AN4419 Application note VIPER37HE: 15 W wide range single output evaluation board By Fabio Cacciotto Introduction This application note describes a 15 W wide range evaluation board, based on Viper37HE, which is designed as an example of an isolated auxiliary power supply. The board and the transformer were designed and optimized in order to have a very compact size evaluation board. February 2014 DocID025645 Rev 1 1/18 www.st.com Contents AN4419 Contents 1 Test board: design and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Output voltage characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.2 Efficiency and light load measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.3 No-load and light load consumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.4 Typical board waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 Conducted noise measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5 Evaluation tools and documentation . . . . . . . . . . . . . . . . . . . . . . . . . . 16 6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2/18 DocID025645 Rev 1 AN4419 Test board: design and evaluation 1 Test board: design and evaluation Table 1 summarizes the electrical specification of the power supply, Table 2 provides the BOM and Table 4 lists transformer's spec. The electrical schematic is shown in Figure 2 and the PCB layout in Figure 3 and Figure 4. Table 1. VIPer37H evaluation board electrical specification Parameter Min. Typ. Max. Unit AC Main Input voltage 100 265 VAC Mains frequency (fL) 50 60 Hz 12.3 V 1.25 A 50 mV Output Voltage 11.7 12 V Output Current Output ripple voltage Rated output power 15 W 50 Input power in standby @ 230VAC Active mode efficiency mW 78 % Ambient operating temperature 60 °C Figure 1. Electrical schematic L1 T1 + L2 12V-1.25A 3.3uH 1mH BR RMB6S D6 STPS5H100UF C2 15uF C3 15uF C4 1nF R1 220k C9 470uF C10 100uF C11 1uF - D1 STTH1L06A 3 2 D4 BAT41ZFILM D3 GND R7 1k BAT41ZFILM R2 4.7 R3 133K 4 1 CM 2X20mH R12 2.2M C1 D2 BAT41ZFILM OPTO SFH610A-2 R8 12k IC1 220nF - X2 VIPER37HE NTC 16 C5 220pF RV VDD DRAIN R10 130k BR 320V R5 220 F1 C6 33uF R9 82k CONTROL CONT 2A FB GND C12 10nF D5 18V AC IN AC IN R4 30k C8 33nF IC2 TS432 C7 2.2nF R6 47k OPTO SFH610A-2 R11 15k C13 2.2nF DocID025645 Rev 1 AM18323v1 3/18 18 Test board: design and evaluation AN4419 Figure 2. Evaluation board (30 x 72 mm) max AM18336v1 Table 2. VIPer37H evaluation board: bill of material Reference Part Description Note R1 220 kΩ 0.33 W – 200 V R2 4.7 Ω 1% tolerance R3 133 kΩ 1% tolerance R4 30 kΩ 1% tolerance R5 220 Ω 0.25 W R6 47 kΩ 1% tolerance R7 1 kΩ R8 12 kΩ R9 82 kΩ 1% tolerance R10 130 kΩ 1% tolerance R11 15 kΩ 1% tolerance R12 2.2 MΩ 1% tolerance C1 BFC233920224 220 nF - 275 V x 2 Vishay C2, C3 450BXF15M10X20 15 μF - 450 V electrolytic Rubycon C4 C3216C0G2J102JT 1 nF - 630 V MLCC TDK C5 GRM188R71H221KA01D 220 pF - 16 V MLCC Murata C6 35YXM33MEFC5X11 33 μF - 35 V electrolytic Rubycon C7 GRM1885C1H222FA01D 2.2 nF - 50 V MLCC Murata C8 GRM188R71H333KA61D 33 nF -16 V MLCC Murata C9 25ZLJ470M10X12.5 470 μF - 25 V electrolytic Rubycon 4/18 DocID025645 Rev 1 AN4419 Test board: design and evaluation Table 2. VIPer37H evaluation board: bill of material (continued) Reference Part Description Note C10 25YXJ100M5X11 100 μF - 25 V electrolytic Rubycon C11 GRM188C81E105KAADD 1 μF - 25 V MLCC Murata C12 GRM188R71H103KA01D 10 nF - 50 V MLCC Murata C13 DE2E3KY222MA2BM01 2.2 nF - 250 V X1/Y1 CAP Murata D1 STTH1L06A Ultra-fast diode 600 V - 1 A STMicroelectronics D2, D3, D4 BAT41ZFILM Signal Schottky diode STMicroelectronics D5 MMSZ5248B-V-GS08 18 V Zener diode Vishay D6 STPS5H100B Power Schottky 100 V - 5 A STMicroelectronics L1 B82144A2105J 1 mH Axial inductor Epcos L2 SD43-332ML 3.3 μH Power inductor Coilcraft CM 744821120 20 mH CM choke Wurth Elektronik IC1 VIPer37LE Offline HV converter STMicroelectronics IC2 TS432ILT 1.24 V Shunt voltage reference STMicroelectronics OPTO SFH610A-2 Optocoupler Vishay TF YJ-310V600210 Flyback transformer Yujing Technology BR RMB6S Bridge 600 V - 1 A Taiwan Semiconductor NTC B57236S160M NTC Inrush current limiter Epcos Fs 0461002.ER 2 A fuse Littlefuse Note: If not otherwise specified, all resistors are ± 5%, 0.1 . Table 3. Transformer characteristic Reference Description Manifacturer Yujing Technology CO. LTD. Part number YJ-310V600210 Core EEE - 13 V Ferrite 3C94 Ferroxcube Primary Inductance 0.85 mH ±10%. Leakage inductance 40 µH max Primary turns (N1+N3) 75 Secondary turns (N2) 12 Auxiliary turns (N4) 14 DocID025645 Rev 1 5/18 18 Test board: design and evaluation AN4419 Figure 3. Electrical scheme AM18338v1 Figure 4. Drawing transformer (mm.) AM18337v1 6/18 DocID025645 Rev 1 AN4419 1.1 Test board: design and evaluation Output voltage characteristics The output voltage of the board is measured in different line and load conditions. Figure 5 shows the results: the output voltage variation range is a few tens mV for all the tested conditions. All output voltages have been measured on the output connector of the board. Figure 5. Line and load regulation AM18324v1 12.3 Output voltage [V] 12.2 12.1 12.0 115 Vac 230 Vac 11.9 11.8 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Output current [mA] 1.2 Efficiency and light load measurements Any external power supply (EPS) must be capable to meet the international regulation agency limits. The European code of conduct (EC CoC) and US department of energy (DoEUS EISA 2007) limits are taken as reference. EPS limits are fixed up to 77.76%, when the average efficiency is measured. The average efficiency measures the average value at 25%, 50%, 75% and 100% of the rated output power, at both 115 VAC and 230 VAC. Figure 6 shows the results. DocID025645 Rev 1 7/18 18 Test board: design and evaluation AN4419 Figure 6. Efficiency vs. output power AM18325v1 88 86 84 Efficiency [%] 82 80 EC Code of Conduct 78 76 115 Vac 230 Vac average @ 115 Vac average @ 230 Vac 74 72 70 0 2 4 6 8 10 12 14 16 Output power [W] 1.3 No-load and light load consumptions No-load consumptions and light load consumption are two important parameters that must be considered when selecting the IC controller and very often they are the key parameters of choice. The presented board was optimized in order to provide an extremely low consumption at zero load but also in order to meet EµP Lot 6 energy saving regulation, which requires that the efficiency of the converter must be higher than 50% when the output is loaded with 250 mW. In Figure 7 and Figure 8 the consumption in the said condition are shown. Figure 7. No load consumption vs. input voltage AM18326v1 65 60 55 50 Input power [mW] 45 40 35 30 25 20 15 10 50 100 150 200 Input voltage [Vac] 8/18 DocID025645 Rev 1 250 300 AN4419 Test board: design and evaluation Figure 8. Light load consumptions at 250 mW O/P AM18327v1 500 Input power [mW] 450 400 250 mW 350 300 250 200 50 100 150 200 250 300 Input voltage [Vac] 1.4 Typical board waveforms In this section, typical waveforms are reported. Drain voltage and current waveforms were reported at nominal input voltages and full load in Figure 9 and Figure 10. The startup phase is shown in Figure 11 and Figure 12: the IC starts with very clean waveforms and no overshoot/undershoot appear on the output. Finally also the output voltage when the converter is submitted to dynamic load variations is measured, in order to be sure that good stability is ensured and no overvoltage on undervoltage occurs The board was submitted to dynamic load variations from 0% to 100% load (Figure 13 and Figure 14): no abnormal oscillations were noticed on the output and the over/under shoot were well within acceptable values. DocID025645 Rev 1 9/18 18 Test board: design and evaluation AN4419 Figure 9. Drain current and voltage at full load 115 VAC AM18328v1 I DS VDS Ch1 (Max): 340 V Ch2 (Max): 596.mA M: 4.0 µs/div Figure 10. Drain current and voltage at full load 230 VAC AM18329v1 I DS VDS Ch1 (Max): 517 V Ch2 (Max): 612 mA 10/18 DocID025645 Rev 1 M: 4.0 µs/div AN4419 Test board: design and evaluation Figure 11. Startup at full load and 115 VAC AM18330v1 VOUT VDD VD S Ch3 (Max): 12.04 V M: 40 ms/div Figure 12. Startup at full load and 230 VAC AM18331v1 VOUT VDD VD S Ch3 (Max): 12.06 V DocID025645 Rev 1 M: 40 ms/div 11/18 18 Test board: design and evaluation AN4419 Figure 13. Step load at 115 VAC AM18332v1 VOUT IOUT Ch1 (Max): 0 A Ch1 (Min): 1.26 A Ch2 (Max): 12.07 V Ch2 (Min): 11.73 V M: 20 .0 ms/div Figure 14. Step load at 230 VAC AM18333v1 VOUT IOUT Ch1 (Max): 0 A Ch1 (Min): 1.26 A 12/18 Ch2 (Max): 12. 06 V Ch2 (Min): 11.7 4 V DocID025645 Rev 1 M: 20 .0 ms/div AN4419 2 Conducted noise measurements Conducted noise measurements A pre-compliance test for EN55022 (Class B) European normative was performed using peak measurements detector of the conducted noise emissions at full load and nominal mains voltages. Figure 15 and Figure 16 show the results. As seen in the diagrams, in all test conditions there is a good margin for the measurements with respect to the AV and QP limits, also using the peak detector with max-hold function. Figure 15. CE average measurement at 115 VAC and full load AM18334v1 Figure 16. CE average measurement at 230 VAC and full load: Peak measurement AM18335v1 DocID025645 Rev 1 13/18 18 Thermal measurements 3 AN4419 Thermal measurements A thermal analysis of the board was performed using an IR camera. The board was submitted to full load at nominal input voltage and the thermal map was taken 30 min. after the power on at ambient temperature (25 °C). Figure 17, Figure 18, Figure 19 and Figure 20 show the results. Figure 17. Thermal map at 115 VAC and full load Figure 18. Thermal map at 115 VAC and full load top side bottom side Figure 19. Thermal map at 230 VAC and full load Figure 20. Thermal map at 230 VAC and full load top side bottom side 14/18 DocID025645 Rev 1 AN4419 4 Conclusions Conclusions A 15 W wide range single output flyback converter using the new VIPer37HE has been introduced and the results are presented. The transformer arrangement and the very compact sizes make the PSU suitable as external adapter or as an auxiliary power supply in all the applications where performances and dimensions are the main constrains. The efficiency performances were compared with requirements of the most important international regulation agencies for external AC-DC adapters, resulting in a wide margin respect the minimum required. DocID025645 Rev 1 15/18 18 Evaluation tools and documentation 5 AN4419 Evaluation tools and documentation The VIPer37LE evaluation board order code is: STEVAL-ISA140V1. Further information about this product are available in the VIPer37 datasheet at www.st.com. 16/18 DocID025645 Rev 1 AN4419 6 Revision history Revision history Table 4. Document revision history Date Revision 24-Feb-2014 1 Changes Initial release. DocID025645 Rev 1 17/18 18 AN4419 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. 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