DC1643A - Demo Manual

DEMO MANUAL DC1643A
LT3575
Isolated Monolithic
Flyback Converter
Description
Demonstration circuit 1643A is an isolated flyback converter featuring LT®3575, a monolithic switching regulator
specifically designed for the isolated flyback converter with
an integrated 2.5A, 60V NPN transistor. The DC1643A is
designed for 5V output from a 10V to 28V DC input.
The output current capability depends on the input voltage, proper cooling, and the switch voltage stress. The
output current is up to 1.4A when the input is higher than
10V, and 2A when the input is higher than 20V but less
than 28V. The output current should not be higher than
2.4A for safe operation.
The IC requires minimum load to maintain good output
voltage regulation. A Zener diode D4 across the output
clamps the voltage to ~5.4V. The light load regulation can
be improved if a preload resistor (R4, optional) is installed.
Depending on input voltage and output regulation, a 40mA
minimum load is usually sufficient.
The DC1643A can be easily modified to generate different
output voltages. Some pre-designed transformers from
vendors such as Würth Electronics, Sumida, Pulse Engineering and Coilcraft, can be used for various applications.
The LT3575 operates with input supply voltages from
3V to 40V. The part senses the isolated output voltage
directly from the primary side flyback waveform. No
third winding or opto-coupler is required for regulation.
The LT3575 utilizes boundary mode operation to provide
a high efficiency, small size solution with improved load
regulation. It can be used in industrial, automotive and
medical applications where an isolated output is required.
The LT3575 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 DC1643A.
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
(TA = 25°C)
CONDITION
Input Voltage
MIN
TYP
10
4.75
MAX
28
5
5.25
UNITS
V
Output Voltage, VOUT
VIN = 10V to 28V, IOUT = 1.4A
Minimum Output Current
VIN = 20V
Maximum Output Current
VIN = 10V to 20V
VIN = 21V to 28V
Switching Frequency
VIN = 10V, IOUT = 1.4A
90
kHz
Efficiency
VIN = 28V, IOUT = 2A
86
%
40
V
mA
1.4
2
A
A
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DEMO MANUAL DC1643A
Quick Start Procedure
DC1643A is easy to set up to evaluate the performance
of the LT3575. Refer to Figure 1 for proper measurement
equipment setup and follow the procedure below:
ing frequency ripple can be reduced by increasing the
output capacitor C4, or adding a second stage LC filter.
Please contact factory for more information.
1.With power off, connect the input power supply to VIN
(E1) and GND (E2).
Note: The input EMI filter circuit (L1, FB1, C5, C19, and
C20) can be added by cutting the copper plane along the
notch next to C2 and C8 on the top layer of the demo
circuit.
2.Connect the load to the terminals VOUT+ (E5) and
VOUT – (E6) on the board. Apply 100mA load to VOUT+
and VOUT –.
3.Turn on the power at the input. Increase VIN to 10V
slowly.
Note: Make sure that the input voltage does not exceed
28V.
4. Check for the proper output voltages. The output should
be regulated at 5V (±5%).
Note: If there is no output, temporarily disconnect the
power supply. Make sure that the load is connected
with correct polarity. If the output voltage is out of
spec, make sure minimum load current is applied to
the output, the load is not set too high, and the input
current does not hit the power supply current limit.
Note: The compensation loop is designed with tradeoff between transient response and output ripple. To
reduce the low frequency output ripple, slow down the
loop by reducing R15 and increasing C11 (for instance,
change R15 to 6.4kΩ, and C11 to 22nF). The switch-
Note: For overload conditions, it is recommended to
operate the board at a reduced input voltage range
and/or reduce R8 of the RCD snubber. Please contact
the factory for more information.
5. Once the proper output voltage is established, adjust the
input and load within the operating range and observe
the output voltage regulation, ripple voltage, efficiency
and other parameters.
Note: When measuring the input or output voltage
ripples, 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 VIN and GND, or VOUT+ and VOUT – terminals. See
Figure 2 for proper scope probe technique. Typical efficiency and regulation curves are plotted in Figures 3
and 4, respectively.
6.Turn off the power supply. Disconnect the load from
the demo circuit.
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2
DEMO MANUAL DC1643A
quick start procedure
Figure 1. Proper Measurement Equipment Setup
INPUT OR OUTPUT CAPACITOR
100
5.8
90
5.6
80
5.4
70
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
60
50
40
30
5.2
5.0
4.8
4.6
4.4
20
10
0
0.1
VIN = 10V
VIN = 28V
0.6
1.6
1.1
LOAD CURRENT (A)
4.2
2
DC1643A F03
Figure 3. Typical Efficiency Curves
VIN = 10V
VIN = 28V
4.0
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9
LOAD CURRENT (A)
DC1643A F04
Figure 4. Typical Regulation Curves
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DEMO MANUAL DC1643A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
1
1
C1
Capacitor, 22µF 20% 50V Electrolytic
Sun Electronics 50CE22BS
2
1
C2
Capacitor, 1210 4.7µF 10% 50V X7R
Murata GRM32ER71H475KA88L
3
1
C4
Capacitor, 1210 47µF 10% 10V X7R
Murata GRM32ER71A476K
4
1
C7
Capacitor, 0603 0.1µF 10% 25V X5R
TDK C1608X5R1E104K
5
1
C8
Capacitor, 0603 100pF 5% 50V NPO
AVX 06035A101JAT2A
6
2
C9, C12
Capacitor, 0805 1µF 10% 50V X7R
Murata GRM21BR71H105KA12L
7
1
C10
Capacitor, 0805 0.22µF 10% 50V X7R
Taiyo Yuden UMK212B7224KG-T
8
1
C11
Capacitor, 0603 2200pF 10% 50V X7R
AVX 06035C222KAT2A
9
1
C13
Capacitor, 0603 10pF 5% 50V NPO
AVX 06035A100JAT2A
10
1
D1
Diode, Schottky, Barrier Rectifier 8A
Micro Semiconductor UPS840
11
1
D2
Diode, Schottky
Diode Inc. DFLS1100-7
12
1
D3
Diode, Schottky SOD323
Central Semiconductor CMDSH-3
13
1
D4
Diode, Power Zener 1.0W
Diodes/Zetex DFLZ5V6-7
14
1
R3
Resistor, 0603 357kΩ 1% 1/10W
NIC NRC06F3573TRF
15
1
R6
Resistor, 0603 93.1kΩ 1% 1/10W
Vishay CRCW060393K1FKED
16
1
R7
Resistor, 0603 80.6kΩ 1% 1/10W
Vishay, CRCW060380K6FKEA
17
1
R8
Resistor, 0805 2kΩ 1% 1/8W
Vishay CRCW08052K00FKEA
18
1
R9
Resistor, 0603 28.7kΩ 1% 1/10W
NIC NRC06F2872TRF
19
1
R10
Resistor, 0603 10kΩ 1% 1/10W
Vishay CRCW060310K0FKED
20
1
R11
Resistor, 0603 6.04kΩ 1% 1/10W
NIC NRC06F6041TRF
21
1
R15
Resistor, 0603 24.9kΩ 1% 1/10W
NIC NRC06F2492TRF
22
1
T1
Transformer
Würth 750311675
23
1
U1
IC, Monolithic Flyback Converter
Linear Technology LT3575EFE
Hardware – For Demo Board Only
1
5
Turret
Mill-Max 2501-2-00-80-00-00-07-0
2
1
E1, E2, E3, E5, E6
Fab, Printed Circuit Board
DC1643A
3
1
Stencil
Stencil
Capacitor, 22µF 20% 50V Electrolytic Optional
Sun Electronics 50CE22BS Optional
Additional Demo Board Circuit Components
1
0
C5
2
0
C14
Capacitor, 1206 0.033µF Optional
Optional
3
0
C19
Capacitor, 1210 4.7µF 10% 50V X7R Optional
Murata GRM32ER71H475K Option
4
0
C20
Capacitor, 0603 0.01µF 10% 50V X7R Optional
NIC NMC0603X7R104K50TRPF Optional
5
0
FB1
Ferrite Bead Optional
Taiyo Yuden FB MJ3216HS800 Optional
6
0
L1
Inductor, 10µH Optional
Sumida CDRH4D22/HP Optional
7
0
Q1
XSTR, MOSFET, N-Channel 30V Optional
Vishay Si3456DDV Optional
8
0
R4
Resistor, 0805 440Ω 1% 1/8W Optional
NIC NRC10F4400TRF
dc1643af
4
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
E3
22uF
50V
+ C1
R10
10k
1%
C7
0.1uF
SUN ELECT.
50CE22BS
VIN
C8
100pF
C2
4.7uF
50V
1210
5
U1
LT3575EFE
VC
SS
RILIM
TC
SHDN/UVLO
1. ALL CAPACITOR AND RESISTOR CASE SIZES ARE 0603.
C11
2200pF
9
7
8
12
6
C12
1uF
50V
0805
R15
24.9k
1%
R3
357K
1%
R6
93.1k
1%
NOTES: UNLESS OTHERWISE SPECIFIED,
R9
28.7k
1%
SHDN
GND
E2
10V - 28V
VIN
E1
4
5
RREF
RFB
SW
SW
R11
6.04k
1%
R7
80.6k
1%
C13
10pF
D2
DFLS1100
C10
0.22uF
50V
0805
2
R8
2k
1%
0805

4
3


C20
0.01uF
50V
1
2
D1
VIN

N/A

DFLZ5V6
5.6V
D4
C4
47uF
1210
10V
BEAD
C19
4.7uF
50V
1210
OPT
TECHNOLOGY
1206
C14
10uH
E6
22uF
50V
SUN ELECT.
50CE22BS
VOUT-
+ C5
VIN
R4
OPT
0805
E5
VOUT+
VOUT-
+5V @1.4A, VIN > 10V
+5V @2.0A, VIN > 20V
VOUT+
APPROVED
Zhongming Y.

2
1

DEMO CIRCUIT 1643A
LT3575EFE
ISOLATED MONOLITHIC FLYBACK
CONVERTER

2






SUMIDA
CDRH4D22/HP
L1
OPTIONAL CIRCUIT
TAIYO YUDEN
FB MJ3216HS800
FB1
UPS840
3
DATE
07/02/10
DESCRIPTION
PRODUCTION
1
2
REVISION HISTORY
REV
2
 
8
3
750311675
7
4
6
5
T1
ECO
2
1
 

 







11
10
4
3
C9
1uF
50V
0805
1
D3 CMDSH-3
3
1
2
D
1
NC
2
VIN
TEST
13
GND
14
NC
NC
15
16
BIAS
GND
17
1
2
5
A
B
C
D
DEMO MANUAL DC1643A
Schematic Diagram
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5
DEMO MANUAL DC1643A
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
dc1643af
6
Linear Technology Corporation
LT 1111 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2011
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