AN2173 APPLICATION NOTE Using a VIPer12-based Power Supply to Replace a Wall Transformer Introduction This application note describes a power supply that can be used as a wall transformer replacement or as a power module for a small consumer appliance. The design objectives are: ■ The outside case dimensions (in inches) are 2L x 2W x 1H, with smaller inside dimensions, ■ the Line and Neutral pins (of equal size and 8mm from the end of the assembly) are attached to the case, ■ the input voltage ranges are 95VAC to 135VAC; and 190VAC to 270VAC, ■ the output voltage is 15V (max) at 1mA (min) and is 12V (min) at 500mA (max), with a 50% duty cycle, ■ the ambient temperature range is –5°C to 55°C, and ■ the Electromagnetic Interference (EMI) is measured for all loads. The power supply for the wall transformer replacement application consists primarily of a re-packaged VIPer12 Demonstration Board (12V, single output voltage, see Application Note AN1734 for details). Figure 1. VIPer12-based Power Supply Assembly, Top View November 2005 Rev 1.0 1/15 http:/www.st.com 15 AN2173 - APPLICATION NOTE Table of Contents 1 VIPer12-based Power Supply Features and Assembly . . . . . . . . . . . . . . . 4 1.1 Layout and Component Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Heat Sink Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Operation Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Transformer Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4 Transformer Mechanical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Appendix A. Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Appendix B. KIDDE VIPer12 Demo Board BOM . . . . . . . . . . . . . . . . . . . . 13 5 2/15 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 AN2173 - APPLICATION NOTE 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. VIPer12-based Power Supply Assembly, Top View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 PCB Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 PCB Component Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 EMI Measurements (EMI EN5502, Class B). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Heat Sink Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Drain to Source Voltage (Vds ) and Drain Current (Id) Waveforms . . . . . . . . . . . . . . . . . . . . 8 Power Supply Efficiency with Line Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Line Regulation: Power Supply Output Voltage vs. Varied Input Line Voltage. . . . . . . . . . . 9 Load Regulation: Power Supply Output Voltage vs. Varied Load . . . . . . . . . . . . . . . . . . . . 9 Transformer Winding Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Transformer Mechanical Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 VIPer12-based Power Supply Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3/15 1 VIPer12-based Power Supply Features and Assembly 1 1.1 AN2173 - APPLICATION NOTE VIPer12-based Power Supply Features and Assembly ● Fixed 60kHz Switching Frequency ● Switch mode General Purpose Power Supply ● Burst Mode Operation in Standby for Blue Angel operation ● Current Mode Control ● Typical 75% Efficiency at Full Load ● Auxiliary Undervoltage Lockout with Hysteresis ● Output Short Circuit Protection ● Thermal Shutdown Protection ● Meets EN55022 Class B EMI specification Layout and Component Placement To meet Printed Circuit Board (PCB) space requirements, both sides of the PCB are used for either low or high voltage power supply mains by selecting the appropriate voltage rating for the bulk capacitors and the Metal Oxide Varistor (MOV). Surface-mount components should be used wherever possible to reduce the size of the assembly. The remaining axial lead devices (e.g., resistors, diode, and “pigtail” fuse) are mounted vertically to save PCB space. The line and neutral pins are molded into the bottom of the case and pass through two holes in the top of the case, and a line cord attachment is on the side opposite the line and neutral pins (see Figure 2 on page 5 and Figure 3 on page 5). The PCB size is determined by the overall dimensions and the side wall thicknesses of the case (1.78in x 1.78in, with rectangular mounting slots in each side). A 0.118in mounting hole is provided. Additional support using 0.75in PCB standoffs is recommended, with the component leads trimmed to 0.65in (max). See Appendix A. Schematics on page 12 and Appendix B. KIDDE VIPer12 Demo Board BOM on page 13 for details. 4/15 AN2173 - APPLICATION NOTE 1.2 1 VIPer12-based Power Supply Features and Assembly Assembly The initial PCBs and power supply assemblies were routed, built, and tested in the lab. An assembly fits into the case with the attached output wire cable that is connected from the flange to the end. If a Pollution Degree 1 rating is desired, the assembly should be in a sealed case, since the cable runs from the secondary (across the transformer) to the primary. Additionally, the transformer can be smaller if the case is sealed. If a sealed case is not used, then thicker insulation or triple-insulated wire may be required. Assembly EMI (EN5502, Class B) measurements are shown in Figure 4 on page 6. Figure 2. PCB Layout Figure 3. PCB Component Placement 5/15 1 VIPer12-based Power Supply Features and Assembly Figure 4. 6/15 EMI Measurements (EMI EN5502, Class B) AN2173 - APPLICATION NOTE AN2173 - APPLICATION NOTE 1.3 1 VIPer12-based Power Supply Features and Assembly Heat Sink Enhancement The smaller layout, though useful for PCB space savings, is also prone to heat sink area reduction. To enhance the cooling capacity for the VIPer12, mounting a small heat sink directly in the holes with the 4 DRAIN pins in the VIPer12’s DIP package is recommended (see Figure 5). Figure 5. Heat Sink Configuration 7/15 AN2173 - APPLICATION NOTE 2 Operation Characteristics 2 Operation Characteristics Figure 6. Drain to Source Voltage (Vds) and Drain Current (Id) Waveforms Note: Measured during normal operation with an input line of 115VAC and the output at full load. Figure 7. Power Supply Efficiency with Line Variation 78 Efficiency (%) 77 76 75 74 73 72 80 90 100 110 120 130 Input Line Voltage (VAC) Note: Measured at full load, when the line is varied from 85VAC to 137VAC. 8/15 140 AI11834 AN2173 - APPLICATION NOTE Figure 8. 2 Operation Characteristics Line Regulation: Power Supply Output Voltage vs. Varied Input Line Voltage Output Voltage (VO) 12.2 12.18 12.16 12.14 12.12 12.1 80 90 100 110 120 130 Input Line Voltage (VAC) 140 AI11835 Note: Power supply output voltage is monitored while running at full load, and the line is varied from 85VAC to 134VAC. Figure 9. Load Regulation: Power Supply Output Voltage vs. Varied Load Output Voltage (VO) 12.2 12.18 12.16 12.14 12.12 12.1 0.00 0.10 0.20 0.30 Load (A) 0.40 0.50 0.60 AI11836 Note: Power supply output voltage is monitored while running at 115VAC, and the load is varied from 0.01A to 0.51A. 9/15 AN2173 - APPLICATION NOTE 3 Transformer Electrical Specifications 3 Transformer Electrical Specifications When the VIPer12A (U4) is ON, energy is stored in the primary winding of transformer (10-8), TR1. This energy is transferred to the auxiliary winding (5-6), and to the output (1-2) when the VIPer12A is OFF. The auxiliary winding provides the bias voltage for the VIPer12A at pin 4 (VDD). Figure 10. Transformer Winding Schematic 8 120 - 400V @ 60kHz, 50% DC N1 9 TR1 1 N2 12V @ 0.50A 2 N4 10 5 N3 15V @ 0.02A 1/2 Primary Auxiliary Secondary 1/2 Primary 6 AI11837 Table 1. Winding Inductance Ratings Parameter Primary Inductance (Lp) Primary Leakage Inductance (L lp) 10/15 Value Units 3.25 ± 10% mH 34 (typ) µH AN2173 - APPLICATION NOTE 4 4 Transformer Mechanical Information Transformer Mechanical Information Figure 11. Transformer Mechanical Drawing 0.71 (max) 0.71 (max) 0.19 REF 0.022 (typ) 0.13 ± 0.02 (3x) 0.055 REF 1 4 0.48 ± 0.02 0.65 (max) 10 5 0.10 ± 0.02 (5x) AI11838 11/15 95 to 135VAC VIN* Line Neutral R1 C1 = 1.0µF/400V C2 = 10µF/400V R1 = 4.7Ω 1/4W CC MOV = 440V *For 190 to 270VAC: Jumper C11 0.047µF MOV 220V 2 BR1 SM C1 4.7µF/250V 1 HJC0308Q L1 2 3 4 3 1 2 5.1Ω Fusable Resistor 1 4 F1 C2 10µF/250V C4 22µF/25V R2 2k 1/2W 1 2 8 7 6 5 C3 HS Fb VDD VIPer12A SOURCE SOURCE DRAIN DRAIN DRAIN DRAIN U4 47pF 1kV 3 4 R8 BAV20WS D2 4.7 R3 9.1k 6 8 5 6 8 5 C6 47nF TR1 3.3nF 250V Y1 C5 CVP11-021 2 1 2 1 2 D3 1 U3 TL431 3 R7 3.40k 1% C9 0.01µF R5 1k C7 330µF/25V C8 330µF/25V U2 H11A817A R4 220 STTH102 4 3 10 1 2 1 12/15 2 10 RTN 12.1V R6 13.3k 1% R9 3.3k Appendix A. Schematics AN2173 - APPLICATION NOTE Appendix A. Schematics Figure 12. VIPer12-based Power Supply Schematics AI11184 AN2173 - APPLICATION NOTE Appendix B. KIDDE VIPer12 Demo Board BOM Appendix B. KIDDE VIPer12 Demo Board BOM Table 2. Domestic Bill of Materials Qty Reference Part Description Manufacturer Manufacturer Part Number 1 BR1 SM Bridge 600V 1.5A Diodes, Inc. DF1506S-T 1 C1 4.7uF/250V Electro Panasonic ECA-2EHG4R7 1 C2 10uF/250V Electro Panasonic ECA-2EHG100 1 C3 47pF 1kV Ceramic Panasonic ECC-D3A470JGE 1 C4 22uF/25V Electro Panasonic ECA-1EM220 1 C5 3.3nF 250V Y1 Panasonic ECK-ATS332ME 1 C6 47nF SMD 1206 2 C7, C8 330uF/25V Electro Panasonic EEU-FC1E331L 1 C9 0.01uF 0805 Panasonic ECJ-2VB1H103K 1 C11 0.047uF 250V Box Panasonic ECQ-U2A473ML 1 D2 200V .2A Micro Commercial BAV20WS-TP 1 D3 200V 1A STMicroelectronics STTH102 1 F1 5.1 Ohm Fusable Resistor 1 L1 Common Mode Hua Jung Comp. HJC0308Q 1 R1 JUMPER 1 R2 2K 5% 1/2W 1 R3 9.1K 5% 1206 1 R4 220 5% 805 1 R5 1K 5% 0805 1 R6 13.3K 1% SMD 0805 Panasonic ERJ-6ENF1332V 1 R7 3.40K 1% SMD 0805 Panasonic ERJ-6ENF3401V 1 R8 4.7 5% 1206 1 R9 3.3K 5% 1206 1 TR1 Output transformer Cramer Coil CVP11-021 1 U2 H11A817A Fairchild H11A817A 1 U3 TL431 STMicroelectronics TL431AIZ 1 U4 VIPer12A Dip STMicroelectronic VIPer12ADIP 1 MOV 220V Varistor 1 HS U4 Heat Sink 2 AC Wires 1 Output cable assembly 13/15 AN2173 - APPLICATION NOTE 5 Revision History 5 14/15 Revision History Date Revision 11-November-2005 1.0 Changes First edition AN2173 - APPLICATION NOTE 5 Revision History Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. 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