Title
Reference Design Report for 4.5 W Power
Factor Corrected LED Driver (Non-Isolated
Buck Boost) Using LinkSwitch
TM
-PL
LNK458KG
85 VAC – 135 VAC Input; 35 V, 130 mA Output
LED Driver for E17 Lamp Replacement
Applications Engineering Department
RDR-271
June 8, 2011
1.0
Specification
Application
Author
Document
Number
Date
Revision
Summary and Features
Single-stage power factor corrected and accurate constant current (CC) output
Low cost, low component count and small PCB footprint solution
Highly energy efficient, >85 % at 115 VAC input
Superior performance and end user experience
Fast start-up time (<300 ms) – no perceptible delay
Integrated protection and reliability features
Single shot no-load protection / output short-circuit protected with auto-recovery
Auto-recovering thermal shutdown with large hysteresis protects both components and PCB
No damage during brown-out conditions
PF >0.95 at 115 VAC
Meets EN55015 conducted EMI
%A THD <15% at 115 VAC
Meets IEC ring wave, differential line surge and EN55015 conducted EMI
No potting required up to 90 ºC internal ambient
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.powerint.com
RDR-271 4.5 W Buck Boost Power Supply Using LNK458KG
08-Jun-11
Table of Contents
Introduction ................................................................................................................. 4
Power Supply Specification ........................................................................................ 7
Schematic ................................................................................................................... 8
Circuit Description ...................................................................................................... 9
4.1
Input EMI Filtering ............................................................................................... 9
4.2
Buck Boost using LinkSwitch-PL ......................................................................... 9
4.3
Output Feedback ............................................................................................... 10
4.4
Disconnected Load Protection........................................................................... 10
4.5
Reference Design Kit ........................................................................................ 10
5
PCB Layout .............................................................................................................. 12
6
Bill of Materials ......................................................................................................... 15
6.1
Lamp Bill of Materials ........................................................................................ 15
6.2
LED Load Bill of Materials ................................................................................. 15
7
Inductor Specification ............................................................................................... 16
7.1
Electrical Diagram ............................................................................................. 16
7.2
Electrical Specifications ..................................................................................... 16
7.3
Materials ............................................................................................................ 16
7.4
Inductor Build Diagram ...................................................................................... 17
7.5
Inductor Construction ........................................................................................ 17
8
Inductor Illustration ................................................................................................... 18
9
Inductor Design Spreadsheet ................................................................................... 21
10
Performance Data ................................................................................................. 23
10.1
Active Mode Efficiency ...................................................................................... 23
10.2
Line Regulation ................................................................................................. 24
10.3
Power Factor ..................................................................................................... 25
10.4
%THD ................................................................................................................ 26
10.5
Harmonic Measurements .................................................................................. 27
11
Thermal Performance ........................................................................................... 29
11.1
Equipment Used ................................................................................................ 29
11.2
Thermal Results ................................................................................................ 30
12
Thermal Scans ...................................................................................................... 31
13
Waveforms ............................................................................................................ 32
13.1
Drain Voltage and Current, Normal Operation................................................... 32
13.2
Drain Voltage and Current Start-up Profile ........................................................ 33
13.3
Output Voltage Start-up Profile.......................................................................... 35
13.4
Drain Voltage and Current Start-up Short Profile .............................................. 36
13.5
Line Transient Response................................................................................... 37
13.6
Brown-out .......................................................................................................... 39
13.7
Start-up No-load ................................................................................................ 40
13.8
Line Surge Waveform ........................................................................................ 41
14
Line Surge............................................................................................................. 42
15
Conducted EMI ..................................................................................................... 43
15.1
Equipment: ........................................................................................................ 43
15.2
EMI Test Set-up ................................................................................................ 43
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
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Page 2 of 47
RDR-271 4.5 W Buck Boost Power Supply Using LNK458KG
08-Jun-11
1 Introduction
This document is an engineering report describing a non-isolated LED driver (power
supply) utilizing a LNK458KG from the LinkSwitch-PL family of devices.
The RD-271 provides a single constant current output of 130 mA over an LED string
voltage of 35 V.
The board was optimized to operate over the low AC input voltage range (85 VAC to 135
VAC, 47 Hz to 63 Hz). LinkSwitch-PL based designs provide a high power factor (>0.9)
meeting current international requirements.
The form factor of the board was chosen to meet the requirements for standard pear
shaped (E17) LED replacement lamps. The output is non-isolated and requires the
mechanical design of the enclosure to isolate the output of the supply and the LED load
from the user.
The document contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit layout, and performance data.
Figure 1 –
Size of Populated Circuit Board Photograph.
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 4 of 47
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