DEMO MANUAL DC1342B
LT3758AEMSE
High Efficiency SEPIC Converter
Description
Demonstration circuit 1342B features the
LT
®
3758AEMSE
in a 300kHz SEPIC converter circuit, designed for a 24V
output from a 18V to 72V input.
The LT3758A operates over an input range of 5.5V to 100V,
suitable for automotive, telecom and industrial applications.
It also exhibits a low shutdown current of 1µA, making it
ideal for battery-operated systems. Thanks to a novel FBX
pin architecture, the LT3758A can be connected directly to
a resistor divider from either a positive output voltage or
a negative output voltage to ground. It also packs many
popular features such as soft-start, input undervoltage
lockout, adjustable frequency and clock synchronization
in a small 10-lead MSOP package or a 3mm
×
3mm QFN
package.
The LT3758A 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 1342B.
Design files for this circuit board are available at
http://www.linear.com/demo
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
PARAMETER
Input Supply Range
Output Voltage
Maximum Output Current
Switching Frequency
300kHz SEPIC Regulator. Specifications are at T
A
= 25°C
MIN
18
23.28
24
300
TYP
MAX
72
24.72
1
UNITS
V
V
A
kHz
CONDITIONS
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DEMO MANUAL DC1342B
Quick start proceDure
Demonstration circuit 1342B is easy to set up to evaluate
the performance of the LT3758AEMSE. Refer to Figure 1
for proper measurement equipment setup and follow the
procedure below:
NOTE. When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the input or output voltage
ripple by touching the probe tip directly across the V
IN
or
V
OUT
and GND terminals. See Figure 2 for proper scope
probe technique.
1. Place JP1 on the ON position.
2. With power off, connect the input power supply to V
IN
and GND.
3. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed
the maximum input voltage.
4. Check for the proper output voltages.
NOTE. If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
Once the proper output voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
2
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DEMO MANUAL DC1342B
Quick start proceDure
+
+
POWER
SUPPLY
I
IN
–
+
V
IN
–
–
+
+
–
I
OUT
V
OUT
–
+
LOAD
–
1342B F01
Figure 1. Proper Measurement Equipment Setup
V
IN
GND
OR V
OUT
Figure 2. Measuring Input or Output Ripple
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DEMO MANUAL DC1342B
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
1
1
2
3
QTY
1
2
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
7
1
1
REFERENCE
C1
C3, C4
C5
C7
C10
C11
C12
C13
D1
L1
Q1
R1
R2, R4
R3
R5
R6
R7
R8
U1
CIN1
PART DESCRIPTION
CAP., X7R, 2.2µF, 100V, 10% 1812
CAP., TANT, 22µF, 35V, 20% 7343
CAP., X7R, 3.3µF, 25V, 20% 1210
CAP., X7R, 4.7µF, 100V, 20% 2220
CAP., X5R, 4.7µF, 10V, 20% 0805
CAP., X7R, 4.7nF, 50V, 10% 0603
CAP., C0G, 100pF, 50V, 5% 0603
CAP., X7R, 0.1µF, 25V, 10% 0603
Diodes Inc., PDS3100-13
IND., Dual, 47µH
N-MOSFET, FDMS2572, Power 56
RES., CHIP, 280k, 1/10W, 1% 0603
RES., CHIP, 20.0k, 1/10W, 1% 0603
RES., CHIP, 232k, 1/10W, 1% 0603
RES., CHIP, 0.02, 1W, 1%, 0815
RES., CHIP, 30.9k, 1/10W, 1% 0603
RES., CHIP, 42.2k, 1/10W, 1% 0603
RES., CHIP, 10k, 1/10W, 5% 0603
I.C. LT3758AEMSE, MSOP10/Exposed Pad
CAP., Alum., 10µF, 100V, E Size Code
MILL-MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM103-02-L-S
SAMTEC, 2SN-BK-G
MANUFACTURER/PART NUMBER
TDK, C4532X7R2A225K
AVX, TPSD226M035R0125
Taiyo Yuden, TMK325BJ335MN
TDK, C5750X7R2A475M
Taiyo Yuden, LMK212BJ475MG-T
TDK, C1608X7R1H472K
TDK, C1608C0G1H101J
TDK, C1608X7R1E104K
Diodes Inc., PDS3100-13
Würth Elektronik, 744870470
FAIRCHILD, FDMS2572
VISHAY, CRCW0603280KFKEA
VISHAY, CRCW060320K0FKEA
VISHAY, CRCW0603232KFKEA
THIN FILM, RL3720WTR02F-C
VISHAY, CRCW060330K9FKEA
VISHAY, CRCW060342K2FKEA
VISHAY, CRCW060310K0JNEA
LINEAR TECH.,LT3758AEMSE#TRPBF
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
E1, E2, E3, E4, E5, E6, E7 TESTPOINT, TURRET, .094" PBF
JP1
XJP1
3 PIN, 0.079 SINGLE ROW HEADER
SHUNT, .079" CENTER
4
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E1
R3
232K
R4
3
20K
D1
PDS3100
L1-1
47uH
E2
1
C1
2.2uF
100V
+ CIN1
10uF
100V
VIN
18V - 72V
GND
VCC
C7
U1
LT3758AEMSE
9
SHDN/UVLO
VC
FBX
4
RT
GATE
2
SENSE
GND
6
1
2
3
7
4
SYNC
SS
11
R5
0.02
1W
Q1
FDMS2572
L1-2
47uH
C10
4.7uF
10V
5
6
7
8
INTVcc
8
VIN
1
2
R6
30.9K
4
R7
42.2K
C13
5
3
0.1uF
10
4.7uF
100V
E5
1
schematic Diagram
ON
JP1
RUN
2
OFF
3
C12
100pF
C11
4.7nF
E3
+ C3
22uF
35V
+ C4
22uF
35V
C5
3.3uF
25V
VOUT
24V @ 1.0A
GND
E4
SYNC
E6
R8
10K
R1
280K
1%
R2
20.0K
1%
GND
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.
E7
CONTRACT NO.
DATE
2/28/13
2/28/13
TECHNOLOGY
TITLE
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
LT3758AEMSE
High Efficiency SEPIC Converter
SIZE CAGE CODE
APPROVED
APPROVALS
DRAWN
J. Wu
ENGINEER
W. Gu
CHECKED
DWG NO
DC1342B
Thursday, February 28, 2013
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DEMO MANUAL DC1342B
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