dm00092673

AN4346
Application note
10 W wide range - high power factor - isolated LED driver using
HVLED815PF
By Giovanni Gritti
Introduction
This application note describes the performances of an isolated 10 W, wide range, regulated
LED driver using the HVLED815PF device, with a high power factor and a constant output
current regulation. Main input specifications are:

Input voltage:

Isolated solution (flyback topology)

Output power:
10 W

Output LED voltage (typ.):
22 V

Output LED current (typ.):
455 mA

Power factor:
> 0.95

LED driver efficiency:
up to 84%
88 - 265 Vac
The architecture is based on a single stage isolated flyback and it has been used the
STMicroelectronics® HVLED815PF device with primary side control to achieve a LED
current regulation within ± 5% and a high power factor.
The form factor has been designed to fit into a standard lighting case making easy the
replacement of the incandescent lamp.
Figure 1. EVLHVLED815W10F demonstration board
October 2013
DocID025107 Rev 1
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www.st.com
Contents
AN4346
Contents
1
Demonstration board details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
Measurement results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3
2.1
Driver efficiency at nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2.2
Power factor at nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3
Line regulation at nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.4
Total harmonic distortion (THD) at nominal load . . . . . . . . . . . . . . . . . . . 13
2.5
Driver efficiency at different LED load number . . . . . . . . . . . . . . . . . . . . . 13
2.6
Power factor at different LED load number . . . . . . . . . . . . . . . . . . . . . . . 14
2.7
Line regulation at different LED load number . . . . . . . . . . . . . . . . . . . . . . 14
2.8
Total harmonic distortion (THD) at different LED load number . . . . . . . . . 15
2.9
Harmonic content at nominal mains voltage . . . . . . . . . . . . . . . . . . . . . . 16
2.10
Overvoltage protection in no load condition . . . . . . . . . . . . . . . . . . . . . . . 17
2.11
Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Electrical waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.1
Input and output LED driver waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2
Transition mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3
ILED pin modulation with the input mains voltage . . . . . . . . . . . . . . . . . . . 24
3.4
Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.5
Startup at no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.6
OVP protection to a load disconnection . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.7
Output short-circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4
Support material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2/33
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AN4346
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Bill of material (BOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Top side 88 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Top side 100 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Top side 230 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Top side 265 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Bottom side 88 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Bottom side 100 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Bottom side 230 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Bottom side 265 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
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List of figures
AN4346
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
Figure 43.
Figure 44.
Figure 45.
Figure 46.
Figure 47.
Figure 48.
4/33
EVLHVLED815W10F demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
EVLHVLED815W10F circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Component layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
LED driver efficiency versus AC line voltage at nominal load. . . . . . . . . . . . . . . . . . . . . . . . 8
Power factor (PF) at nominal load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Average output current versus line voltage at nominal load . . . . . . . . . . . . . . . . . . . . . . . . . 9
Total harmonic distortion (THD) versus line voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
LED driver efficiency versus AC line voltage at different numbers of LEDs applied. . . . . . 10
Power factor (PF) at different LED load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Average output current versus line voltage at different numbers of LEDs applied . . . . . . . 11
Total harmonic distortion (THD) versus line voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Harmonic content at 100 Vac/50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Harmonic content at 230 Vac/50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
OVP voltage vs. input mains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Top side temperature POUT = 10 W - 88 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Top side temperature POUT = 10 W - 100 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Top side temperature POUT = 10 W - 230 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Top side temperature POUT = 10 W - 265 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Bottom side temperature POUT = 10 W - 88 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Bottom side temperature POUT = 10 W - 100 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Bottom side temperature POUT = 10 W - 230 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Bottom side temperature POUT = 10 W - 265 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Input and output LED driver waveforms at 100 Vac - 50 Hz. . . . . . . . . . . . . . . . . . . . . . . . 19
Input and output LED driver waveforms at 230 Vac - 50 Hz. . . . . . . . . . . . . . . . . . . . . . . . 19
ILED pin operation at 100 Vac - 50 Hz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Transition mode operation at 100 Vac - 50 Hz - zoom on the peak - fsw = 51 kHz . . . . . . 20
ILED pin operation at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Transition mode operation at 230 Vac - 50 Hz - zoom on the peak - fsw = 83 kHz . . . . . . 20
ILED pin modulation with the input mains voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
ILED pin operation at 88 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ILED pin operation at 100 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ILED pin operation at 130 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ILED pin operation at 175 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ILED pin operation at 230 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
ILED pin operation at 265 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Startup at 100 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Startup at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Startup at 100 Vac - 50 Hz - no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Startup at 230 Vac - 50 Hz - no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Load disconnection at 100 Vac -50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
No load behavior at 100 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Load disconnection at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
No load behavior at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Short-circuit behavior at 100 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
After short-circuit at 100 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Short-circuit behavior at 30 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
After short-circuit at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
DocID025107 Rev 1
AN4346
Figure 49.
Figure 50.
List of figures
Short-circuit removal at 100 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Short-circuit removal at 230 Vac - 50 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
DocID025107 Rev 1
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Demonstration board details
AN4346
Demonstration board details
Figure 2. EVLHVLED815W10F circuit diagram
AN4346
Demonstration board details
Figure 3. Component layout
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Demonstration board details
AN4346
Figure 4. PCB layout
8/33
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AN4346
Demonstration board details
)
Ref.
Table 1. Bill of material (BOM)
Value
Description
Manufacturer
Manuf. part number
BD1
HD06-T
Diode bridge HD06-T 600 V 0.8 A
MINIDIP
DIODES® Inc.
HD06-T
C1
33 nF
CAP 33 nF X2 305 V MKP P.10
EPCOS
B32921C3333M
C2
220 nF
CAP 220 nF X2 305 V MKP P.15
EPCOS
B32922C3224M
C3
1 nF
Cap. 1 nF ± 10% X7R 630 V 1206
TDK
C3216X7R2J102K115AA
C4
100 nF
Cap. 100 nF ± 10% X7R 50 V 0805
KEMET
C0805C104K5RACTU
C5
4.7 F
Cap. 4.7 F ± 10% X5R 25 V 0805
KEMET
C0805C475K3PACTU
C6
470 nF
Cap. 470 nF ± 10% X7R 25 V 0805
KEMET
C0805C474K3RACTU
C7
2.2 nF
Cap. 2.2 nF ± 5% C0G 50 V 0805
MURATA
GRM2165C1H222JA01D
C8
47 F
Cap. 47 F ± 20% EL. 50V 105 °C
rad. D5 P 2 mm
Panasonic
EEUFR1H470
C10
1 nF
CAP 1 nF X1 Y1 250 V CERAMIC
P. 10
MURATA
DE1E3KX102MN5A
C11, C12,
330 F
C16
Cap. 330 F ± 20% EL. 35 V 105 °C
LL LOW ESR rad. D10 P5mm
Nichicon
UHE1V331MPD
C13
100 nF
Cap. 100 nF ± 10% X7R 50 V 1206
KEMET
C1206C104K5RACTU
C17
5.6 nF
Cap. 5.6 nF ± 5% C0G 50 V 0805
MURATA
GRM2195C1H562JA01D
C19
4.7 F
Cap. 4.7 F ± 10% X5R 50 V 1206
TAIYO YUDEN
UMK316BJ475KL-T
D1
STTH1L06
Diode rect. UFAST STTH1L06U
600 V 1 A SMB
STMicroelectronics® STTH1L06U
D2
1N4148
Diode rect. fast 1N4148 75V 150 mA
SOD123
Vishay®
1N4148W-V-GS08
D3
STPS3150U
Diode Schottky STPS3150U 150 V
3 A SMB
STMicroelectronics
STPS3150U
D4
120 k
Res. 100 k 1/4 W 1% 100 ppm 1206
SMD
CRCW1206120KFKEA
D7
BZV55-C20
Zener 20 V ± 5% 500 mW MINIMELF NXP
BZV55-C20
F1
1 A 250 V fast
Fuse 1 A 250 V fast radial 8.4 mm x
7.7 mm P 5 mm
L1, L2
1 mH
Choke RF 1 mH 370 mA axial D 6.5 L
EPCOS
12 mm
B82145A1105J000
Q2
MMBTA42
NPN SML SIG G.P. AMP SOT23
MMBTA42
R1
270 k
Res. 270 k 1/4 W 1% 100 ppm 1206
SMD
CRCW1206270KFKEA
R2
1
Res. 1  1/4 W 1% 100 ppm 1206
SMD
CRCW12061R00FKEA
R4
120 k
Res. 120 k 1/8 W 1% 100 ppm 0805
SMD
CRCW0805120KFKEA
Multicomp
Electronic
Components
STMicroelectronics
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Demonstration board details
AN4346
Table 1. Bill of material (BOM)
Ref.
Value
Description
Manufacturer
Manuf. part number
R5
16 k
Res. 16 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080516K0FKEA
R7, R12
10 k
Res. 10 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080510K0FKEA
R8
91 k
Res. 91 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080591K0FKEA
R9
68 
Res. 68  1/8 W 1% 100 ppm 0805
SMD
CRCW080568R0FKEA
R10
62 k
Res. 62 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080562K0FKEA
R13
120 k
Res. 120 k 1/4 W 1% 100 ppm 1206
SMD
CRCW1206120KFKEA
R15, R17 180 k
Res. 180 k 1/4 W 1% 100 ppm 1206
SMD
WCR1206-180KFI
R16
0
Res. 0  0603 SMD
CRCW06030000Z0EA
R20
15 k
Res. 15 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080515K0FKEA
R21
51 k
Res. 51 k 1/8 W 1% 100 ppm 0805
SMD
CRCW080551K0FKEA
R22
6.2 k
Res. 6.2 k 1/8 W 1% 100 ppm 0805
SMD
CRCW08056K20FKEA
R23, R24 4.7 k
Res. 4.7 k 1/8 W 1% 100 ppm 0805
SMD
CRCW08054K70FKEA
T1
1855.0005
Transformer flyback 15 W
Lp = 1.5 mH Np = 190 Ns = 42
Naux = 24 core EF20
Magnetica
1855.0005
U1
HVLED815PF
Offline LED driver HVLED815PF
SO16
STMicroelectronics
HVLED815PF
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Measurement results
Measurement results
The HVLED815PF LED driver demonstration board has been tested using the following
instrumentation/load:


2.1
CHROMA® 61602
AC source
®
YOGOGAWA WT210
wattmeter
®

Tektronix DP07054 500 MHz
digital oscilloscope

Tektronix TCP0030
current probe

LeCroy PPE4kV 100:1 400 MHz
high voltage probe

KEITHLEY 2000
digital multimeter

Avio TVS-200 P
thermal video system

SEOUL SEMICONDUCTOR Z-POWER LED P4 LED series
Driver efficiency at nominal load
In Figure 5 is displayed LED driver efficiency versus the AC line voltage at a nominal load.
Figure 5. LED driver efficiency versus AC line voltage at nominal load
As shown in Figure 5 LED driver efficiency is up to 84%.
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Measurement results
2.2
AN4346
Power factor at nominal load
In Figure 6 is displayed the measured power factor (PF) at a nominal load:
Figure 6. Power factor (PF) at nominal load
As shown in Figure 6 the power factor (PF) is over 0.95 in all the input voltage range
[88 - 265] Vac.
2.3
Line regulation at nominal load
In Figure 7 is displayed the measured average output current versus line voltage at
a nominal load.
Figure 7. Average output current versus line voltage at nominal load
The output current is 455 mA ± 0.8% over all the input voltage range [88 - 265] Vac.
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2.4
Measurement results
Total harmonic distortion (THD) at nominal load
In Figure 8 is displayed the total harmonic distortion (THD) versus line voltage.
Figure 8. Total harmonic distortion (THD) versus line voltage
The THD at nominal input voltage is lower than 20%.
2.5
Driver efficiency at different LED load number
In Figure 9 is displayed LED driver efficiency versus AC line voltage at different numbers of
LEDs applied.
Figure 9. LED driver efficiency versus AC line voltage at different numbers of LEDs
applied
As shown in Figure 9 LED driver efficiency is always over 80% in all the input voltage range
also varying the number of LEDs.
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Measurement results
2.6
AN4346
Power factor at different LED load number
In Figure 10 is displayed the measured power factor (PF) at a different LED load.
Figure 10. Power factor (PF) at different LED load
As shown in Figure 10 the power factor (PF) is over 0.90 in all the input voltage range
[88 - 265] Vac also varying the number of LEDs.
2.7
Line regulation at different LED load number
In Figure 11 is displayed the measured average output current versus line voltage at
different numbers of LEDs applied.
Figure 11. Average output current versus line voltage at different numbers of LEDs
applied
The output current is varying ± 3% changing the load over all the input voltage range
[88 - 265] Vac.
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2.8
Measurement results
Total harmonic distortion (THD) at different LED load number
In Figure 12 is displayed the total harmonic distortion (THD) versus line voltage.
Figure 12. Total harmonic distortion (THD) versus line voltage
The THD at nominal input voltage is lower than 20% applying different loads.
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Measurement results
2.9
AN4346
Harmonic content at nominal mains voltage
One of the main benefits of the HVLED815PF device is the correction of input current
distortion, decreasing the harmonic contents below the limits of the relevant regulations.
Figure 13 and Figure 14 show the harmonic content at 100 Vac/50 Hz and 230 Vac/50 Hz
input voltage.
The measurement at 100 Vac, 50 Hz; PIN = 12.1 W; POUT = 10 W; PF = 0.994:
Figure 13. Harmonic content at 100 Vac/50 Hz
The measurement at 230 V, 50 Hz; PIN = 11.8 W; POUT = 9.9 W; PF = 0.963:
Figure 14. Harmonic content at 230 Vac/50 Hz
Figure 13 and Figure 14 show as the harmonics respect the limits for Class C equipment.
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2.10
Measurement results
Overvoltage protection in no load condition
In the EVLHVLED815W10F demonstration board the OVP protection has been set at 30
VDC typ.
Regulated output voltage during no load condition can be fixed by selecting properly RDMG
and RFB (see the HVLED815PF datasheet) by Equation 1.
Equation 1
N s R DMG
Ns
42 91k
42
V OUT = ------------  ----------------  V REF + V REF  ------------ = ------  ---------------  2.51V + 2.51V  ------ = 30V
N aux R FB
N aux 24 16k
24
OVP voltage vs. input mains is represented in Figure 15.
Figure 15. OVP voltage vs. input mains
Waveforms of LED driver behavior are shown in Section 3: Electrical waveform on page 22.
2.11
Thermal measurements
To check reliability of design, the thermal maps have been checked with an IR camera.
The LED driver has been stressed at the nominal LED load number (POUT = 10 W) all over
the input mains voltage range. Only the minimum, maximum voltage range and the two
nominal mains voltage 100/50 Hz and 230/50 Hz have been reported.
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Measurement results
AN4346
Figure 16. Top side temperature POUT = 10 W - 88 V
Table 2. Top side 88 V
Point
Temp.
Comment
A
77.3 °C
Winding transformer (T1)
B
62.1 °C
Magnetic transformer (T1)
C
55.5 °C
Lin (L1)
Figure 17. Top side temperature POUT = 10 W - 100 V
Table 3. Top side 100 V
18/33
Point
Temp.
Comment
A
73.5 °C
Winding transformer (T1)
B
58.7 °C
Magnetic transformer (T1)
C
49.8 °C
Lin (L1)
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Measurement results
Figure 18. Top side temperature POUT = 10 W - 230 V
Table 4. Top side 230 V
Point
Temp.
Comment
A
69.2 °C
Winding transformer (T1)
B
57.1 °C
Magnetic transformer (T1)
C
47.6 °C
Lin (L1)
Figure 19. Top side temperature POUT = 10 W - 265 V
Table 5. Top side 265 V
Note:
Point
Temp.
Comment
A
69.9 °C
Winding transformer (T1)
B
57.6 °C
Magnetic transformer (T1)
C
48.9 °C
Lin (L1)
Temperatures have been taken after stable thermal condition (after 60 min).
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Measurement results
AN4346
Figure 20. Bottom side temperature POUT = 10 W - 88 V
Table 6. Bottom side 88 V
Point
Temp.
Comment
A
78.9 °C
IC controller (U1)
B
72.4 °C
Snubber resistor (R1)
C
58.7 °C
Output diode (D3)
Figure 21. Bottom side temperature POUT = 10 W - 100 V
Table 7. Bottom side 100 V
20/33
Point
Temp.
Comment
A
67.5 °C
IC controller (U1)
B
66.1 °C
Snubber resistor (R1)
C
58.2 °C
Output diode (D3)
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Measurement results
Figure 22. Bottom side temperature POUT = 10 W - 230 V
Table 8. Bottom side 230 V
Point
Temp.
Comment
A
62.0 °C
Partition resistor (D4)
B
60.5 °C
IC controller (U1)
C
61.0 °C
Snubber resistor (R1)
D
57.3 °C
Output diode (D3)
Figure 23. Bottom side temperature POUT = 10 W - 265 V
Table 9. Bottom side 265 V
Note:
Point
Temp.
Comment
A
69.7 °C
Partition resistor (D4)
B
63.0 °C
IC controller (U1)
C
63.3 °C
Snubber resistor (R1)
D
57.9 °C
Output diode (D3)
Temperatures have been taken after stable thermal condition (after 60 min.).
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Electrical waveform
AN4346
3
Electrical waveform
3.1
Input and output LED driver waveforms
The waveforms of the input current and drain voltage at the nominal input voltage mains and
nominal LED load are illustrated in this section. Drain voltage is modulated by the sinusoidal
shape of the input mains voltage and the peak increase with the line.
The input current is in phase with the input voltage and a high power factor is achieved.
Figure 24. Input and output LED driver
waveforms at 100 Vac - 50 Hz
CH1: DRAIN pin
CH2: INPUT CURRENT
CH3: VOUT
CH4: LED CURRENT
Figure 25. Input and output LED driver
waveforms at 230 Vac - 50 Hz
CH1: DRAIN pin
CH2: INPUT CURRENT
CH3: VOUT
CH4: LED CURRENT
Also the LED current and output voltage have been checked.
Note that the regulated LED current remains constant all over the input mains voltage.
The LED pk-pk ripple is the ± 27% of the average current. Increasing the value of the output
capacitor it is possible to decrease the LED current ripple following Equation 2:
Equation 2
2  I OUT
2  455mA
I ripple  ----------------------------------------------------------------------- = ----------------------------------------------------------------------------------------------------------------2
2
1 +  4f l  R LEDtot  C o 
1 +  4  50Hz  R LEDtot   3  330F  
For this demonstration 3 parallel capacitors of 330 F have been selected to have a current
ripple of 250 mA pk-pk with 7 LEDs each with a dynamic resistance of 0.8 
22/33
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3.2
Electrical waveform
Transition mode operation
During ON-time, the peak drain current is modulated by a signal proportional to the ILED pin.
This reference sets the turn-off of the MOSFET.
The MOSFET turn-on depends on the DMG signal that senses demagnetization of the drain
current realizing a transition mode operation.
Figure 26. ILED pin operation at 100 Vac - 50 Hz Figure 27. Transition mode operation at 100 Vac
- 50 Hz - zoom on the peak - fsw = 51 kHz
CH1: DRAIN pin
CH2: CS pin
CH3: ILED pin
CH4: DMG pin
CH1: DRAIN pin
CH2: CS pin
CH3: ILED pin
CH4: DMG pin
Figure 28. ILED pin operation at 230 Vac - 50 Hz Figure 29. Transition mode operation at 230 Vac
- 50 Hz - zoom on the peak - fsw = 83 kHz
CH1: DRAIN pin
CH2: CS pin
CH3: ILED pin
CH4: DMG pin
CH1: DRAIN pin
CH2: CS pin
CH3: ILED pin
CH4: DMG pin
A primary inductance of 1.5 mH has been selected in order to obtain the converter switching
frequency into the interval [45 - 90] kHz.
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Electrical waveform
3.3
AN4346
ILED pin modulation with the input mains voltage
Referring to Figure 30, a voltage VX proportional to the input rectified mains is summed on
the average voltage present on the ILED pin trough the CLED capacitor generating
a voltage reference proportional to the input voltage (AC coupling).
Equation 3
V X = V IN
pk – pk
R AC L
 ---------------------------------------R AC H + R AC L
The ILED pin voltage is internally divided (Gi) and then compared with the CS pin voltage,
generating a primary current proportional to the input voltage reaching the high power factor
condition.
The average value of ILED pin is not depending from the VIN input voltage (AC coupling), as
a consequence the desiderated output current can be programed trough the current sense
resistor Rsense in according to the following relationship (see the HVLED815PF datasheet
for more details).
Equation 4
I LED
190
---------n V CLED
42 0.2V
= ---  ------------------ = ----------  ------------- = 0.453A
2 R sense
2
1.0
where n is the primary-to-secondary transformer ratio (n = Np/Ns = 190/42), VCLED the
equivalent internal voltage (VCLED(typ) = 0.2 V) that include R, Iref parameters.
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Electrical waveform
Figure 30. ILED pin modulation with the input mains voltage
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DocID025107 Rev 1
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33
Electrical waveform
AN4346
Figure 31 to Figure 36 show the behavior of the ILED pin depending on the action of the
switch represented by the BJT Q2 (SW in Figure 30, Q2 in Figure 2 on page 6). At low line
the switch is off (BJT base is low) and the pin is modulated by the divider composed by
RAC_H and RAC_L1. When, at high line, the BJT is ON the pin ILED is modulated by a
different ratio of the divider (RAC_H and the parallel of RAC_L1 with RAC_L2) in order to keep
the same dynamic on the ILED pin.
The effect is a very sinusoidal shape at nominal mains voltage 100 Vac and 230 Vac with
high performance in terms of PF and THD.
Figure 31. ILED pin operation at 88 Vac
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor (see schematic)
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor
Figure 33. ILED pin operation at 130 Vac
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor
26/33
Figure 32. ILED pin operation at 100 Vac
Figure 34. ILED pin operation at 175 Vac
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor
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AN4346
Electrical waveform
Figure 35. ILED pin operation at 230 Vac
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor
3.4
Figure 36. ILED pin operation at 265 Vac
CH1: VIN
CH2: BJT base
CH3: ILED pin
CH4: C5 capacitor
Startup
With a VCC capacitor of 47 F, the HVLED815PF device turns-on in 100 ms (see Figure 37
and Figure 38). Light appears hundreds milliseconds later.
A capacitor C5 (4.7 F) on the ILED pin is charging during the start-up phase and it is
responsible of the LED current soft-start time.
Figure 37. Startup at 100 Vac - 50 Hz
CH1: LED current
CH2: CS pin
CH3: VOUT
CH4: VCC pin
Figure 38. Startup at 230 Vac - 50 Hz
CH1: LED current
CH2: CS pin
CH3: VOUT
CH4: VCC pin
Acting on this C5 capacitor, it is possible to modify the soft-start time. In detail, to speed up
the loop it is enough to reduce the C5 capacitor reducing the soft-start time.
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33
Electrical waveform
3.5
AN4346
Startup at no load
If the converter wakes-up during no load condition, the OVP protection is triggered and the
output voltage is regulated at 32 V, protecting the output electrolytic capacitors from high
voltage.
Figure 39. Startup at 100 Vac - 50 Hz - no load
CH1: LED current
CH2: CS pin
CH3: VOUT
CH4: VCC pin
28/33
Figure 40. Startup at 230 Vac - 50 Hz - no load
CH1: LED current
CH2: CS pin
CH3: VOUT
CH4: VCC pin
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AN4346
3.6
Electrical waveform
OVP protection to a load disconnection
During a load disconnection the HVLED815PF device senses the output voltage through the
DMG pin and controls the voltage loop in order to regulate the output capacitor voltage to
a level below its maximum rating.
Figure 41. Load disconnection at 100 Vac 50 Hz
CH1: DRAIN pin
CH2: IOUT
CH3: VOUT
CH4: DMG pin
CH1: DRAIN pin
CH2: IOUT
CH3: VOUT
CH4: DMG pin
Figure 43. Load disconnection at 230 Vac
- 50 Hz
CH1: DRAIN pin
CH2: IOUT
CH3: VOUT
CH4: DMG pin
Figure 42. No load behavior at 100 Vac - 50 Hz
Figure 44. No load behavior at 230 Vac - 50 Hz
CH1: DRAIN pin
CH2: IOUT
CH3: VOUT
CH4: DMG pin
As shown in Figure and Figure 44 the converter works in burst mode during no load
condition.
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33
Electrical waveform
3.7
AN4346
Output short-circuit
During a short of the output connector, all the energy stored in the output electrolytic
capacitor is discharged into the output side loop and no current will flow into the external
LED preventing their failure.
Figure 45. Short-circuit behavior at 100 Vac
- 50 Hz
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
Figure 47. Short-circuit behavior at 30 Vac
- 50 Hz
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
Figure 46. After short-circuit at 100 Vac - 50 Hz
Figure 48. After short-circuit at 230 Vac - 50 Hz
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
The converter is able to regulate the output current to a minimum level reducing the input
power during this fail.
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Electrical waveform
Converter is internally self supplying through the HVs generator.
If the short is removed, the output voltage comes back to its nominal value, the external
charging pump supplies the IC and the output current is regulated at its nominal value.
Figure 49. Short-circuit removal at 100 Vac
- 50 Hz
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
Figure 50. Short-circuit removal at 230 Vac
- 50 Hz
CH1: DRAIN pin
CH2: CS pin
CH3: VOUT
CH4: VCC pin
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33
Support material
4
AN4346
Support material
Documentation
HVLED815PF datasheet: “Offline LED driver with primary-sensing and high power factor up
to 15 W”.
5
Revision history
Table 10. Document revision history
32/33
Date
Revision
29-Oct-2013
1
Changes
Initial release.
DocID025107 Rev 1
AN4346
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