DER-388

Design Example Report
Title
9 W High Efficiency (90%) Power Factor
Corrected (>0.9) Non-Dimmable Non-Isolated
Buck A19 Lamp Replacement LED Driver
Using LinkSwitchTM-PL LNK457DG
Specification
195 VAC – 265 VAC Input;
60 V (Typical), 150 mA Output
Application
A19 LED Driver
Author
Applications Engineering Department
Document
Number
DER-388
Date
December 5, 2013
Revision
1.0
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, >90% at 220 VAC input
Fast start-up time (<50 ms) – no perceptible delay
Integrated protection and reliability features
 One shot no-load protection
 Hard short-circuit protected
 Auto-recovering thermal shutdown
 No damage during line brown-out or brown-in conditions
PF >0.9 at 230 VAC
ATHD <25% at 230 VAC
Meets IEC 2.5 kV ring wave, 500 V 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
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
Table of Contents
1 2 3 4 Introduction ................................................................................................................. 3 Power Supply Specifications ...................................................................................... 4 Schematic ................................................................................................................... 5 Circuit Description ...................................................................................................... 6 4.1 Input Stage .......................................................................................................... 6 4.2 Buck Topology Using LinkSwitch-PL Devices ..................................................... 6 4.3 Output Feedback ................................................................................................. 6 4.4 Disconnected Load Protection............................................................................. 6 4.5 Overload and Short-Circuit Protection ................................................................. 7 5 PCB Layout and Outline ............................................................................................. 8 6 Populated PCB ........................................................................................................... 9 7 Bill of Materials ......................................................................................................... 10 8 Transformer Design Spreadsheet............................................................................. 11 9 Performance Data .................................................................................................... 13 9.1 Efficiency ........................................................................................................... 13 9.2 Line Regulation ................................................................................................. 14 9.3 Power Factor ..................................................................................................... 15 9.4 %ATHD ............................................................................................................. 16 9.5 Harmonic Content ............................................................................................. 17 9.6 Harmonic Measurements .................................................................................. 18 9.7 Thermal Performance ........................................................................................ 19 9.8 Thermal Scans .................................................................................................. 19 10 Waveforms ............................................................................................................ 20 10.1 Drain Voltage and Current, Normal Operation................................................... 20 10.2 Drain Voltage and Current Start-up Profile ........................................................ 21 10.3 Output Voltage Start-up Profile.......................................................................... 22 10.4 Input and Output Voltage and Current Profiles .................................................. 23 10.5 Drain Voltage and Current Profile: Normal Operation to Output Short .............. 24 10.6 Drain Voltage and Current Profile: Start-up with Output Shorted ...................... 24 10.7 No-Load Operation ............................................................................................ 25 10.8 AC Cycling......................................................................................................... 26 10.9 Brown-out .......................................................................................................... 27 10.10 Line Surge ..................................................................................................... 28 11 Conducted EMI ..................................................................................................... 29 11.1 Equipment ......................................................................................................... 29 11.2 EMI Test Set-up ................................................................................................ 29 11.3 EMI Test Result ................................................................................................. 30 12 Revision History .................................................................................................... 32 Important Note:
Although this board is designed to satisfy safety requirements for non-isolated LED
drivers, 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.
Power Integrations, Inc.
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Page 2 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
1 Introduction
This document is an engineering report describing a non-isolated LED driver (power
supply) utilizing a LNK457DG from the LinkSwitch-PL family of devices.
The DER-388 provides a single 9 W constant current output.
The key design goals were high efficiency and small size. This allowed the driver to fit
into A19 sized lamps and be as close to a production design as possible.
Figure 1 – PCB Assembly.
The board was optimized to operate over the high-line AC input voltage range (195 VAC
to 265 VAC, 47 Hz to 63 Hz). LinkSwitch-PL IC 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 A19 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 board layout, PIXIs spreadsheet and
performance data.
Page 3 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
2 Power Supply Specifications
The table below represents the minimum acceptable performance of the design. Actual
performance is listed in the results section.
Description
Input
Voltage
Frequency
Output
Output Voltage
Output Current
Total Output Power
Continuous Output Power
Efficiency
Nominal
Symbol
Min
Typ
Max
Units
Comment
VIN
fLINE
195
47
230
50/60
265
63
VAC
Hz
2 Wire – no P.E.
VOUT
IOUT
54
60
150
66
V
mA
POUT
9
W

90
%
At 230 VAC
o
Measured at POUT 25 C at
220 VAC
Environmental
Conducted EMI
Meets CISPR22B / EN55015
Line Surge
Differential Mode (L1-L2)
500
V
1.2/50 s surge, IEC 1000-4-5,
Series Impedance:
Differential Mode: 2 
Ring Wave (100 kHz)
Differential Mode (L1-L2)
2.5
kV
2  Short-Circuit
Series Impedance
Power Factor
0.9
ATHD
At 230 VAC
25
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%
At 230 VAC
Page 4 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
3 Schematic
Figure 2 – Schematic for 60 V / 150 mA A19 Replacement Lamp.
Page 5 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
4 Circuit Description
The LinkSwitch-PL (U1) family is highly integrated power ICs intended for use in LED
driver applications. The LinkSwitch-PL provides high power factor in a single-stage
conversion topology while regulating the output current across the input range (195 VAC
to 265 VAC) and output voltage conditions typically encountered in LED driver
applications. All of the control circuitry required for these functions plus a high-voltage
power MOSFET is incorporated into the IC.
4.1 Input Stage
Fuse F1 provides protection against component failure. A relatively high, fast 5 A rating
was needed to prevent false opening during line surges. Fuse F1 may be replaced with a
fusible resistor (2 W, 3.3 ) for lower cost but could lower efficiency.
The maximum input voltage is clamped by RV1 during differential line surges.
The AC input is full wave rectified by BR1 for good power factor.
Capacitor C1, C2 and differential choke L1 form the EMI filter. Total input filter
capacitance is limited to low value to maintain high power factor. This input -filter
networks plus the frequency jittering feature of LinkSwitch-PL ensures compliance with
Class B emission limits. Resistor R1 damps the resonance of the EMI filter, preventing
peaks in the EMI spectrum when measured in a system (driver plus enclosure).
Inductor L1 is positioned after the bridge to avoid an imbalance in the EMI scan between
line and neutral. This also allows the use of small high-voltage ceramic capacitors in the
input filter.
4.2 Buck Topology Using LinkSwitch-PL Devices
The buck power train is composed of U1 (power switch + control), D1 (freewheeling
diode), C5 (output capacitor), and L2 (inductor). The bypass capacitor C8 provides the
internal supply for U1, it is charged via the drain during MOSFET off-time during start-up.
4.3 Output Feedback
The output current is sensed by the voltage drop across R2//R3 and then filtered by a low
pass filter (R5 and C6). This biases the LinkSwitch-PL operating point such that the
average FEEDBACK (FB) pin voltage is maintained at 290 mV in steady-state operation
(150 mA output current). Bypass capacitor C4 is used to reduce dissipation across
R2//R3 thus increasing efficiency.
4.4 Disconnected Load Protection
Simple one shot no-load protection is provided by a Zener (VR1) diode across the output
terminals. In case of no-load, the Zener diode will short in order to protect the output
capacitor from popping. U1 will be limited by the primary current limit. Note that the Zener
diode will need to be replaced once fault is removed.
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Page 6 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
4.5 Overload and Short-Circuit Protection
The load is protected against overload and short-circuits via a primary current limit.
During short, primary current will build-up until it reaches current limit. Refer to shortcircuit waveforms for more information.
Page 7 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
5 PCB Layout and Outline
Figure 3 – Printed Circuit Layout, Top.
Figure 4 – Printed Circuit Layout, Bottom.
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Page 8 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
6 Populated PCB
Figure 5 – Populated Circuit Board, Top.
Figure 6 – Populated Circuit Board, Bottom.
Page 9 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
7 Bill of Materials
Item
Qty
Ref Des
1
1
BR1
Description
600 V, 0.5 A, Bridge Rectifier, SMD, MBS-1, 4-SOIC
Mfg Part Number
Manufacturer
MB6S-TP
Micro Commercial
2
1
C1
47 nF, 630 V, Film
MEXPD24704JJ
Duratech
3
1
C2
220 nF, 450 V, Film
MEXXF32204JJ
Duratech
4
1
C3
10 F, 10 V, Ceramic, X7R, 0805
C2012X7R1A106M
TDK
5
1
C4
22 F, 16 V, Ceramic, X7R, 0805
C2012X5R1C226K
TDK
6
1
C5
68 F, 100 V, Electrolytic, (10 x 16)
UHE2A680MPD
Nichicon
7
1
C6
2.2 F, 10 V, Ceramic, X7R, 0805
8
1
D1
600 V, 1 A, Ultrafast Recovery, DO-41
9
1
F1
5 A, 250 V, Fast, Microfuse, Axial
10
1
L1
4.7 mH, 0.150 A, 20%
C0805C225M8RACTU
Kemet
STTH1R06RL
ST Micro
0263005.MXL
Littlefuse
RL-5480-3-4700
Renco Elect
11
1
L2
680 H
MSS1260-684KLB
Coilcraft
12
1
R1
4.7 k, 5%, 1/8 W, Thick Film, 0805
ERJ-6GEYJ472V
Panasonic
13
1
R2
3.00 , 1%, 1/4 W, Thick Film, 1206
RC1206FR-073RL
Yageo
14
1
R3
20 , 1%, 1/4 W, Metal Film
MFR-25FBF-20R0
Yageo
15
1
R5
3.3 k, 5%, 1/10 W, Thick Film, 0603
ERJ-3GEYJ332V
Panasonic
16
1
RV1
250 V, 21 J, 7 mm, RADIAL LA
V250LA4P
Littlefuse
17
1
U1
LinkSwitch-PL, SO-8C
LNK457DG
Power Integrations
18
1
VR1
91 V, 5%, 1 W, DO-41
1N4763A-TR
Vishay
Power Integrations, Inc.
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Page 10 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
8 Transformer Design Spreadsheet
ACDC_LinkSwitchPL-Buck_042413;
Rev.1.1; Copyright
INPUT
Power Integrations
2011
ENTER APPLICATION VARIABLES
VACMIN
195
VACTYP
230
VACMAX
254
FL
VOMIN
54.00
VO
60.00
VOMAX
66.00
IO
0.15
PO
n
Dimming Application
INFO
OUTPUT
UNIT
195.00
230.00
254.00
50.00
54.00
60.00
66.00
0.15
9.00
V
V
V
Hz
V
V
V
A
W
0.91
0.91
No
No
ENTER LinkSwitch-PL VARIABLES
Chosen Device
LNK457
ILIMITMIN
ILIMITTYP
ILIMITMAX
TON
FSW
Duty Cycle
IRMS
IPK
KDP
LNK457
0.80
0.91
1.02
2.02
121.33
24.46
0.12
0.75
Info
0.87
ENTER INDUCTOR CORE/CONSTRUCTION VARIABLES
Core Type
Core Type
Custom
Custom
Core Part Number
0.00
Bobbin part number
0.00
AE
0.00
LE
0.00
AL
0.00
BW
INDUCTOR DESIGN PARAMETERS
LPMIN
LPTYP
680.00
LP_TOLERANCE
TURNS_TOTAL
0.00
612.00
680.00
10.00
N/A
ALG
BM
BP
mm^2
mm
nH/tur
n^2
mm
N/A
N/A
uH
uH
%
Turns
nH/tur
n^2
Gauss
Gauss
N/A
N/A
N/A
A
A
A
us
kHz
%
A
A
BAC
N/A
N/A
Gauss
ur
LG
N/A
N/A
N/A
N/A
mm
Page 11 of 33
ACDC_LinkSwitch-PL Buck Design Spreadsheet
Minimum AC Input Voltage
Typical AC Input Voltage
Maximum AC Input Voltage
AC Mains Frequency. (between 47Hz and 63Hz)
Minimum Output Voltage of LED string
Output Voltage of LED string
Maximum Output Voltage of LED string
Output Current riving LED strings
Continuous Output Power
Efficiency Estimate at output terminals. Under 0.7 if no
better data available
Enter Yes if design uses TRIAC dimming, otherwise select
No
Chosen LinkSwitch-II device
Minimum Current Limit
Typical Current Limit
Maximum Current Limit
Expected on-time of MOSFET at low line and PO
Expected switching frequency at low line and PO
Expected operating duty cycle at low line and PO
Worst case drain RMS current at VO
Worst case peak primary current at VO
LinkSwitch-PL must operate in discontinuous mode (KP >
1) for good power factor. Consider reducing the primary
inductance.
Enter Transformer Core
If custom core is used - Enter part number here
Bobbin Part number (if available)
Core Effective Cross Sectional Area
Core Effective Path Length
Ungapped Core Effective Inductance
Bobbin Physical Winding Width
Minimum Inductance
Typical inductance
Tolerance of the inductance
Total number of turns
Gapped Core Effective Inductance
#DIV/0!
#DIV/0!
AC Flux Density for Core Loss Curves (0.5 X Peak to
Peak)
Relative Permeability of Ungapped Core
#DIV/0!
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DER-388 9 W Buck Power Supply Using LNK457DG
AWG
N/A
L
CMA
Bias Section
Use Bias?
No
TURNS_BIAS
VBIAS
PIVBS
CURRENT WAVEFORM SHAPE PARAMETERS
DMAX
N/A
N/A
N/A
Cmils
No
0.00
0.00
N/A
Turns
V
V
24.46
%
05-Dec-13
Winding Wire Gauge (Rounded to next smaller standard
AWG value)
Number of Layers
Current Density capacity 200 < CMA < 500
Is a Bias winding used?
Duty cycle measured at minimum input voltage
Input average current measured on the Mosfet at the
minimum input voltage
Peak Drain current at maximum input voltage
MOSFET RMS current measured at the minimum input
voltage
RMS current of freewheeling diode at maximum input
voltage
RMS current of the inductor at the maximum input voltage
IAVG
0.04
A
IP
0.75
A
ISW_RMS
0.12
A
ID_RMS
0.27
A
IL_RMS
FEEDBACK AND BYPASS PIN PARAMETERS
0.29
A
RFEEDBACK
2.72
ohm
CBP
VOLTAGE STRESS PARAMETERS
VDRAIN
PIVS
1.00
uF
This is a first approximation for the sense resistor and will
likely require fine tuning in the bench. Value calculated
with typical inductance, and minimum input voltage.
Minimum Bypass pin capacitor required
359.21
359.21
V
V
Estimated worst case drain voltage
Output Rectifier Maximum Peak Inverse Voltage
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Page 12 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
9 Performance Data
All measurements performed at 25 ºC room temperature otherwise specified.
9.1
Efficiency
92.0
54 V
60 V
66 V
91.5
Efficiency (%)
91.0
90.5
90.0
89.5
89.0
88.5
180
190
200
210
220
230
240
250
260
270
AC Input Voltage (VRMS / 50 Hz)
Figure 7 – Efficiency with Respect to AC Input Voltage.
Page 13 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
9.2 Line Regulation
The LinkSwitch-PL device regulates the output by controlling the power MOSFET on-time
and switching frequency to maintain the average FEEDBACK pin at its 0.29 V threshold.
Slight changes in output current may be observed when input or output conditions are
changed or after AC cycling due to the device selecting a slightly different operating state
(selection of on-time and frequency).
12.0
54 V
60 V
66 V
9.0
Regulaiton (%)
6.0
3.0
0.0
-3.0
-6.0
-9.0
-12.0
180
190
200
210
220
230
240
250
260
270
280
AC Input Voltage (VRMS / 50 Hz)
Figure 8 – Line Regulation, Room Temperature.
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Page 14 of 33
05-Dec-13
9.3
DER-388 9 W Buck Power Supply Using LNK457DG
Power Factor
0.98
54 V
60 V
66 V
0.96
Power Factor (PF)
0.94
0.92
0.90
0.88
0.86
0.84
0.82
180
190
200
210
220
230
240
250
260
270
AC Input Voltage (VRMS / 50 Hz)
Figure 9 – High Power Factor within the Operating Range.
Page 15 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
9.4
05-Dec-13
%ATHD
32
54 V
60 V
66 V
30
28
THD (%)
26
24
22
20
18
16
14
12
180
190
200
210
220
230
240
250
260
270
280
AC Input Voltage (VRMS / 50 Hz)
Figure 10 – Very Low %ATHD at 220 VAC.
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Page 16 of 33
05-Dec-13
9.5
DER-388 9 W Buck Power Supply Using LNK457DG
Harmonic Content
35
Limit
Measured
30
Current (mA)
25
20
15
10
5
0
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Harmonic Content
Figure 11 – Meets EN61000-3-2 Harmonics Contents Standards for <25 W Rating for 60 V LED Output.
Page 17 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
9.6
05-Dec-13
Harmonic Measurements
VAC
(VRMS)
230
nth
Order
1
2
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
Freq
(Hz)
50.00
mA
Content
46.37
0.04
5.58
4.23
3.27
1.99
1.79
1.37
1.79
1.52
1.33
1.08
1.06
0.88
0.86
0.69
0.73
0.38
0.32
0.55
0.24
0.36
0.35
0.21
0.28
0.29
I
(mA)
47.73
%
Content
0.09%
12.02%
9.11%
7.05%
4.30%
3.86%
2.95%
3.86%
3.28%
2.86%
2.34%
2.29%
1.89%
1.85%
1.49%
1.57%
0.82%
0.69%
1.18%
0.52%
0.77%
0.75%
0.45%
0.61%
0.63%
P
(W)
9.14
Limit (mA)
<25 W
34.5100
19.2850
10.1500
5.0750
3.5525
3.0060
2.6052
2.2987
2.0567
1.8608
1.6990
1.5631
1.4473
1.3475
1.2606
1.1842
1.1165
1.0561
1.0020
PF
0.925
Remarks
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Table 1 – 230 VAC Input Current Harmonic Measurement for 60 V LED.
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Page 18 of 33
05-Dec-13
9.7
DER-388 9 W Buck Power Supply Using LNK457DG
Thermal Performance
9.8 Thermal Scans
The scan is conducted at ambient temperature of 25 ºC open frame, 195 VAC / 50 Hz
input.
Figure 12 – SP1 – L2; Output Inductor.
SP2 – U1; LNK457DG Case Temperature.
SP3 – BR1; Bridge Case Temperature.
SP4 – Ambient Temperature.
Page 19 of 33
Figure 13 – SP1 – L1; Differential Choke Temperature.
SP2 – D1; Catch Diode Temperature.
SP3 – Ambient Temperature.
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
10 Waveforms
10.1 Drain Voltage and Current, Normal Operation
No saturation in the inductor and design guaranteed to work in discontinuous mode within
the operating input voltage.
Figure 14 – 195 VAC / 50 Hz, 60 V LED String.
Ch1: VBULK, 100 V / div.
Ch2: VS-G, 100 V / div.
Ch3: IDRAIN, 0.5 A / div.
F1: VD-S, 200 V / div.
Time Scale: 1 ms / div.
Zoom Time Scale: 10 s / div.
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Figure 15 – 240 VAC / 50 Hz, 60 V LED String.
Ch1: VBULK, 100 V / div.
Ch2: VS-G, 100 V / div.
Ch3: IDRAIN, 0.5 A / div.
F1: VD-S, 200 V / div.
Time Scale: 1 ms / div.
Zoom Time Scale: 10 s / div.
Page 20 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
10.2 Drain Voltage and Current Start-up Profile
Device has a built in soft-start thereby reducing the stress in the device, transformer and
output diode.
Figure 16 – 195 VAC / 50 Hz, 60 V LED String.
Ch1, Z1: VBULK, 100 V / div.
Ch2, Z2: VS-G, 100 V / div.
Ch3, Z3: IDRAIN, 0.5 A / div.
F1: VD-S, 200 V / div.
Time Scale: 2 ms / div.
Zoom Time Scale: 5 s / div
Page 21 of 33
Figure 17 – 195 VAC / 50 Hz, 60 V LED String.
Ch1, Z1: VBULK, 100 V / div.
Ch2, Z2: VS-G, 100 V / div.
Ch3, Z3: IDRAIN, 0.5 A / div.
F1: VD-S, 200 V / div.
Time Scale: 2 ms / div.
Zoom Time Scale: 5 s / div
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
10.3 Output Voltage Start-up Profile
Start-up time <50 ms; the reference design will emit light within 50 ms at non-dimming
operation.
Figure 18 – 195 VAC / 50 Hz, 60 V LED.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 100 ms / div.
Figure 19 – 220 VAC / 50 Hz, 60 V LED.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 100 ms / div.
Figure 20 – 240 VAC / 50 Hz, 60 V LED.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 100 ms / div.
Figure 21 – 265 VAC / 50 Hz, 60 V LED.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 100 ms / div.
Power Integrations, Inc.
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Page 22 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
10.4 Input and Output Voltage and Current Profiles
Output current ripple is inversely proportional to the impedance of the LED. Verify the
current ripple on the actual LED to be used in the system. Increase output capacitance
for less output current ripple.
Figure 22 – 195 VAC / 50 Hz, 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 10 ms / div.
Figure 23 – 220 VAC / 50 Hz, 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 10 ms / div..
Figure 24 – 240 VAC / 50 Hz, 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 10 ms / div.
Figure 25 – 265 VAC / 50 Hz, 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch3: IIN, 200 mA / div.
Ch4: IOUT, 100 mA / div., 10 ms / div..
Page 23 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
10.5 Drain Voltage and Current Profile: Normal Operation to Output Short
No saturation in the inductor during short-circuit, inductor current is limited by the ILIM.
Figure 26 – 195 VAC / 50 Hz, Normal Operation
then Output Short.
Ch1: VOUT, 20 V / div.
Ch3: IDRAIN, 0.5 A / div., 1 ms / div.
Z3: IDRAIN, 0.5A / div., 5 s / div.
Figure 27 – 265 VAC / 50 Hz, Normal Operation
then Output Short.
Ch1: VOUT, 20 V / div.
Ch3: IDRAIN, 0.5 A / div., 1 ms / div.
Z3: IDRAIN, 0.5A / div., 5 s / div.
10.6 Drain Voltage and Current Profile: Start-up with Output Shorted
No saturation in the inductor during start-up short-circuit due to the built-in soft-start.
Figure 28 – 195 VAC / 50 Hz, Output Shorted.
Ch1: VOUT, 100 V / div.
Ch3: IDRAIN, 0.5 A / div, 100 s / div.
Z3: IDRAIN, 0.5 A / div., 500 ns / div.
Power Integrations, Inc.
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Figure 29 – 265 VAC / 50 Hz, Output Shorted.
Ch1: VOUT, 100 V / div.
Ch3: IDRAIN, 0.5 A / div, 10o s / div.
Z3: IDRAIN, 0.5 A / div., 500 ns / div..
Page 24 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
10.7 No-Load Operation
One shot no-load protection. Replace VR1 after fault condition.
Figure 30 – 195 VAC / 50 Hz, Start-up No-load.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 0.1 A / div.
Time Scale: 100 ms / div.
Figure 31 – 265 VAC / 50 Hz, Start-up No-load.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 0.1 A / div.
Time Scale: 100 ms / div.
Figure 32 – 195 VAC / 50 Hz, Normal Running then
No-load.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 0.1 A / div.
Time Scale: 100 ms / div.
Figure 33 – 265 VAC / 50 Hz, Normal Running then
No-load.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 0.1 A / div.
Time Scale: 100 ms / div.
Page 25 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
10.8 AC Cycling
The reference design has no perceptible delay.
Figure 34 – 230 VAC / 50 Hz,
50 ms On – 50 ms Off.
Load: 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 100 mA / div.
Time Scale: 500 ms / div.
Figure 35 – 230 VAC / 50 Hz,
100 ms On – 100 ms Off.
Load: 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 100 mA / div.
Time Scale: 500 ms / div.
Figure 36 – 230 VAC / 50 Hz,
150 ms On – 150 ms Off.
Load: 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 100 mA / div.
Time Scale: 500 ms / div.
Figure 37 – 230 VAC / 50 Hz,
300 ms On – 300 ms Off.
Load: 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 100 mA / div.
Time Scale: 500 ms / div.
Power Integrations, Inc.
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Page 26 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
10.9 Brown-out
No device failure during the test. UUT operates normally within operating input voltage
range.
Figure 38 – 230 VAC / 50 Hz,1 V / s Slew Rate.
Load: 60 V LED String.
Ch1: VIN, 200 V / div.
Ch2: VOUT, 20 V / div.
Ch4: IOUT, 100 mA / div.
Time Scale: 50 s / div.
Page 27 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
10.10 Line Surge
Input voltage was set at 230 VAC / 60 Hz. Output was loaded with 60 V LED string and
operation was verified following each surge event.
Differential input line 1.2 / 50 s surge testing was completed on one test unit to
IEC61000-4-5.
Surge Level
(V)
+500
-500
+500
-500
Input
Voltage
(VAC)
230
230
230
230
Injection
Location
L to N
L to N
L to N
L to N
Injection
Phase
(°)
0
270
90
180
Test Result
(Pass/Fail)
Pass
Pass
Pass
Pass
Differential input line ring surge testing was completed on one test unit to IEC61000-4-5.
Surge Level
(V)
+2500
-2500
+2500
-2500
Input
Voltage
(VAC)
230
230
230
230
Injection
Location
L to N
L to N
L to N
L to N
Injection
Phase
(°)
0
270
90
180
Test Result
(Pass/Fail)
Pass
Pass
Pass
Pass
Unit operated normally under all test conditions.
Power Integrations, Inc.
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Page 28 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
11 Conducted EMI
11.1 Equipment
Receiver:
Rohde & Schwartz
ESPI - Test Receiver (9 kHz – 3 GHz)
Model No: ESPI3
LISN:
Rohde & Schwartz
Two-Line-V-Network
Model No: ENV216
11.2 EMI Test Set-up
The LED driver is placed in a conical metal housing (for self-ballasted lamps; CISPR15
Edition 7.2).
Figure 39 – Conducted Emissions Measurement Set-up.
Page 29 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
11.3 EMI Test Result
Power Integrations
16.Sep 13 13:59
RBW
MT
9 kHz
500 ms
Att 10 dB AUTO
dBµV
100 kHz
120
EN55015Q
110
1 QP
CLRWR
LIMIT CHECK
1 MHz
PASS
10 MHz
SGL
100
90
2 AV
CLRWR
TDF
80
70
60
EN55015A
50
6DB
40
30
20
10
0
-10
-20
9 kHz
30 MHz
Figure 40 – Conducted EMI, 60 V Output / 150 mA Steady-State Load, 230 VAC, 60 Hz, and EN55015
Limits.
Power Integrations, Inc.
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Page 30 of 33
05-Dec-13
Trace1:
DER-388 9 W Buck Power Supply Using LNK457DG
EDIT PEAK LIST (Final Measurement Results)
EN55015Q
Trace2:
EN55015A
Trace3:
---
TRACE
FREQUENCY
LEVEL dBµV
DELTA LIMIT dB
2
Average
99.0133127137 kHz
39.20
L1 gnd
1
Quasi Peak
196.231331718 kHz
56.71
L1 gnd
-7.05
2
Average
200.175581485 kHz
47.55
L1 gnd
-6.04
1
Quasi Peak
292.161713188 kHz
51.74
L1 gnd
-8.71
2
Average
298.034163623 kHz
40.09
L1 gnd
-10.19
1
Quasi Peak
389.890938834 kHz
48.52
N gnd
-9.54
2
Average
393.789848222 kHz
37.68
L1 gnd
-10.29
1
Quasi Peak
806.126927408 kHz
47.99
N gnd
-8.00
2
Average
806.126927408 kHz
34.40
N gnd
-11.59
1
Quasi Peak
908.363999266 kHz
49.07
N gnd
-6.92
2
Average
908.363999266 kHz
35.32
L1 gnd
-10.67
1
Quasi Peak
983.628047757 kHz
46.57
N gnd
-9.42
1
Quasi Peak
1.31265544283 MHz
49.15
N gnd
-6.84
2
Average
1.31265544283 MHz
36.65
L1 gnd
-9.34
2
Average
1.36595451756 MHz
37.14
L1 gnd
-8.85
1
Quasi Peak
1.37961406273 MHz
52.43
L1 gnd
-3.56
2
Average
1.46448812765 MHz
36.52
L1 gnd
-9.47
1
Quasi Peak
1.49392433901 MHz
50.23
N gnd
-5.76
1
Quasi Peak
1.66672409735 MHz
44.78
N gnd
-11.21
2
Average
5.02963192899 MHz
33.42
N gnd
-16.57
Figure 41 – Conducted EMI, 60 V / 150 mA Steady-State Load Steady-State Load, 230 VAC, 60 Hz, and
EN55015 Limits. Line and Neutral Scan Design Margin Measurement.
Page 31 of 33
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DER-388 9 W Buck Power Supply Using LNK457DG
05-Dec-13
12 Revision History
Date
05-Dec-13
Author
JDC
Revision
1.0
Description and Changes
Initial Release
Power Integrations, Inc.
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Reviewed
Apps & Mktg
Page 32 of 33
05-Dec-13
DER-388 9 W Buck Power Supply Using LNK457DG
For the latest updates, visit our website: www.powerint.com
Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability.
Power Integrations does not assume any liability arising from the use of any device or circuit described herein. POWER
INTEGRATIONS MAKES NO WARRANTY 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 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.
The PI Logo, TOPSwitch, TinySwitch, LinkSwitch, LYTSwitch, DPA-Switch, PeakSwitch, CAPZero, SENZero, LinkZero, HiperPFS,
HiperTFS, HiperLCS, Qspeed, EcoSmart, Clampless, E-Shield, Filterfuse, StackFET, PI Expert and PI FACTS are trademarks of
Power Integrations, Inc. Other trademarks are property of their respective companies. ©Copyright 2013 Power Integrations,
Inc.
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