Linear Technology DC1930A Quick setup guide

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DEMO MANUAL DC1930A
DESCRIPTION
LT3744
High Current Synchronous
Inverting Buck-Boost LED Driver
Demonstrationcircuit1930Ais a high currentsynchronous
invertingbuck-boost LED driver featuring the LT
®
3744. The
uniquedrivestageused on theLT3744allows the anodesof
three LEDs to be connected together for better heat sinking
inboththestep-downconfigurationandtheinvertingbuck-
boost configuration.The prosand consof each configuration
can be found in the data sheet. This demonstration circuit
1930A is for customers to test the inverting buck-boost
configuration. The step-down configuration is shown in a
separate demonstration circuit DC2339A.
The components are optimized for the efficiency, thermal
andPWMdimmingfora12V input. Each ofthe three outputs
is up to 5V, 12A with a 6.05V maximum output voltage
limit. The PWM1, PWM2 and PWM3 pins are set to low
by default. A DC or PWM signal is required to connect to
at least one of the PWM pins to enable the circuit. At any
giving time, output current only passes through one LED
determined by settings of PWM pins.
The CTRL1, CTRL2 and CTRL3 pins can be adjusted to
provide accurate analog dimming down to 20:1 ratio.
The input voltage range for the LT3744 to operate is from
3.3V to 36V. However, to maintain the output current
regulation in an inverting buck-boost regulator, the actual
input voltage range is determined by the load current,
voltage, the maximum duty cycle, etc. For a 5V, 12A load,
the demo board operating input range should limit to 7V
to 30V at room temperature. The load to be used with this
demo board is high current LEDs or laser diodes. Smaller 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
LEDs may not be able to handle the high current, even for
a short period of time. It is necessary to mount the LED
load on a proper heat sink. A fan may become necessary
to avoid exceeding LED’s maximum temperate rating.
The typical efficiency of the demo board is 89.3% from a
12V input to 4V, 12A load. If an efficiency measurement is
needed in an application, the output voltage must be mea-
sured at the output capacitors instead of the LED load. This
prevents cable loss from being counted as loss of the board.
The demo circuit DC1930A achieves fast current rise time
from 0A to 12A in 5μs. To see the real rise time, wires
between the LED and the board should be as short as
possible to minimize the wire inductance and resistance. It
is recommended to measure the voltage across R32 with
a short 50Ω coax cable directly into a BNC connector on
the oscilloscope. Figure 1 shows the current rise time. The
current can be calculated from the measured voltage. A
current probe adds more delays to the rise time so using
a current probe is not recommended unless rise time is
not a concern.
The LT3744 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 1930A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1930A
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
PVIN* Input Supply Voltage LED Voltage = 5V 7 30 V
VLED+to VLED–Maximum Output Voltage 6.05 V
IOUT Output Current CTRL1, CTRL2, CTRL3 = 1.5V 11.4 12 12.6 A
FSW Switching Frequency 270 300 330 kHz
EFF Efficiency at DC VIN = 12V, IOUT = 12A, VOUT = 4V 89.3 %
*The board operating voltage range is narrower than the IC operating range in an inverting buck-boost configuration.
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DEMO MANUAL DC1930A
DESCRIPTION
Figure 1: DC1930A Current Rise Time: VIN = 12V, LED Voltage = 4.2V when ON. Total LED Current = 12A
Demonstration circuit 1930A is easy to set up to evalu-
ate the performance of the LT3744. Refer to Figure 2 for
proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to PVIN
and GND. Note: make sure PVIN is below 30V.
LED CURRENT
5A/DIV
SW VOLTAGE
5V/DIV
DC1930A F01
2. With power off, connect the LED load to VLED+and
proper LED1–, LED2–, LED3–according to the setting
of the PWM pins.
3. Turn on the power at the input.
4. Carefully evaluate other design parameters as needed.
QUICK START PROCEDURE
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DEMO MANUAL DC1930A
Figure 2. Proper Measurement Equipment Setup
QUICK START PROCEDURE
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DEMO MANUAL DC1930A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 4 C1, C2, C24, C25 CAP., X7R, 10µF, 50V, 10%, 1210 MURATA, GRM32ER71H106KA12L
2 1 C4 CAP., ALUM., ELECT., 56µF, 50V SUN ELECTRONIC INDUSTRIES CORP., 50HVT56M
3 1 C6 CAP., X7R, 0.22μF, 25V, 10% 0603 MURATA, GRM188R71E224KA88D
4 1 C7 CAP., X7R, 1μF, 50V, 10% 0805 AVX, 08055C105KAT2A
5 1 C8 CAP., X7R, 22μF, 6.3V, 20% 0805 AVX, 08056D226MAT2A
6 1 C9 CAP., X5R, 10μF, 25V, 20% 1206 AVX, 12063D106MAT2A
7 3 C11, C12, C16 CAP., POSCAP, 470µF, 6.3V, D4D PANASONIC, 6TPF470MAH
8 1 C14 CAP., X5R, 2.2μF, 25V, 10% 0603 MURATA, GRM188R61E225KA12D
9 1 C18 CAP., X7R, 10nF, 25V, 10% 0603 AVX, 06033C103KAT2A
10 5 C19, C26-C29 CAP., X7R, 1nF, 25V, 10% 0603 AVX, 06033C102KAT2A
11 3 C21, C22, C23 CAP., X7R, 33nF, 25V, 10% 0603 MURATA, GRM188R71E333KA01D
12 1 D1 SCHOTTKY RECTIFIER, 40V, SOD523 NXP, PMEG4002EB
13 2 D3, D4 DIODE, BAT54A SOT23 DIODES INC., BAT54A-7-F
14 1 D5 DIODE, SBR1A40S3 SOD-323 DIODES INC., SBR1A40S3-7
15 1 L1 INDUCTOR, 0.82μH WURTH ELEKTRONIK, 744355182
16 2 Q1, Q2 N-CH., 40-V, PG-TDSON-8 INFINEON, BSC035N04LS G
17 2 Q3, Q5 N-CH., 40-V, PG-TDSON-8 INFINEON, BSC026N04LS
18 3 Q4, Q6, Q7 N-CH., 12-V, POWERPAK SO-8 VISHAY, Si7234DP-T1-GE3
19 3 Q8-Q10 N-CH., 40-V, PG-TDSON-8 FL INFINEON, BSC010N04LS
20 9 R3, R6, R7, R8, R10, R20, R21, R22, R23 RES., CHIP., 100k, 1/10W, 1%0603 VISHAY, CRCW0603100KFKEA
21 9 R1, R4, R12, R13, R29-R31, R33, R36 RES., CHIP., 0Ω, 1/10W, 0603 VISHAY, CRC06030000Z0EA
22 1 R5 RES., CHIP., 0.003Ω, 3W, 1%, KRL6432 SUSUMU, KRL6432E-M-R003-F
23 1 R14 RES., CHIP., 4.02k, 1/10W, 1% 0603 VISHAY, CRCW06034K02FKEA
24 1 R16 RES., CHIP., 82.5k, 1/10W, 1% 0603 VISHAY, CRCW060382K5FKEA
25 3 R17, R18, R19 RES., CHIP., 309k, 1/10W, 1% 0603 VISHAY, CRCW0603309KFKEA
26 1 R25 RES., CHIP., 143k, 1/10W, 1% 0603 VISHAY, CRCW0603143KFKEA
27 1 R27 RES., CHIP., 1k, 1/10W, 1% 0603 VISHAY, CRCW06031K00FKEA
28 1 R32 RES., CHIP., 0.005Ω, 3W, 1%, KRL6432 SUSUMU, KRL6432D-M-R005-F
29 1 U1 I.C. LT3744EUHE 36-PIN, UHE LINEAR TECH., LT3744EUHE#PBF
Additional Demo Board Circuit Components
1 0 C5 (OPT) CAP., ALUM., ELECT.
2 0 C10, C13, C15 (OPT) CAP., D4D
3 0 C17 (OPT) CAP., 0603
4 0 D2 (OPT) DIODE, DI123
5 0 R2, R9 (OPT) RES., CHIP., 0603
Hardware For Demo Board Only
1 16 E1-E16 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0
2 8 J1-J8 JACK BANANA KEYSTONE, 575-4
3 4 (STAND-OFF) STAND-OFF, NYLON 0.50” (SNAP ON) WURTH ELEKTRONIK, 702935000
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DEMO MANUAL DC1930A
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D C C B B A A
(300kHz)
1. ALL RESISTORS ARE 0603. ALL CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
*
*
SEE DEMO MANUAL
PWM1 PWM2 PWM3
PWM1
PWM2
PWM3
E10
CTRL2
R16 82.5K
J2
SGND
BANANA JACK
C19
1nF
D3-2
BAT54A
3 2
R27
1K
E14
PWM3
E1
PVIN
E2
SGND
R10
100K
C23
33nF
R12 0
R14 4.02K
R3
100K
Q1
BSC035N04LS G
3
2
1
4
5
6
7
8
C25 1210
10uF
50V
E7
SYNC
C18 10nF
+
C15 OPT
Q5
3
2
1
4
5
6
7
8
R29
0
R2
OPT
J7
LED2-
E12
PWM1
J5
LED+
R22
100K
Q6
Si7234DP
3
4
1
27
8 6 5
C1 50V
+
C16 470uF
E9
VIN
Q8
BSC010N04LS
3
2
1
4
5
6
7
8
U1 LT3744EUHE
EN/UVLO
1
VREF
3
CTRLT
6
CTRL1
2
CTRL2
4
SS
14
FB 17
ISP 22
ISN 21
LED_ISN 15
LED_ISP 16
RT
13
SYNC
10
PWM1
7
CTRL3
5
PWM_OUT3 23
TG 29
SW 30
BOOST 31
BG 32
INTVCC 34
VIN
36
VEE
33
PWM2
8
PWM3
9
FAULT
11
VEE
35
VC1
20
VC2
19
VC3
18
VEE
26
PWM_OUT1 27
VF NEG 24
PWM_OUT2 25
VEE
28
SGND 12
VEE
37
J6
LED1-
D1
PMEG4002EB
1 2
D3-1
BAT54A
31
C17
OPT
R33 0
D4-1
BAT54A
3 1
R7
100K
R13 0
Q7 Si7234DP
3
4
1
27
8 6 5
E13
PWM2
R5
0.003
KRL6432
D2
OPT
DI123
C27 1nF
R18
309K
L1
0.82uH
744355182 C9
10uF
1206
R9 OPT
R19 309K
R1
0
E3
LED+
R21
100K
J3
LED+
R8 100K
E8
SGND
+
C4
56uF,50V
50HVT56M
R17
309K
R30
0
R4 0
Q9
BSC010N04LS
3
2
1
4
5
6
7
8
E6
CTRL1
E15
SGND
+
C10 OPT
R36
0
C2
10uF
1210
C24
1210 10uF
50V
R31
0
E16
SGND
C22
33nF
Q2
3
2
1
4
5
6
7
8
C8
22uF
6.3V
0805
+
C13 OPT
J1
PVIN
3.3V - 36V
BANANA JACK
+
C12 470uF
D4-2
BAT54A
3 2
J4
LED+
J8
LED3-
C14
2.2uF
R6
100K
E11
CTRL3
D5
SBR1A40S3
21
C26 1nF
Q4 Si7234DP
3
4
1
27
8 6 5
R23
100K
E4
EN/UVLO
R20
100K
C29 1nF
Q3
BSC026N04LS
3
2
1
4
5
6
7
8
R25
143K
C7 1uF 50V
0805
C6
0.22uF
E5
VEE
C28 1nF
+
C11 470uF
Q10
BSC010N04LS
3
2
1
4
5
6
7
8
+
C5
OPT
R32 0.005
KRL6432
C21
33nF
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DEMO MANUAL DC1930A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2015
LT 1215 • PRINTED IN USA
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
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