.00
2.75
2.50
2.25
2.00
1.75
1.50
–50
–15 20 55 90 125
TEMPERATURE (°C)
3741 G11
VCC_INT UVLO
4.00
3.75
3.50
3.25
3.00
2.75
2.50
–50
–15 20 55 90 125
TEMPERATURE (°C)
3741 G12
LT3741/LT3741-1
RT Pin Current Limit
90
80
70
60
50
40
–50
–15 20 55 90 125
TEMPERATURE (°C)
3741 G08
Internal UVLO
5.0
4.5
4.0
3.5
3.0
–50
–15 20 55 90 125
TEMPERATURE (°C)
3741 G10
VCC_INT Load Reg at 12V
6.0
5.6
5.2
25°C
4.8
4.4
4.0
0
10 20 30 40 50 60
ILOAD (mA)
3741 G13
For more information www.linear.com/LT3741
37411ff
5
5 Page 
LT3741/LT3741-1
BLOCK DIAGRAM (QFN Package)
VIN
402k
133k
100nF
EN/UVLO
1
2 VREF
SYNC
82.5k
13 SYNC
12 RT
2V REFERENCE
OSCILLATOR
100nF
40.2k
5.6µF
1.5V
5 CTRL1
+
+
6 SS
3 CTRL2
10 VC
–
CTRL BUFFER
11µA
VIN 20
INTERNAL
REGULATOR
AND
UVLO
VCC_INT 19
–
+
PWM
COMPARATOR
RQ
S
HIGH SIDE
DRIVER
SYNCRONOUS
CONTROLLER
CBOOT 17
HG 15
SW 16
LG 18
ZERO CROSS
COMPARATOR
LOW SIDE
DRIVER
+–
SENSE+ 8
CURRENT
MIRROR
gm AMP
gm = 475µA/V
RO = 3.5M
IOUT = 40µA
3k SENSE– 9
90k
VOLTAGE
1.21V
REGULATOR
AMP
gm = 850µA/V
FB 7
3741 F01
1µF 47µF VIN
10µF
0.1µF
2.4µH
RS
5mΩ
VOUT
150µF
×2
40.2k
10k
Figure 2. Block Diagram, LT3741-1
For more information www.linear.com/LT3741
37411ff
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LT3741-1.PDF ] | |
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