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DC1602A

P1-P3P4-P6
1
dc1602af
DEMO MANUAL DC1602A
Description
LT3741
High Power Constant Current, Constant
Voltage Synchronous Buck Controller
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 demon
-
strate 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
performance summary
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.
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
PV
IN
* Input Supply Range. PV
IN
= V
IN
L1 is Optimized for 12V. 12 24 V
V
OUT
* Output Voltage With ONE PT120 LED. 6V Is the Overvoltage
Limit
4.5 6 V
I
OUT
Output Current In Current Mode 18.8 20 21.2 A
V
OUT
Output Voltage In Voltage Mode 5.88 6 6.12 V
F
SW
Switching Frequency R3 = 100k 380 420 460 kHz
EFE Efficiency at DC V
IN
= 12V, V
OUT
= 5V, I
OUT
= 20A 94 %
* PV
IN
and V
IN
of the demo circuit are limited to 24V typical by the selection of MOSFETs. The LT3741 input range is 6V to 36V. V
OUT
maximum of the
demo circuit is limited to 6V due to the selection of the output capacitors.
2
dc1602af
DEMO MANUAL DC1602A
Quick start proceDure
Demonstration circuit 1602A is easy to set up to evalu-
ate 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
PV
IN
and GND. The input power supply should have a
current limit of 10A or more.
2. With power off, connect a LED between V
OUT
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.
Figure 1. Proper Measurement Equipment Setup
DC1602 F01
LOAD
+–
+
–
+
–
3
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
P1-P3P4-P6

DC1602A

Mfr. #:
Buy DC1602A
Manufacturer:
Analog Devices Inc.
Description:
Power Management IC Development Tools LT3741EFE Demo Board - High Power Consta
Lifecycle:
New from this manufacturer.
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