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Design Example Report
Title Specification Application Author Document Number Date Revision 3W Non-Isolated Buck-Boost Converter using LNK305P Input: 108-265 VAC Output: -12 V / 250 mA Home Appliance Power Integrations Applications Department DER-49 April 20, 2005 1.0
Summary and Features * * * * * * * * * * * Non-Isolated Topology - no direct path from input to output Low cost off the shelf inductor - no custom transformer required 15 components including EMI filter Loop Fault Protection Short Circuit Protection Hysteretic Thermal Shutdown Output Referenced to Neutral Precise Output Voltage control Frequency Jitter Excellent Conducted EMI (>10dB margin across spectrum) Extremely low standby power consumption (<200mW!)
The products and applications illustrated herein (including circuits external to the products and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A complete list of Power Integrations' patents may be found at www.powerint.com.
Power Integrations 5245 Hellyer Avenue, San Jose, CA 95138 USA. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
Table Of Contents
Introduction ......................................................................................................................3 Power Supply Specification..............................................................................................4 Schematic ........................................................................................................................5 Circuit Description ............................................................................................................5 PCB Layout......................................................................................................................6 Bill Of Materials ................................................................................................................7 Performance Data ............................................................................................................8 7.1 Efficiency...................................................................................................................8 7.2 No-load Input Power .................................................................................................8 7.3 Regulation.................................................................................................................9 7.3.1 Load...................................................................................................................9 7.3.2 Line ....................................................................................................................9 8 Waveforms.....................................................................................................................10 8.1 Source Voltage and Current, Normal Operation .....................................................10 8.2 Output Voltage Start-up Profile ...............................................................................10 8.3 Load Transient Response (75% to 100% Load Step) .............................................11 8.4 Output Ripple Measurements .................................................................................12 8.4.1 Ripple Measurement Technique ......................................................................12 8.4.2 Measurement Results......................................................................................13 9 Conducted EMI ..............................................................................................................14 10 Revision History..........................................................................................................15 Important Note: Although this board is designed to satisfy safety requirements, the engineering prototype has not been agency approved. In addition, as the output is not electrically isolated from the input, all testing should be performed using an isolation transformer to provide the AC line input to the prototype board. Design Reports contain a power supply design specification, schematic, bill of materials, and transformer documentation. Performance data and typical operation characteristics are included. Typically only a single prototype has been built. 1 2 3 4 5 6 7
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 2 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
1 Introduction
This document is an engineering prototype report describing a non-isolated -12 V, 250mA power supply utilizing a LNK305P. The document contains the power supply specification, schematic, bill-of-materials, printed circuit layout, and performance data.
AC Line -12VDC @ 250mA
AC Neutral
GND Figure 1 -Populated Circuit Board Photograph.
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
2 Power Supply Specification
Description Input Voltage Frequency No-load Input Power (240 VAC) Output Output Voltage 1 Output Ripple Voltage 1 Output Current 1 Total Output Power Continuous Output Power Efficiency Ambient Temperature Symbol VIN fLINE Min 108 47 Typ Max 265 64 0.2 13.2 200 250 Units VAC Hz W V mV mA W % 50/85
o
Comment
2 Wire - No Protective Earth
50/60
VOUT VRIPPLE1 IOUT POUT TAMB
10.8 0
12
10% 20 MHz Bandwidth 3.5 mA pre-load fitted on board
3 50 -20
Measured at 85 VAC, 25 oC Free convection, sea level. For operation at >70 C substitute D1 for a diode with trr 35 ns
C
Table 1 - Specifications
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Page 4 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
3 Schematic
R3
12k 1%
U1 J1
1
R4
EN BP 2.05k 1%
+
C4
10uF/50V
D1 RF1
47/3W
+
LNK305P
1N4007
L1
D
D3
1
J3
LINE
2.2mH
C5
0.1uF
MUR160
-12V @ 250mA
10uF/400V
10uF/400V
1500uH
1N4005GP
J2
1
RF2
1
NEUTRAL
47/3W
* RF2 not used
Figure 2 -Schematic.
4 Circuit Description
The circuit shown in Figure 2 is a non-isolated buck-boost (inverting) topology. The input voltage range is 108 to 265VAC 50/60Hz and provides a regulated -12V at 250mA. The buck-boost topology is essentially the non-isolated version of the Flyback Converter, in that the transformer is replaced with a single low cost inductor (L2). RF1 is a fusible link resistor. The input AC is half-wave rectified and filtered by D1 and C1. C1, L1 and C2 form a pi-filter network to reduce common-mode emissions imposed to the input line, this in conjunction with the built-in frequency jitter of the LinkSwitch-TN (U1) ensure sufficient conducted EMI margins. U1, D2 and L2 form the buck-boost switching cell, which converts the rectified bulk positive DC voltage on C2 into a negative voltage on C3 (w/r/t Neutral/GND). D2 samples the output voltage onto C4 as a positive voltage with respect to the source of U1. The EN pin of U1 is internally set to 1.65V (w/r/t pins 1,2, 7 and 8) this in conjunction with resistors R3 and R4 form a simple voltage divider to precisely set the output voltage to the desired level. C5 is a bypass capacitor that serves as high frequency decoupling and energy storage. This capacitor provides power to the IC as well as controls the auto-restart mechanism in the LinkSwitch-TN. Resistor R2 serves to reduce peak charging effects on C3 which tend to increase the output voltage, its static power dissipation is limited to less than 30mW. Without this additional resistor the standby power consumption would be less than 100mW.
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+
108 - 265VAC 50/60Hz
S
C1
+
C2
L2
D2
C3
100uF/25V
R2
3.3k
J4
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
5 PCB Layout
Figure 3 - Printed Circuit Layout
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 6 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
6 Bill Of Materials
Item QTY Ref Des Value 1 2 3 4 5 6 7 8 9 10 11 12 13 14 2 1 1 1 1 1 1 1 1 1 1 1 1 1 C1, C2 C3 C4 C5 D1 D2 D3 L1 L2 R2 R3 R4 RF1 U1 10uF/400V 100uF/25V 10uF/50V 0.1uF/50V Standard Rec. 1A/1000V Standard Rec. 1A/600V Ultrafast 1A/600V 2.2mH 1500uH 3.3k 5% 1/4W 12k 1% 1/8W 2.05k 1% 1/8W 47 ohm/3W PWM +MOSFET Manufacturer P/N
Diodes, Inc. Diodes, Inc. Diodes, Inc. Toko Toko
1N4007 1N4005GP MUR160 262LY-222K 824MY-152K
RCD Components Power Integrations
LNK305P
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
7
7.1
Performance Data
Efficiency
80.00% 70.00% 60.00% Efficiency (%) 50.00% Vin = 108VAC 40.00% 30.00% 20.00% 10.00% 0.00% 0 50 100 150 200 250 300 Load Current (mA) Vin = 120VAC Vin = 240VAC Vin = 265VAC
All measurements performed at room temperature, 60 Hz input frequency.
Figure 4 - Efficiency vs. Output Current, Room Temperature, 60 Hz.
7.2
No-load Input Power
0.5 0.45 0.4 0.35 Input Power (W) 0.3 0.25 0.2 0.15 0.1 0.05 0 80 130 180 Input Voltage (VAC) 230 280
Figure 5 - Zero Load Input Power vs. Input Line Voltage, Room Temperature, 60 Hz.
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 8 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
7.3
Regulation
7.3.1 Load
13 12.8 12.6 Output Voltage (VDC) 12.4 12.2 12 11.8 11.6 11.4 11.2 11 0 50 100 150 Load Current (mA) 200 250 300
Figure 6 - Load Regulation, Vin = 120VAC, Room Temperature.
7.3.2 Line
13 12.8 12.6 Output Voltage (VDC) 12.4 12.2 12 11.8 11.6 11.4 11.2 11 80 130 180 Input Voltage (VAC) 230 280
Figure 7 - Line Regulation, Full Load, Room Temperature.
Page 9 of 17
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
8 Waveforms
8.1 Source Voltage and Current, Normal Operation
Figure 8 - 108 VAC, Full Load. Upper: IDRAIN, 0.2 A / div Lower: VSOURCE, 50 V, 5 s / div
Figure 9 - 265 VAC, Full Load. Upper: IDRAIN, 0.2 A / div Lower: VSOURCE, 100 V / div
8.2
Output Voltage Start-up Profile
Figure 10 - 108 VAC Input and Maximum Load. 5 V / div, 10 ms
Figure 11 - 265 VAC Input and Maximum Load. 5 V / div, 10 ms
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 10 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
8.3 Load Transient Response (75% to 100% Load Step) The oscilloscope was triggered using the load current step as a trigger source.
Figure 12 -120 VAC Input and Maximum Load. 50 mV / div, 5 ms / div
Page 11 of 17
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
8.4
Output Ripple Measurements
8.4.1 Ripple Measurement Technique For DC output ripple measurements, a modified oscilloscope test probe must be utilized in order to reduce spurious signals due to pickup. Details of the probe modification are provided in Figure 13 and Figure 14. The 5125BA probe adapter is affixed with two capacitors tied in parallel across the probe tip. The capacitors include one (1) 0.1 F/50 V ceramic type and one (1) 1.0 F/50 V aluminum electrolytic. The aluminum electrolytic type capacitor is polarized, so proper polarity across DC outputs must be maintained (see below).
Probe Ground
Probe Tip
Figure 13 - Oscilloscope Probe Prepared for Ripple Measurement. (End Cap and Ground Lead Removed).
Figure 14 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter (Modified with Wires for Probe Ground for Ripple Measurement and Two Parallel Decoupling Capacitors Added).
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 12 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
8.4.2 Measurement Results
Figure 15 - Ripple, 108 VAC, Full Load. 5 ms, 50 mV / div
Figure 16 - Ripple, 265 VAC, Full Load. 5 ms, 50 mV / div
Page 13 of 17
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
9 Conducted EMI
Figure 17- Conducted EMI EN55022 B Limits - 120 VAC/60Hz Maximum Steady State Load (LINE)
Note: If more EMI margin is desired, an additional 1N4007 can be added in series with the NEUTRAL input
.
Figure 18- Conducted EMI EN55022 B Limits - 120 VAC/60Hz Maximum Steady State Load (Neutral)
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 14 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
10 Revision History
Date April 20, 2005 Author RSP Revision 1.0 Description & changes Initial Release Reviewed VC/JC / AM
Page 15 of 17
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DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
NOTES
Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com
Page 16 of 17
DER-49
-12V/3W, Non-Isolated Buck-Boost Converter
April 20, 2005
For the latest updates, visit our Web site: www.powerint.com Power Integrations may make changes to its products at any time. Power Integrations has no liability arising from your use of any information, device or circuit described herein nor does it convey any license under its patent rights or the rights of others. POWER INTEGRATIONS MAKES NO WARRANTIES HEREIN AND SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS. PATENT INFORMATION The products and applications illustrated herein (including circuits external to the products and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A complete list of Power Integrations' patents may be found at www.powerint.com. The PI Logo, TOPSwitch, TinySwitch, LinkSwitch, and EcoSmart are registered trademarks of Power Integrations. PI Expert and DPA-Switch are trademarks of Power Integrations. (c) Copyright 2004, Power Integrations.
Power Integrations Worldwide Sales Support Locations
WORLD HEADQUARTERS 5245 Hellyer Avenue, San Jose, CA 95138, USA Main: +1-408-414-9200 Customer Service: Phone: +1-408-414-9665 Fax: +1-408-414-9765 e-mail: usasales@powerint.com CHINA (SHANGHAI) Rm 807, Pacheer, Commercial Centre, 555 Nanjing West Road, Shanghai, 200041, China Phone: +86-21-6215-5548 Fax: +86-21-6215-2468 e-mail: chinasales@powerint.com CHINA (SHENZHEN) Rm# 1705, Bao Hua Bldg. 1016 Hua Qiang Bei Lu, Shenzhen, Guangdong, 518031, China Phone: +86-755-8367-5143 Fax: +86-755-8377-9610 e-mail: chinasales@powerint.com APPLICATIONS HOTLINE World Wide +1-408-414-9660 GERMANY Rueckertstrasse 3, D-80336, Munich, Germany Phone: +49-895-527-3910 Fax: +49-895-527-3920 e-mail: eurosales@powerint.com JAPAN Keihin-Tatemono 1st Bldg. 12-20 Shin-Yokohama, 2-Chome, Kohoku-ku, Yokohama-shi, Kanagawa 222-0033, Japan Phone: +81-45-471-1021 Fax: +81-45-471-3717 e-mail: japansales@powerint.com KOREA 8th Floor, DongSung Bldg. 17-8 Yoido-dong, Youngdeungpo-gu, Seoul, 150-874, Korea Phone: +82-2-782-2840 Fax: +82-2-782-4427 e-mail: koreasales@powerint.com SINGAPORE 51 Newton Road, #15-08/10 Goldhill Plaza, Singapore, 308900 Phone: +65-6358-2160 Fax: +65-6358-2015 e-mail: singaporesales@powerint.co m TAIWAN 17F-3, No. 510, Chung Hsiao E. Rd., Sec. 5, Taipei, Taiwan 110, R.O.C. Phone: +886-2-2727-1221 Fax: +886-2-2727-1223 e-mail: taiwansales@powerint.com
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ER or EPR template - Rev 3.6 - Single sided
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