DC1930A - Demo Manual

DEMO MANUAL DC1930A
LT3744
High Current Synchronous
Inverting Buck-Boost LED Driver
DESCRIPTION
Demonstration circuit 1930A is a high current synchronous
inverting buck-boost LED driver featuring the LT®3744. The
unique drive stage used on the LT3744 allows the anodes of
three LEDs to be connected together for better heat sinking
in both the step-down configuration and the inverting buckboost configuration. The pros and cons of 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
and PWM dimming for a 12V input. Each of the 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
PERFORMANCE SUMMARY
SYMBOL
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 measured 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
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 TA = 25°C
PARAMETER
CONDITIONS
PVIN*
Input Supply Voltage
LED Voltage = 5V
VLED+ to VLED–
Maximum Output Voltage
IOUT
Output Current
FSW
Switching Frequency
MIN
7
Efficiency at DC
MAX
30
6.05
CTRL1, CTRL2, CTRL3 = 1.5V
11.4
270
VIN = 12V, IOUT = 12A, VOUT = 4V
*The board operating voltage range is narrower than the IC operating range in an inverting buck-boost configuration.
EFF
TYP
UNITS
V
V
12
12.6
A
300
330
kHz
89.3
%
dc1930af
1
DEMO MANUAL DC1930A
DESCRIPTION
LED CURRENT
5A/DIV
SW VOLTAGE
5V/DIV
DC1930A F01
Figure 1: DC1930A Current Rise Time: VIN = 12V, LED Voltage = 4.2V when ON. Total LED Current = 12A
QUICK START PROCEDURE
Demonstration circuit 1930A is easy to set up to evaluate 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.
2
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.
dc1930af
DEMO MANUAL DC1930A
QUICK START PROCEDURE
Figure 2. Proper Measurement Equipment Setup
dc1930af
3
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
4
dc1930af
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
E1
C27
1nF
SYNC
PWM3
PWM2
PWM1
CTRL3
CTRL2
CTRL1
EN/UVLO
R21
100K
R22
100K
2
R8
R16
C26
R9
E8
1nF
82.5K
OPT
100K
0805
C7
1uF
50V
7
5
4
2
6
3
1
36
E9
R17
309K
E7
E14
5
D5
SBR1A40S3
1
143K
(300kHz)
R25
13
14
11
VIN
RT
SS
FAULT
SYNC
PWM3
PWM2
PWM1
CTRL3
CTRL2
CTRL1
CTRLT
VREF
EN/UVLO
VIN
U1
LT3744EUHE
C24
10uF
50V
1210
1. ALL RESISTORS ARE 0603.
ALL CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
R19
309K
R23
100K
C18 10nF
10
9
R20
100K
C14
2.2uF
SGND
100K
R3
R33
0
8
C29
1nF
R7
100K
OPT
R2
C1
C2
10uF
50V
1210
E13
R18
309K
R10
100K
C4
56uF,50V
50HVT56M
E12
C28
1nF
R6
100K
E16
E15
E2
E10
E6
E4
E11
SGND
SGND
SGND
J2
BANANA JACK
SGND
+
4
C25
10uF
50V
1210
C5
OPT
C23
33nF
C22
33nF
C21
33nF
R31
0
R30
0
R29
0
+
29
J1
BANANA JACK
12
SGND
31
0
ISN
ISP
VF NEG
BG
SW
INTVCC
LED_ISN
LED_ISP
FB
PWM_OUT3
PWM_OUT2
C8
22uF
6.3V
0805
C6
0.22uF
4
PWM3
15
16
17
PWM2
0
R13
PWM1
0
R12
23
4
25
C17
OPT
R36
0
27
21
22
24
32
Q3 Q5
BSC026N04LS
30
34
D1
PMEG4002EB
R4
0
R1
PWM_OUT1
BOOST
2
1
5
6
7
8
L1
0.82uH
3
D3-1
BAT54A
D2
OPT
DI123
KRL6432
R5
0.003
Q1
Q2
BSC035N04LS G
744355182
1
2
3
5
6
7
8
1
2
3
PVIN
3 D3-2
BAT54A
4
2
2
1
3
*
+
Q6
4
2
D4-2
BAT54A
3
2
Si7234DP
8
7
5
6
C10
OPT
C11
470uF
1
3
PVIN
3.3V - 36V
3
1
+
2
R32
0.005
KRL6432
4
2
D4-1
BAT54A
3
1
Si7234DP
Q4
8
7
5
6
C15
OPT
C12
470uF
2
1
3
3
+
Si7234DP
Q7
8
7
5
6
C13
OPT
C16
470uF
R27
1K
R14
4.02K
4
Q8
C19
1nF
J6
LED1-
LED+
J3
BSC010N04LS
PWM1
C9
10uF
1206
5
6
7
8
1
2
3
D
4
4
Q9
BSC010N04LS
PWM2
J7
LED2-
LED+
J4
1
5
6
7
8
1
4
J8
LED3-
LED+
J5
Q10
BSC010N04LS
PWM3
1
2
3
* SEE DEMO MANUAL
VEE
28
VEE
26
VEE
33
VEE
35
VEE
37
VC1
20
TG
VC2
19
VC3
18
5
6
7
8
1
2
3
5
E5
E3
VEE
LED+
A
B
C
D
DEMO MANUAL DC1930A
SCHEMATIC DIAGRAM
dc1930af
5
DEMO MANUAL DC1930A
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
dc1930af
Linear Technology Corporation
LT 1215 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2015
Similar pages