DC1602A - Demo Board

DEMO MANUAL DC1602A
LT3741
High Power Constant Current, Constant
Voltage Synchronous Buck Controller
Description
Demonstration circuit 1602A is a high power constant
current, constant voltage synchronous buck controller
featuring the LT®3741. The demo board is optimized for
20A output from a 12V input. Being an LED driver, the
output current is being regulated until the output voltage
reaches a programmed voltage limit. The voltage limit on
this demo board is set to around 6V by R11 and R14. The
6V is chosen because of the 10V voltage rating of the output
capacitors. Higher output voltage can be easily achieved
with higher voltage rated output capacitors. The ideal load
to be used with this demo board is a single LED, such as
PT120 from Luminus Devices. Smaller LEDs may not be
able to handle the high current, even for a short period of
time. At 20A, the demo circuit can operate continuously.
However, it is necessary to mount the LED load on a proper
heat sink and possibly with a fan to avoid exceeding its
maximum temperate rating.
The input voltage range of the LT3741 itself is 6V to 36V.
However, the demo board utilizes 30V MOSFETs to demonstrate best efficiency, so the maximum recommended input
voltage is 24V for the demo board. The typical efficiency
of the demo board is 94% from a 12V input to 5V, 20A
load. The lower the input voltage, the higher the efficiency
tends to be with a given load. At output power level of
100W, a couple of percent of efficiency improvement is
a huge advantage in minimizing temperature rise. If an
efficiency measurement is needed in an application, the
output voltage must be measured at the output capacitors
instead of at the LED load. This prevents cable loss from
being counted as a loss of the board. Output current can
be adjusted by varying the CTRL1 voltage.
R16 can be used to slow down the gate drive. Slower gate
drive helps to reduce ringing on the SW node without
noticeable effect on the efficiency. A 10Ω is usually more
than enough to completely damp any ringing.
R10, R13 and C14 help filtering out voltage spikes seen
on the SENSE+ or SENSE– pin. It is critical to have those
components on a board.
The LT3741 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1602A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1602A.
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.
Performance Summary
Specifications are at TA = 25°C
SYMBOL
PARAMETER
CONDITIONS
TYP
MAX
PVIN*
Input Supply Range. PVIN = VIN
L1 is Optimized for 12V.
12
24
V
VOUT*
Output Voltage
With ONE PT120 LED. 6V Is the Overvoltage
Limit
4.5
6
V
IOUT
Output Current
In Current Mode
18.8
20
21.2
A
VOUT
Output Voltage
In Voltage Mode
5.88
6
6.12
V
FSW
Switching Frequency
R3 = 100k
380
420
460
kHz
EFE
Efficiency at DC
VIN = 12V, VOUT = 5V, IOUT = 20A
MIN
UNITS
94
%
* PVIN and VIN of the demo circuit are limited to 24V typical by the selection of MOSFETs. The LT3741 input range is 6V to 36V. VOUT maximum of the
demo circuit is limited to 6V due to the selection of the output capacitors.
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1
DEMO MANUAL DC1602A
Quick Start Procedure
Demonstration circuit 1602A is easy to set up to evaluate the performance of the LT3741. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to
PVIN and GND. The input power supply should have a
current limit of 10A or more.
–
+
+
–
2. With power off, connect a LED between VOUT and GND.
3. Turn on the power at the input. Be careful not to look
at a powered LED directly.
4. Carefully evaluate other design parameters as needed.
5. Adjust CTRL1 to change output current.
6. To modify the demo board for other applications, please
contact Linear Applications Group for help.
–
LOAD
+
DC1602 F01
Figure 1. Proper Measurement Equipment Setup
2
dc1602af
DEMO MANUAL DC1602A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP., ALUM., ELECT., 100µF, 50V
SUN ELECT., 50CE100LX
2
4
C2, C3, C4, C5
CAP., X7R, 4.7µF, 50V, 10%, 1210
MURATA, GRM32ER71H475KA88L
3
2
C8, C10
CAP., POSCAP, 150µF, 10V
SANYO, 10TPF150ML
4
1
C6
CAP., X7R, 1µF, 50V, 10%, 0805
MURATA, GRM21BR71H105KA12L
5
1
C7
CAP., X7R, 0.22µF, 10V, 10%, 0603
MURATA, GRM188R71A224KA01D
6
2
C9, C11
CAP., X5R, 47µF, 16V, 10%, 1210
MURATA, GRM32ER61C476KE15L
7
1
C12
CAP., X5R, 22µF, 6.3V, 20%, 0805
MURATA, GRM21BR60J226ME39L
8
1
C13
CAP., COG, 2nF, 50V, 0603
MURATA, GRM1885C1H202JA01D
9
1
C14
CAP., NPO, 33nF, 16V, 0603
MURATA, GRM188R71C333KA01D
10
1
C15
CAP., X7R, 10000pF, 16V, 0603
MURATA, GRM188R71C103KA01D
11
1
C17
CAP., U2J, 5100pF, 50V, 0603
MURATA, GRM1887U1H512JA01D
12
1
D1
1.0A LOW VF SCHOTTKY RECTIFIER
DIODES INC., DFLS140
13
1
D2
2.0A LOW VF SCHOTTKY RECTIFIER
DIODES INC., DFLS240L
14
1
L1
INDUCTOR, 1.3µH
WE., 7443551130
15
2
Q1, Q2
MOSFET, N-CHANNEL, PG-TDSON-8
INFINEON, BSC080N03LS G
16
1
Q3
MOSFET, N-CHANNEL, PG-TDSON-8
INFINEON, BSC011N03LSI
17
1
R1
RES., CHIP, 374k, 1%, 0603
VISHAY, CRCW0603374KFKEA
18
1
R2
RES., CHIP, 124k, 1%, 0603
VISHAY, CRCW0603124KFKEA
19
3
R3, R5, R8
RES., CHIP, 100k, 1%, 0603
VISHAY, CRCW0603100KFKEA
20
1
R4
RES., CHIP, 0.0025, 1W, 1%, 2512
VISHAY, WSL25122L500FEA
21
1
R7
RES., CHIP, 45.3k, 1%, 0603
VISHAY, CRCW060345K3FKEA
22
2
R10, R13
RES., CHIP, 10Ω, 1%, 0603
VISHAY, CRCW060310R0FKEA
23
1
R11
RES., CHIP, 40.2k, 1%, 0603
VISHAY, CRCW060340K2FKEA
24
1
R12
RES., CHIP, 680k, 1%, 0603
VISHAY, CRCW0603680KFKEA
25
1
R14
RES., CHIP, 10k, 1%, 0603
VISHAY, CRCW060310K0JNEA
26
1
R15
RES., CHIP, 66.5k, 1%, 0603
VISHAY, CRCW060366K5FKEA
27
1
U1
I.C. LT3741EFE, 20-PIN TSSOP
LINEAR TECH., LT3741EFE#PBF
dc1602af
3
DEMO MANUAL DC1602A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Additional Demo Board Circuit Components
1
0
C16, C18
CAP., 0603, OPT
2
0
Q4
MOSFET, OPT
3
1
R16
RES., CHIP, 0Ω, 0603
4
0
R9, R17
RES., 1206, OPT
VISHAY, CRCW06030000Z0ED
Hardware: For Demo Board Only
1
4
E1, E2, E4, E5
JACK, BANANA
KEYSTONE, 575-4
2
6
E3, E6, E7, E8, E9, E10
TURRET, TESTPOINT , 091"
MILL MAX 2501-2-00-80-00-00-07-0
3
4
STAND-OFF
STAND-OFF, NYLON, 0.5" tall
KEYSTONE, 8833(SNAP ON)
4
dc1602af
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
A
B
C
D
VIN *
CTRL2
CTRL1
SYNC
EN/UVLO
GND
GND
6V - 36V
E7
E6
E8
E3
E9
5
E2
E1
R2
124K
C1
100uF,50V
50CE100LX
R12
680K
R7
45.3K
C2
C3
4.7uF
1210
C15
10nF
R8
100K
C17
5nF
R9
OPT
R5
100K
R3
100K
- SEE QUICK START GUIDE
1. ALL RESISTORS ARE IN OHMS, 0603.
ALL CAPACITORS ARE IN MICROFARADS, 0603.
*
4
NOTE: UNLESS OTHERWISE SPECIFIED
C13
2nF
R1
374K
VIN
+
4
C6
1uF
50V
0805
VC
SS
CTRL2
CTRL1
VREF
SYNC
RT
EN/UVLO
R15
66.5K
13
9
6
8
5
15
14
4
LT3741EFE
U1
C4
C5
4.7uF
1210
VIN
FB
SENSEN
SENSEP
LG
SW
VCC_INT
CBOOT
HG
10
12
11
20
18
1
19
17
D1
DFLS140
C18
OPT
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
2
2
SCALE = NONE
C9
C11
47uF
1210
__
ECO
2-1
2
DESCRIPTION
R14
10k
C8
C10
150uF
OPT
C16
GND
GND
20A @ 6V
VOUT *
1-6-16
WALKER B.
WALKER B.
DATE
02-02-10
APPROVED
DATE:
N/A
SIZE
1
DEMO CIRCUIT 1602A
Thursday, January 07, 2016
IC NO.
SHEET 1
2-1
OF 1
REV.
HIGH POWER CONSTANT CURRENT,
CONSTANT VOLTAGE SYNCHRONOUS BUCK CONTROLLER
LT3741EFE
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
R11
40.2K
E10
E5
E4
REBUILD CHANGED Q1,Q2,Q3
PRODUCTION
1
REVISION HISTORY
TECHNOLOGY
REV
TITLE: SCHEMATIC
R4
0.0025
2512
WALKER B.
A.K.
APPROVALS
L1
1.3uH
WE 7443551130
D2
DFLS240L
R17
OPT
1206
CUSTOMER NOTICE
R13 10
R10 10
4
C12
22uF
0805
VIN
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
APP ENG.
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
C14
33nF
4
C7
0.22uF
Q3
BSC011N03LSI
Q4
OPT
R16
0
Q1
Q2
BSC080N03LS G
3
2
1
3
VIN
21
GND
16
7 GND
2 GND
GND
2
1
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
A
B
C
D
DEMO MANUAL DC1602A
Schematic Diagram
dc1602af
5
DEMO MANUAL DC1602A
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
6
dc1602af
Linear Technology Corporation
LT 0416 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2016
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