Title
Reference Design Report for a 6 W Non-
Dimmable, Non-Isolated Buck LED Driver
Using LYTSwitch
TM
-0 LYT0006P
Specification
90 VAC – 265 VAC Input; 54 V, 110 mA Output
Application
Author
Document
Number
Date
Revision
GU10 LED Driver Lamp Replacement
Applications Engineering Department
RDR-355
June 18, 2013
1.0
Summary and Features
Single-stage power factor corrected (>0.75 at 120 V and >0.5 at 230 V) and accurate constant current
(CC) output
Low cost, low component count and small PCB footprint solution
Highly energy efficient, >91 % at 120 VAC input
Highly energy efficient, >90 % at 240 VAC input
Superior performance and end user experience
Fast start-up time (<20 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
Meets IEC ring wave, differential line surge and EN55015 conducted EMI
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-355 6 W Non-Isolated Buck Using LYT0006P
18-Jun-13
Table of Contents
Introduction ................................................................................................................. 4
Power Supply Specification ........................................................................................ 6
Schematic ................................................................................................................... 7
Circuit Description ...................................................................................................... 8
4.1
Input EMI Filtering ............................................................................................... 8
4.2
LYTSwitch-0 ........................................................................................................ 8
4.3
Output Rectification ............................................................................................. 8
4.4
Output Feedback ................................................................................................. 8
4.5
No-Load Protection ............................................................................................. 9
5
PCB Layout .............................................................................................................. 10
6
Bill of Materials ......................................................................................................... 12
7
Inductor Specification ............................................................................................... 13
7.1
Electrical Diagram ............................................................................................. 13
7.2
Electrical Specifications ..................................................................................... 13
7.3
Materials ............................................................................................................ 13
7.4
Inductor Build Diagram ...................................................................................... 14
7.5
Transformer Construction .................................................................................. 14
8
Inductor Design Spreadsheet ................................................................................... 15
9
Performance Data .................................................................................................... 17
9.1
Active Mode Efficiency ...................................................................................... 18
9.2
Output Current Regulation................................................................................. 19
9.2.1
Input Line and Load Voltage to Output Current Regulation ........................ 19
10
Thermal Performance ........................................................................................... 20
10.1
Equipment Used ................................................................................................ 20
11
Thermal Result...................................................................................................... 21
11.1
Thermal Scan .................................................................................................... 22
12
Waveforms ............................................................................................................ 23
12.1
Drain Voltage Normal Operation ....................................................................... 23
12.2
Drain Current at Normal Operation .................................................................... 24
12.3
Drain Voltage and Current When Output Short ................................................. 26
12.4
Drain Voltage and Current Start-up Profile ........................................................ 26
12.5
Output Current Start-up Profile .......................................................................... 27
12.6
Input-Output Profile ........................................................................................... 28
12.7
Line Sag and Surge ........................................................................................... 29
12.8
Brown-out/ Brown-in .......................................................................................... 30
13
Line Surge............................................................................................................. 31
14
Conducted EMI ..................................................................................................... 33
15
Audible Noise ........................................................................................................ 35
16
Appendix ............................................................................................................... 36
17
Revision History .................................................................................................... 39
1
2
3
4
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 2 of 40
RDR-355 6 W Non-Isolated Buck Using LYT0006P
18-Jun-13
1 Introduction
This document describes a cost effective power supply utilizing the LYTSwitch
TM
-0 family
(LYT0006P) in a highly compact buck topology.
This power supply operates over an input voltage range of 90 VAC to 264 VAC. The DC
bus voltage is high enough to support a 54 V output when using a buck topology. In a
buck converter the output voltage must always be lower than the input voltage. The
output voltage is also limited by the maximum duty cycle of the LYTSwitch-0, which also
requires the input voltage to be larger than the output voltage.
Figure 1 –
Populated Circuit Board Photograph, Top.
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 4 of 40
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