Title
Reference Design Kit for a Low Standby
Current Non-Isolated Flyback Power Supply
Using LinkSwitch
TM
-TN2 LNK3202D
85 VAC – 277 VAC Input;
3.8 V / 20 mA and 12 V / 20 mA Outputs
Home and Building Automation
Applications Engineering Department
RDR-623
May 24, 2018
1.4
Specification
Application
Author
Document
Number
Date
Revision
Summary and Features
Highly integrated solution with LNK3202D
Low component count with integrated 725 V MOSFET, current sensing and protection
Wide range AC input
<65
A
standby input current across AC line
Two outputs, 3.8 V (±5%) and 12 V (±10%)
<7 mW no-load input power at 115 VAC
<12 mW no-load input power at 230 VAC
Load short-circuit protection
EN55022B conducted EMI compliant
PATENT INFORMATION
The products and applications illustrated herein (including transformer construction and circuits external to the products) 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
grants its customers a license under certain patent rights as set forth at <http://www.powerint.com/ip.htm>.
Power Integrations
5245 Hellyer Avenue, San Jose, CA 95138 USA.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.power.com
RDR-623 LinkSwitch-TN2 Low Standby Current Power Supply
24-May-18
1
2
3
4
Table of Contents
Introduction ............................................................................................................ 4
Power Supply Specification ...................................................................................... 5
Schematic ............................................................................................................... 6
Circuit Description ................................................................................................... 7
4.1
Input Rectifier, Protection and EMI Filtering ....................................................... 7
4.2
LinkSwitch-TN2 Primary Side and Main Output Circuit Operation ......................... 7
4.3
Regulation of Slave Output ................................................................................ 7
4.4
Output Side and Feedback Loop ........................................................................ 7
5 PCB Layout ............................................................................................................. 9
6 Bill of Materials ..................................................................................................... 10
7
Transformer Specification ...................................................................................... 11
7.1
Electrical Diagram ........................................................................................... 11
7.2
Electrical Specifications ................................................................................... 11
7.3
Material List ................................................................................................... 11
7.4
Transformer Build Diagram ............................................................................. 12
7.5
Transformer Instructions ................................................................................. 12
7.6
Transformer Winding Illustrations .................................................................... 13
8 Transformer Design Spreadsheet ........................................................................... 17
9 Performance Data ................................................................................................. 20
9.1
Full Load Efficiency vs. Input Line Voltage ........................................................ 20
9.1.1
Efficiency vs. Line Voltage, 0.3 W (20 mA on 12 V, 20 mA on 3.8 V) ........... 20
9.2
No-Load Input Power ...................................................................................... 21
9.3
Various Load Current vs. Input Line Voltage ..................................................... 22
9.4
Input Current at Standby vs. Input Line Voltage ............................................... 23
9.5
Line and Load Regulation ................................................................................ 24
9.5.1
12 V Line Regulation at 0.3 W (20 mA on 12 V, 20 mA on 5 V) ................... 24
9.5.2
3.8 V Line Regulation at 0.3 W (20 mA on 12 V, 20 mA on 3.8 V) ............... 25
9.5.3
3.8 V Regulation with Varying Load (12 V Unloaded) .................................. 26
10 Thermal Performance ............................................................................................ 27
10.1 Open Case ..................................................................................................... 27
10.2 85 VAC at Room Temperature ......................................................................... 27
10.3 265 VAC at Room Temperature ....................................................................... 29
11 Waveforms ........................................................................................................... 31
11.1
3.8 V Output Load Transient Response ............................................................ 31
11.2 12 V Output Load Transient Response ............................................................. 31
11.3 Switching Waveforms...................................................................................... 32
11.3.1 Drain to Source Voltage and Current during Normal Operation .................... 32
11.3.2 Drain to Source Voltage and Current Waveforms during Start-up ................ 33
11.3.3 Input and Output Voltages Waveforms during Start-up .............................. 34
11.3.4 Output Short Auto-Restart ........................................................................ 36
11.4 Output Ripple Measurements........................................................................... 37
11.4.1 Ripple Measurement Technique ................................................................ 37
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.power.com
Page
2 of 47
24-May-18
RDR-623 LinkSwitch-TN2 Low Standby Current Power Supply
11.4.2 Measurement Results ............................................................................... 38
12 Conducted EMI...................................................................................................... 40
12.1 Test Set-up Equipment ................................................................................... 40
12.1.1 Equipment and Load Used ........................................................................ 40
12.2 Floating Output (QP / AV) ............................................................................... 41
12.2.1 Line 115 VAC (0.3 W, 12 V and 3.8 V Full Load) ........................................ 41
12.2.2 Line 230 VAC (0.3 W, 12 V and 3.8 V Full Load) ........................................ 42
13 Lightning Surge Test ............................................................................................. 43
13.1 Differential Mode Surge Test ........................................................................... 43
13.2 Ring Wave Surge Test..................................................................................... 44
14 Revision History .................................................................................................... 46
Important Note:
Although this board is designed to satisfy safety isolation requirements, the engineering
prototype has not been agency approved. Therefore, all testing should be performed
using an isolation transformer to provide the AC input to the prototype board.
Page
3 of 47
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.power.com
RDR-623 LinkSwitch-TN2 Low Standby Current Power Supply
24-May-18
1
Introduction
This document is an engineering report describing a dual output 12 V, 20 mA and 3.8 V,
20 mA non-isolated power supply utilizing a device from the LinkSwitch-TN2 family of
ICs. This design shows the simplicity and efficiency that is possible due to the high level
of integration while still providing exceptional performance.
This document contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit layout, and performance data.
Figure 1 –
Populated Circuit Board Photograph, Top.
Figure 2 –
Populated Circuit Board Photograph, Bottom.
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.power.com
Page
4 of 47
24-May-18
RDR-623 LinkSwitch-TN2 Low Standby Current Power Supply
2
Power Supply Specification
The table below represents the minimum acceptable performance of the design. Actual
performance is listed in the results section.
Description
Input
Voltage
Frequency
No-load Input Power
Output
Output Voltage 1
Output Current 1
Output Voltage Ripple 1
Output Voltage 2
Output Current 2
Output Voltage Ripple 2
Peak Power Output
Environmental
Conducted EMI
Line Surge
Differential Mode
Ambient Temperature
T
AMB
0
500
24
V
o
Symbol
V
IN
f
LINE
V
OUT1
I
OUT1
V
RIPPLE1
V
OUT2
I
OUT2
V
RIPPLE2
P
OUT_PEAK
Min
85
47
Typ
115/230
50/60
Max
277
64
12
13.2
190
3.99
150
Units
VAC
Hz
mW
V
mA
mV
V
mA
mV
mW
Comment
2 Wire – No P.E.
230 VAC.
±10%.
20 MHz Bandwidth.
±5%
See Figure 14
20 MHz Bandwidth.
10.8
0
3.61
4
347
12
20
3.8
20
CISPR22B / EN55022B Floating
Resistive Load, 6 dB
Margin.
1.2
s
/ 50
s
Surge Mode,
2
Free Convection, Sea Level
in Sealed Enclosure.
C
Page
5 of 47
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
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