MCP1661 Isolated Flyback Converter Reference Design

MCP1661
Isolated Flyback Converter
Reference Design
 2014 Microchip Technology Inc.
DS50002313A
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
FlashFlex, flexPWR, JukeBlox, KEELOQ, KEELOQ logo, Kleer,
LANCheck, MediaLB, MOST, MOST logo, MPLAB,
OptoLyzer, PIC, PICSTART, PIC32 logo, RightTouch, SpyNIC,
SST, SST Logo, SuperFlash and UNI/O are registered
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
The Embedded Control Solutions Company and mTouch are
registered trademarks of Microchip Technology Incorporated
in the U.S.A.
Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo,
CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit
Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet,
KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo,
MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code
Generation, PICDEM, PICDEM.net, PICkit, PICtail,
RightTouch logo, REAL ICE, SQI, Serial Quad I/O, Total
Endurance, TSHARC, USBCheck, VariSense, ViewSpan,
WiperLock, Wireless DNA, and ZENA are trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
Silicon Storage Technology is a registered trademark of
Microchip Technology Inc. in other countries.
GestIC is a registered trademarks of Microchip Technology
Germany II GmbH & Co. KG, a subsidiary of Microchip
Technology Inc., in other countries.
All other trademarks mentioned herein are property of their
respective companies.
© 2014, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
ISBN: 978-1-63276-808-7
QUALITY MANAGEMENT SYSTEM
CERTIFIED BY DNV
== ISO/TS 16949 ==
DS50002313A-page 2
Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
 2014 Microchip Technology Inc.
Object of Declaration: MCP1661 Isolated Flyback Converter Reference Design
 2014 Microchip Technology Inc.
DS50002313A-page 3
MCP1661 Isolated Flyback Converter Reference Design
NOTES:
DS50002313A-page 4
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Table of Contents
Preface ........................................................................................................................... 7
Introduction............................................................................................................ 7
Document Layout .................................................................................................. 7
Conventions Used in this Guide ............................................................................ 8
Recommended Reading........................................................................................ 9
The Microchip Web Site ........................................................................................ 9
Customer Support ................................................................................................. 9
Document Revision History ................................................................................... 9
Chapter 1. Product Overview
1.1 Introduction ................................................................................................... 11
1.2 MCP1661 Device Short Overview ................................................................ 11
1.2.1 MCP1661 Key Features ............................................................................ 11
1.3 Flyback Converter Topology Overview ........................................................ 12
1.3.1 Flyback Converter Working Principle ........................................................ 13
1.4 What is The MCP1661 Isolated Flyback Converter Reference Design? ...... 13
1.5 What does The MCP1661 Isolated Flyback Converter Reference Design
Kit include? ............................................................................................. 13
Chapter 2. Installation and Operation
2.1 Introduction ................................................................................................... 15
2.1.1 Board Features .......................................................................................... 15
2.1.2 How Does the MCP1661 Isolated Flyback Converter Reference Design
Work? .................................................................................................... 16
2.2 Getting Started ............................................................................................. 17
2.2.1 Powering the MCP1661 Isolated Flyback Converter Reference Design ... 17
2.2.2 Board Testing ............................................................................................ 17
2.2.3 Results ...................................................................................................... 18
Appendix A. Schematic and Layouts
A.1 Introduction .................................................................................................. 21
A.2 Board – Schematic ....................................................................................... 22
A.3 Board – Top Silk .......................................................................................... 23
A.4 Board – Top Copper and Silk ....................................................................... 23
A.5 Board – Top Copper .................................................................................... 24
A.6 Board – Bottom Copper ............................................................................... 24
Appendix B. Bill of Materials
Worldwide Sales and Service .................................................................................... 26
 2014 Microchip Technology Inc.
DS50002313A-page 5
MCP1661 Isolated Flyback Converter Reference Design
NOTES:
DS50002313A-page 6
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Preface
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our web site
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the
document.
For the most up-to-date information on development tools, see the MPLAB® IDE on-line help.
Select the Help menu, and then Topics to open a list of available online help files.
INTRODUCTION
This chapter contains general information that will be useful to know before using the
MCP1661 Isolated Flyback Converter Reference Design. Items discussed in this
chapter include:
•
•
•
•
•
•
Document Layout
Conventions Used in this Guide
Recommended Reading
The Microchip Web Site
Customer Support
Document Revision History
DOCUMENT LAYOUT
This document describes how to use the MCP1661 Isolated Flyback Converter
Reference Design as a development tool. The manual layout is as follows:
• Chapter 1. “Product Overview” – Important information about the MCP1661
Isolated Flyback Converter Reference Design.
• Chapter 2. “Installation and Operation” – Includes instructions on how to
configure the board and important information about MCP1661 Isolated Flyback
Converter and a description of the Reference Design.
• Appendix A. “Schematic and Layouts”– Shows the schematic and layout
diagrams for MCP1661 Isolated Flyback Converter Reference Design.
• Appendix B. “Bill of Materials” – Lists the parts used to build the MCP1661
Isolated Flyback Converter Reference Design.
 2014 Microchip Technology Inc.
DS50002313A-page 7
MCP1661 Isolated Flyback Converter Reference Design
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description
Arial font:
Italic characters
Initial caps
Quotes
Underlined, italic text with
right angle bracket
Bold characters
N‘Rnnnn
Text in angle brackets < >
Courier New font:
Plain Courier New
Represents
Referenced books
Emphasized text
A window
A dialog
A menu selection
A field name in a window or
dialog
A menu path
MPLAB® IDE User’s Guide
...is the only compiler...
the Output window
the Settings dialog
select Enable Programmer
“Save project before build”
A dialog button
A tab
A number in verilog format,
where N is the total number of
digits, R is the radix and n is a
digit.
A key on the keyboard
Click OK
Click the Power tab
4‘b0010, 2‘hF1
Italic Courier New
Sample source code
Filenames
File paths
Keywords
Command-line options
Bit values
Constants
A variable argument
Square brackets [ ]
Optional arguments
Curly brackets and pipe
character: { | }
Ellipses...
Choice of mutually exclusive
arguments; an OR selection
Replaces repeated text
Represents code supplied by
user
DS50002313A-page 8
Examples
File>Save
Press <Enter>, <F1>
#define START
autoexec.bat
c:\mcc18\h
_asm, _endasm, static
-Opa+, -Opa0, 1
0xFF, ‘A’
file.o, where file can be
any valid filename
mcc18 [options] file
[options]
errorlevel {0|1}
var_name [,
var_name...]
void main (void)
{ ...
}
 2014 Microchip Technology Inc.
Preface
RECOMMENDED READING
This user’s guide describes how to use MCP1661 Isolated Flyback Converter Reference Design. Other useful documents are listed below. The following Microchip documents are available and recommended as supplemental reference resources.
• MCP1661 – “High-Voltage Integrated Switch PWM Boost Regulator with
UVLO” (DS20005315)
• MCP1662 – “High-Voltage Step-Up LED Driver with UVLO and Open Load
Protection” (DS20005316)
THE MICROCHIP WEB SITE
Microchip provides online support via our web site at www.microchip.com. This web
site is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the web site contains the following
information:
• Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
• General Technical Support – Frequently Asked Questions (FAQs), technical
support requests, online discussion groups, Microchip consultant program
member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the web site at:
http://www.microchip.com/support
DOCUMENT REVISION HISTORY
Revision A (November 2014)
• Initial Release of this Document.
 2014 Microchip Technology Inc.
DS50002313A-page 9
MCP1661 Isolated Flyback Converter Reference Design
NOTES:
DS50002313A-page 10
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Chapter 1. Product Overview
1.1
INTRODUCTION
This chapter provides an overview of the MCP1661 Isolated Flyback Converter
Reference Design and covers the following topics:
•
•
•
•
1.2
MCP1661 Device Short Overview
Flyback Converter Topology Overview
What is The MCP1661 Isolated Flyback Converter Reference Design?
What does The MCP1661 Isolated Flyback Converter Reference Design Kit
include?
MCP1661 DEVICE SHORT OVERVIEW
MCP1661 is a constant Pulse-Width Modulation (PWM) frequency boost (step-up)
converter (see Figure 1-1), based on a Peak Current mode architecture which delivers
high efficiency over a wide load range from two-cell and three-cell Alkaline, Energizer®
Ultimate Lithium, NiMH, NiCd and single-cell Li-Ion battery inputs. A high level of
integration lowers total system cost, eases implementation and reduces board area.
1.2.1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
MCP1661 Key Features
36V, 800 mΩ Integrated Switch
Up to 92% Efficiency
High Output Voltage Range: up to 32V
1.3A Peak Input Current Limit:
- IOUT > 200 mA @ 5.0V VIN, 12V VOUT
- IOUT > 125 mA @ 3.3V VIN, 12V VOUT
- IOUT > 100 mA @ 4.2V VIN, 24V VOUT
Input Voltage Range: 2.4V to 5.5V
Undervoltage Lockout (UVLO):
- UVLO@VIN Rising: 2.3V, typical
- UVLO@VIN Falling: 1.85V, typical
No Load Input Current: 250 μA, typical
Sleep Mode with 200 nA Typical Quiescent Current
PWM Operation with Skip Mode: 500 kHz
Cycle-by-Cycle Current Limiting
Internal Compensation
Inrush Current Limiting and Internal Soft-Start
Output Overvoltage Protection (OVP) in the event of:
- Feedback pin shorted to GND
- Disconnected feedback divider
Overtemperature Protection
Easy Configurable for SEPIC or Flyback Topologies
Available Packages:
- 5-Lead SOT-23
- 2x3 8-Lead TDFN
 2014 Microchip Technology Inc.
DS50002313A-page 11
MCP1661 Isolated Flyback Converter Reference Design
D
PMEG2005
L
4.7 µH
CIN
4.7 – 10 µF
VIN
2.4V – 3.0V
SW
VIN
MCP1661
VFB
ALKALINE
+
EN
-
ALKALINE
+
VOUT
12V, 75 mA – 125 mA
RT
1.05 MΩ
COUT
4.7 – 10 µF
RB
120 kΩ
GND
ON
OFF
-
FIGURE 1-1:
1.3
Typical MCP1661 Boost Converter
FLYBACK CONVERTER TOPOLOGY OVERVIEW
The flyback converter is used in both AC/DC and DC/DC conversion having galvanic
isolation between the input and one or more outputs. This type of converter is a
derivation from a buck-boost converter with a transformer replacing the inductor, so
that the voltage ratios are multiplied.
Being an isolated power converter, the control circuit needs to be isolated as well.
There are two control types used for this converter: Voltage mode control and Current
mode control. Both require a signal related to the output voltage. This can be achieved
using an optocoupler on the secondary circuitry to send a signal to the controller, or
using a separate winding on the coil and rely on the cross regulation of the design.
The first approach involving an optocoupler is used to obtain very good voltage and
current regulation, whereas the second was developed for cost-sensitive applications
where the output does not need to be as precisely controlled, but simplifies the overall
design considerably. In applications where reliability is critical, optocouplers should be
avoided.
In this application, a simpler technique (explained in the following chapters), was used,
but the main disadvantage is that the voltage regulation is poor. To improve this, an
LDO was added at the isolated output, in order to provide smooth regulation.
DS50002313A-page 12
 2014 Microchip Technology Inc.
Product Overview
1.3.1
Flyback Converter Working Principle
The schematic of a flyback converter can be seen in Figure 2-1. It derives from the
buck-boost topology but uses a transformer instead of the inductor. A very important
aspect is that flyback transformers have an air gap which allows energy storing without
the risk of core saturation occurrence. Therefore, the operating principle of both
converters is very close:
• When the switch is closed (Figure 1-2, a), the primary winding of the transformer
is connected to the input voltage source. The primary current and magnetic flux in
the transformer increases, storing energy in the transformer’s core. The voltage
induced in the secondary winding is negative, so the diode is reverse-biased. In
this phase, the output capacitor supplies energy to the output load (LDO’s input, in
this application).
• When the switch is opened (Figure 1-2, b), the primary current and magnetic flux
drops. The secondary voltage is positive, forward-biasing the diode, allowing current to flow from the transformer to the capacitor and to the load.
+
-
+
-
(a)
FIGURE 1-2:
1.4
(b)
The Two Configurations of the Flyback Converter In Operation.
WHAT IS THE MCP1661 ISOLATED FLYBACK CONVERTER REFERENCE
DESIGN?
The MCP1661 Isolated Flyback Converter Reference Design is used to evaluate and
demonstrate Microchip Technology’s MCP1661 in the following topology:
• 5V output Isolated Flyback Converter application supplied from 5V typical input
voltage.
It is used to evaluate the 5-Lead SOT-23 package.
By changing the LDO, a lower/higher output voltage than 5V will be obtained, but with
different capabilities regarding maximum output current and efficiency.
1.5
WHAT DOES THE MCP1661 ISOLATED FLYBACK CONVERTER
REFERENCE DESIGN KIT INCLUDE?
This MCP1661 Isolated Flyback Converter Reference Design kit includes:
• MCP1661 Isolated Flyback Converter Reference Design (ARD00598)
• Important Information Sheet
 2014 Microchip Technology Inc.
DS50002313A-page 13
MCP1661 Isolated Flyback Converter Reference Design
NOTES:
DS50002313A-page 14
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Chapter 2. Installation and Operation
2.1
INTRODUCTION
MCP1661 device is a non-synchronous, fixed-frequency step-up DC-DC converter
which has been developed for applications that require higher output voltage
capabilities. MCP1661 can regulate the output voltage up to 32V and can deliver
125 mA typical load at 3.3V input and 12V output. At light loads, MCP1661 skips pulses
in order to keep the output voltage in regulation, but the voltage ripple is maintained
low. The regulated output voltage should be greater than the input voltage.
2.1.1
Board Features
The MCP1661 Flyback Converter has the following features:
• Input Voltage: 4.25V-5.25V, Typical
- USB standard input voltage range
• Output Capability:
- Over 200 mA (at VOUT = 5V)
- Galvanic isolation
- Short-circuit protection
• Efficiency: up to 75%
• PWM Operation at 500 kHz
1
TR1
3
D1
7
VOUTS
CINS
10 µF
9
VOUT
5V, 200 mA
VOUT
VIN
MCP1755
GND
D2
VIN
4.25V – 5.25V
VOUTP
SW
VIN
CIN
10 µF
MCP1661
VFB
EN
FIGURE 2-1:
COUTS
1 µF
RT
100 kΩ
COUT
1 µF
RL
5.6 kΩ
RB
10 kΩ
GND
MCP1661 Isolated Flyback Converter.
 2014 Microchip Technology Inc.
DS50002313A-page 15
MCP1661 Isolated Flyback Converter Reference Design
This application uses MCP1661 as an open-loop flyback converter, the primary winding
of the transformer being used as inductor for the boost converter that clamps the primary output voltage (VOUTP) at around 13.5V. It is very important (for a normal operation of the entire circuitry and to avoid damaging some electronic components) not to
connect any additional load between VOUTP and GND. The output voltage of the flyback converter (VOUTS) drops with the increasing of output current, due to the fact that
the feedback is taken from the primary side.
In order to achieve a very good output voltage regulation in the secondary side (VOUT),
a 5V LDO is placed after the rectifying diode of the flyback converter, therefore the
decrease of VOUTS when increasing the load is not critical.
The MCP1661 Isolated Flyback Converter Reference Design can be used for
USB-powered applications, where a positive, regulated 5V output voltage is needed
from an isolated input voltage that varies from 4.75V to 5.25V.
2.1.2
How Does the MCP1661 Isolated Flyback Converter Reference
Design Work?
The converter is configured as non-synchronous; an external diode (D2) is connected
between the inductor (primary winding of the transformer) and the high-voltage output
(VOUTP). The transformation ratio chosen was 1:1, because the difference between the
input voltage range (VIN) and the output voltage (VOUT) is small.
The output voltage of the flyback converter (VOUTS) decreases by increasing the load
current, due to the lack of feedback from the secondary side of the transformer. The
amount of voltage drop (VOUTS) on the entire range of loads can be controlled by
changing the load resistor RL. Charging the primary side of the flyback transformer with
a higher current corresponds to a lower voltage drop in the secondary side (VOUTS)
over the entire load range, but the overall efficiency of the converter will decrease.
There is a compromise between the maximum output current capabilities, input voltage
range and efficiency, by varying the values of the load resistor (RL) and feedback resistors (RT and RB). In this case, those components were chosen in order to achieve good
efficiency at 200 mA load current up to 5.25V input voltage.
The two sense resistors (RT and RB) set the output (VOUTP) at 13.5V according to the
following equation:
EQUATION 2-1:
FEEDBACK RESISTORS RELATIONSHIP
 V OUTP

RT = R B   -------------------- – 1 
V
 FB

Where:
VFB
=
1.227V
VFB
=
Reference voltage of the FB pin
VOUTP
=
13.5V
RB
=
Resistor’s value is selected by the designer
Attention should be paid to the values of the feedback resistors. When testing the board
for other output voltage, a potential issue with higher value resistors is the environmental contamination, which can create a leakage current path on the Printed Circuit Board
(PCB). This will affect the feedback voltage and the output voltage regulation.
Engineers should use with precaution resistors that are larger than 1 MΩ. In normal
humidity conditions, the VFB input leakage is very low and the resistors’ values will not
affect the stability of the system.
All compensation and protection circuitry is integrated to minimize the number of external components. Ceramic input and output capacitors are used.
Good efficiency is obtained at high load currents due to the decreasing of the output
voltage before the LDO (VOUTS).
DS50002313A-page 16
 2014 Microchip Technology Inc.
Installation and Operation
2.2
GETTING STARTED
The MCP1661 Flyback Converter Reference Design is fully assembled and tested to
evaluate and demonstrate the MCP1661 family of products.
2.2.1
Powering the MCP1661 Isolated Flyback Converter Reference
Design
Input power connectors are placed on the left side of the board:
• VIN for positive power
• GND for negative power
The maximum input voltage should not exceed 5.5V. This can cause damage to the
MCP1661.
The output connector is called VOUT, is referenced to SGND and is isolated from GND.
2.2.2
Board Testing
The variable power supply for testing requires output capability of at least 1A and a voltage range of 4.0V to 6V.
To test the board, follow these steps:
Set 5V
PWR Supply
FIGURE 2-2:
V-Meter
100Ω/1W
1. Connect the power supply at VIN and GND terminals of the board.
2. Set the power supply to 5.0V.
3. Connect a voltmeter and a 100Ω/1W resistor between VOUT and SGND connectors, as shown in Figure 2-2. Check to be sure the voltmeter indicates approximately 5V.
4. Set the power supply to 4.75V and verify with the voltmeter if the output of the
converter stays regulated (VOUT = 5V).
5. Set the power supply to 5.25V and verify with the voltmeter if the output of the
converter stays regulated (VOUT = 5V).
MCP1661 Isolated Flyback Converter Reference Design.
 2014 Microchip Technology Inc.
DS50002313A-page 17
MCP1661 Isolated Flyback Converter Reference Design
The board has several test points that help engineers analyze the switch node’s waveforms or MCP1661’s output:
• The test point of the MCP1661 device’s switch node (SW).
• VOUTP test point shows the MCP1661 boost’s output voltage (this output is regulated).
• VOUTS test point shows the MCP1661 flyback’s output voltage (this output is
unregulated and is referenced to SGND).
The regulated output voltage of the boost is about 13.5V and is referenced to GND.
2.2.3
Results
MCP1661 Isolated Flyback Converter uses an uncommon design, because the
feedback voltage is taken from the primary side, so the output voltage in the secondary
side (VOUTS) drops down as long as the load current increases (see Figure 2-3).
However, the overall efficiency is still high, even if the LDO wastes some energy in
order to keep the output voltage (VOUT) stable at 5V.
5.05
LDO's input, VOUTS (V)
VIN = 5V
8.0
VIN = 5.25V
7.0
5.01
6.0
4.99
5.0
4.97
4.0
4.95
0
FIGURE 2-3:
DS50002313A-page 18
5.03
VIN = 4.75V
Converter's output, VOUT (V)
9.0
20 40 60 80 100 120 140 160 180 200
Load Current, IOUT (mA)
VOUTS vs. IOUT & VOUT vs. IOUT Graphs.
 2014 Microchip Technology Inc.
Installation and Operation
Refer to Figure 2-4 for the efficiency that can be obtained for different input voltages.
100
VOUT = 5V
Efficiency (%)
90
80
70
60
50
40
VIN = 4.75V
VIN = 5V
30
VIN = 5.25V
20
0
FIGURE 2-4:
20
40
60
80
100 120 140 160 180 200
IOUT (mA)
Efficiency vs. IOUT Graph for Different Input Voltages.
Figures 2-5 and 2-6 show the Discontinuous (at no load, 5V VIN) and Continuous mode
waveforms (50 mA load at 5V input voltage).
Secondary Side Switching Voltage
VSEC
10V/div
VPRI
10V/div
Primary Side Switching Voltage
2 µs/div
FIGURE 2-5:
Switching Nodes (Primary Side and Secondary Side) in
Discontinuous Conduction Mode (No Load).
 2014 Microchip Technology Inc.
DS50002313A-page 19
MCP1661 Isolated Flyback Converter Reference Design
Secondary Side Switching Voltage
VSEC
10V/div
Primary Side Switching Voltage
VPRI
10V/div
2 µs/div
FIGURE 2-6:
Switching Nodes (Primary Side and Secondary Side) in
Continuous Conduction Mode (50 mA Load Current).
Figure 2-7 shows the start-up waveforms for MCP1661 Isolated Flyback Converter at
150 mA load current.
Input Current
IIN
100 mA/div
VOUT
2V/div
Output Voltage
VSW
10V/div
Switching Voltage in the Primary Side of the Transformer
400 µs/div
FIGURE 2-7:
Voltage).
DS50002313A-page 20
Start-up Waveforms (Input Current, Output Voltage and Switching
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Appendix A. Schematic and Layouts
A.1
INTRODUCTION
This appendix contains the following schematics and layouts for the MCP1661 Flyback
Converter Reference Design:
•
•
•
•
•
Board – Schematic
Board – Top Silk
Board – Top Copper and Silk
Board – Top Copper
Board – Bottom Copper
 2014 Microchip Technology Inc.
DS50002313A-page 21
BOARD – SCHEMATIC
J1
7
*
3*
4
1
MBR0530T1G
9
C)
CINS
C2
C3
5
750310799
SGND
J2
VOUT
SGND
COUTS
C1
J3
SGND
DB
1
J5
VOUTP
1
D2
1
J4
VIN
3
1uF
16V
0805
SGND
VIN = 5V
VOUT
V
1uF
25V
0805
10uF
25V
1210
*
VIN
VOUT = 5V
1
1TR1
MCP1755S/5V
U1
GND
1
DF
D1
1
VOUTS
2
 2014 Microchip Technology Inc.
A.2
GND
MBR0530T1G
RT
R1
C5
10uF
16V
1210
1
J7
GND
DS50002313A-page 22
GND
GND
FB
GND
5
VIN
SW
3
1uF
25V
0805
2
1
1
CIN
EN
COUT
C4
MCP1661
GND
J6
SW
RL
R2
.k
0805
1%
RB
R3
10k
0805
1%
GND
GND
GND
J8
Schematic and Layouts
4
U2
100k
0805
1%
Schematic and Layouts
A.3
BOARD – TOP SILK
A.4
BOARD – TOP COPPER AND SILK
 2014 Microchip Technology Inc.
DS50002313A-page 23
MCP1661 Isolated Flyback Converter Reference Design
A.5
BOARD – TOP COPPER
A.6
BOARD – BOTTOM COPPER
DS50002313A-page 24
 2014 Microchip Technology Inc.
MCP1661 ISOLATED FLYBACK
CONVERTER REFERENCE DESIGN
Appendix B. Bill of Materials
TABLE B-1:
Qty.
BILL OF MATERIALS (BOM)
Reference
Description
Manufacturer
Part Number
1
C1
CAP. CER 1 µF 16V X7R 0805
TDK Corporation
C2012X7R1C105K125AA
1
C2
CAP. CER 10 µF 25V X7R 1210
TDK Corporation
C3225X7R1E106K250AC
2
C3, C4
CAP. CER 1 µF 25V X7R 0805
TDK Corporation
C2012X7R1E105K125AB
1
C5
CAP. CER 10 µF 16V X7R 1210
TDK Corporation
C3225X7R1C106K200AB
®
MBR0540T1G
2
D1, D2
SCHOTTKY RECT. 40V 0.5A
SOD123
ON Semiconductor
5
J2, J3, J4, J7,
J8
PC TEST POINT TIN SMD
HARWIN Plc.
1
PCB
MCP1661 Flyback Reference Design Microchip Technology Inc. 104-10321
– Printed Circuit Board
1
R1
RES. 100 kΩ 1/8W 1% 0805 SMD
Vishay Draloric
CRCW0805100KFKEA
S1751-46R
1
R2
RES. 5.6 kΩ, 1/8W 1% 0805 SMD
Vishay Draloric
CRCW08055K60FKEA
1
R3
RES. 10 kΩ 1/8W 1% 0805 SMD
Vishay Draloric
CRCW080510K0FKEA
1
TR1
Flyback Transformer, 25 µH, 15V, 1:1 WURTH Elektronik
1
U1
MCP1755S LDO 5V Output
Microchip Technology Inc. MCP1755S-5002E/DB
1
U2
MCP1661 High Voltage Boost
Switcher, 500 kHz
Microchip Technology Inc. MCP1661T-E/OT
0
J1, J5, J6
DO NOT POPULATE, Header, 2.54
mm, Vertical, THT
Samtec, Inc.
Note 1:
750310799
TSW-101-05-T-S
The components listed in this Bill of Materials are representative of the PCB assembly. The
released BOM used in manufacturing uses all RoHS-compliant components.
 2014 Microchip Technology Inc.
DS50002313A-page 25
Worldwide Sales and Service
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://www.microchip.com/
support
Web Address:
www.microchip.com
Asia Pacific Office
Suites 3707-14, 37th Floor
Tower 6, The Gateway
Harbour City, Kowloon
Hong Kong
Tel: 852-2943-5100
Fax: 852-2401-3431
India - Bangalore
Tel: 91-80-3090-4444
Fax: 91-80-3090-4123
Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
Denmark - Copenhagen
Tel: 45-4450-2828
Fax: 45-4485-2829
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
Atlanta
Duluth, GA
Tel: 678-957-9614
Fax: 678-957-1455
China - Beijing
Tel: 86-10-8569-7000
Fax: 86-10-8528-2104
Austin, TX
Tel: 512-257-3370
China - Chengdu
Tel: 86-28-8665-5511
Fax: 86-28-8665-7889
Boston
Westborough, MA
Tel: 774-760-0087
Fax: 774-760-0088
Chicago
Itasca, IL
Tel: 630-285-0071
Fax: 630-285-0075
Cleveland
Independence, OH
Tel: 216-447-0464
Fax: 216-447-0643
Dallas
Addison, TX
Tel: 972-818-7423
Fax: 972-818-2924
Detroit
Novi, MI
Tel: 248-848-4000
Houston, TX
Tel: 281-894-5983
Indianapolis
Noblesville, IN
Tel: 317-773-8323
Fax: 317-773-5453
Los Angeles
Mission Viejo, CA
Tel: 949-462-9523
Fax: 949-462-9608
New York, NY
Tel: 631-435-6000
San Jose, CA
Tel: 408-735-9110
Canada - Toronto
Tel: 905-673-0699
Fax: 905-673-6509
DS50002313A-page 26
China - Chongqing
Tel: 86-23-8980-9588
Fax: 86-23-8980-9500
China - Hangzhou
Tel: 86-571-8792-8115
Fax: 86-571-8792-8116
China - Hong Kong SAR
Tel: 852-2943-5100
Fax: 852-2401-3431
China - Nanjing
Tel: 86-25-8473-2460
Fax: 86-25-8473-2470
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
China - Shenzhen
Tel: 86-755-8864-2200
Fax: 86-755-8203-1760
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
India - New Delhi
Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
India - Pune
Tel: 91-20-3019-1500
Japan - Osaka
Tel: 81-6-6152-7160
Fax: 81-6-6152-9310
Japan - Tokyo
Tel: 81-3-6880- 3770
Fax: 81-3-6880-3771
Korea - Daegu
Tel: 82-53-744-4301
Fax: 82-53-744-4302
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
France - Paris
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
Germany - Dusseldorf
Tel: 49-2129-3766400
Germany - Munich
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
Germany - Pforzheim
Tel: 49-7231-424750
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Italy - Venice
Tel: 39-049-7625286
Malaysia - Kuala Lumpur
Tel: 60-3-6201-9857
Fax: 60-3-6201-9859
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
Poland - Warsaw
Tel: 48-22-3325737
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
Taiwan - Hsin Chu
Tel: 886-3-5778-366
Fax: 886-3-5770-955
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
Sweden - Stockholm
Tel: 46-8-5090-4654
UK - Wokingham
Tel: 44-118-921-5800
Fax: 44-118-921-5820
Taiwan - Kaohsiung
Tel: 886-7-213-7830
Taiwan - Taipei
Tel: 886-2-2508-8600
Fax: 886-2-2508-0102
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
03/25/14
 2014 Microchip Technology Inc.