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 1/33 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 DocID025107 Rev 1 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 DocID025107 Rev 1 3/33 33 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 5/33 33 6/33 &21 - ) $9IDVW DocID025107 Rev 1 10 1$ 5 & %' +'7 & 10 '0* 5 / P+ 5 N: & Q) 9; 5 N: / P+ & Q) 9 ; 5 10 ' %=9& ' 5 4 00%7$ 5 5 5 & Q) 9 '5$,1 '5$,1 '5$,1 '5$,1 ' 677+/ & Q) 5 1$ & Q) & 5 10 & & Q) 9&& 5 5 5 5 $X[ 3ULB'UDLQ '0* ' 1 9&& 6285&( , 1$ &203 '0* /(' *1' &6 5 & 5 5 5 8 +9/('3) 5 3ULB5HFW 9 & Q) 9 7 & ' 6HF 67368 9 & 9 & & & Q) 10 - $0 &21 - &21 & 5 10 9287 1 &21 - 9,1 Demonstration board details AN4346 Demonstration board details Figure 2. EVLHVLED815W10F circuit diagram AN4346 Demonstration board details Figure 3. Component layout DocID025107 Rev 1 7/33 33 Demonstration board details AN4346 Figure 4. PCB layout 8/33 DocID025107 Rev 1 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 DocID025107 Rev 1 MCMSF 1 A 250 V 9/33 33 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 10/33 DocID025107 Rev 1 AN4346 2 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%. DocID025107 Rev 1 11/33 33 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. 12/33 DocID025107 Rev 1 AN4346 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. DocID025107 Rev 1 13/33 33 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. 14/33 DocID025107 Rev 1 AN4346 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. DocID025107 Rev 1 15/33 33 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. 16/33 DocID025107 Rev 1 AN4346 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. DocID025107 Rev 1 17/33 33 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) DocID025107 Rev 1 AN4346 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). DocID025107 Rev 1 19/33 33 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) DocID025107 Rev 1 AN4346 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.). DocID025107 Rev 1 21/33 33 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 + 4f l R LEDtot C o 1 + 4 50Hz R LEDtot 3 330F 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 DocID025107 Rev 1 AN4346 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. DocID025107 Rev 1 23/33 33 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. 24/33 DocID025107 Rev 1 AN4346 Electrical waveform Figure 30. ILED pin modulation with the input mains voltage 9,1 '5$,1 5$&B+ ,UHI ,/(' &/(' 5$&B/ 5$&B/ 2)) 5 &ILOWHU /RJLF '(0$* /2*,& 6: 5 6 && 3:0 /2*,& 4 4 ,)) '0* $8; 5'0* 5)) /RJLF IHHGIRUZDUG 5)% &6 6285&( 5VHQVH $0 DocID025107 Rev 1 25/33 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 DocID025107 Rev 1 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. DocID025107 Rev 1 27/33 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 DocID025107 Rev 1 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. DocID025107 Rev 1 29/33 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. 30/33 DocID025107 Rev 1 AN4346 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 DocID025107 Rev 1 31/33 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 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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