Design Example Report

Transcription

1 Design Example Report Title Specification Application Author Document Number 0.7W Power Supply using LNK353P Input: VAC Output: 7V / 0.A TV Back Channel Power Supply Applications Department DER-09 Date October 26, 2005 Revision.0 Summary and Features Low cost, low part count solution (only 8 components) <50 mw no-load input power Meets EN and CISPR-22 Class B EMI with no Y safety capacitor Optimized switching speed yields excellent radiated EMI performance Small EE3 core size The products and applications illustrated herein (including circuits external to the products and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to. A complete list of patents may be found at Hellyer Avenue, San Jose, CA 9538 USA.

2 Table Of Contents Introduction Power Supply Specification Schematic Circuit Description Input and EMI Filtering Output Rectification and Filtering PCB Layout Bill Of Materials Transformer Specification Electrical Diagram Electrical Specifications Materials Transformer Build Diagram Performance Data Load and Line Regulation Thermal Performance Waveforms Output Voltage Start-up Profile Output Ripple Measurements Ripple Measurement Technique Measurement Results... Conducted EMI...2 Important Notes: Although this board is designed to satisfy safety isolation requirements, the engineering prototype has not been agency approved. Therefore, all testing should be performed using an isolated source to provide power to the prototype board. Design Reports contain a power supply design specification, schematic, bill of materials, and transformer documentation. Performance data and typical operation characteristics are included. Typically only a single prototype has been built. Page 2 of 4

3 Introduction This document is an engineering report describing a single input, 0.7W output power supply utilizing a LinkSwitch-HF LNK353P device. The document contains the power supply specification, schematic, bill of materials, transformer documentation, printed circuit layout, and performance data. Figure Populated Circuit Board Photograph Page 3 of 4

4 2 Power Supply Specification Description Symbol Min Typ Max Units Comment Input Voltage V IN VAC 2 Wire no P.E. Frequency f LINE Hz No-load Input Power (230 VAC) W Output Output Voltage V OUT 7 V ± 0% Output Ripple Voltage V RIPPLE 50 mv 20 MHz bandwidth Output Current I OUT 0. A Total Output Power Continuous Output Power P OUT 0.7 W Efficiency η 60 % Measured at P OUT (0.7 W), 25 o C Environmental Conducted EMI Meets CISPR22B / EN55022B >5 db margin Designed to meet IEC950, UL950 Safety Class II External Ambient Temperature T AMB 0 50 o C Free convection, sea level Page 4 of 4

5 3 Schematic L RF W D N4937 C5 2.2 uf 400 V L 2700 uh R6 00 k C9 nf kv D3 N4937 C2 2.2 uf 400 V D S U LNK353P FB BP N.C. T EE3 PC87D U2B 8 5 D2 UF4002 L2 3.3 uh C3 220 uf 0 V VR N5234B 6.2V R W U2A PC87D C6 00 uf 0 V 7V,00mA 0V C7 00 nf 50 V N Figure 2 Schematic 4 Circuit Description A simple, low cost, 0.7 W power supply is achieved with minimum parts count - made possible by the LinkSwitch power device. The integrated 700 V switching MOSFET and On/Off control function achieve high efficiency operation without a bias winding. The EE3 transformer uses a bobbin with extended creepage to meet safety spacing requirements. The transformer operating flux density is low (250 Gauss, 25 mt) to reduce audio emissions, due to On/Off control, to acceptable levels. This combined with standard dip varnishing of the transformer virtually eliminates audible noise. 4. Input and EMI Filtering AC input differential filtering is accomplished with a filter formed by C5/C2 and L. The inductor L is sleeved to also allow it to function as a fuse. An additional diode may be added to the Neutral phase in applications where lower EMI margins and/or an increased input surge withstand is required. 4.2 Output Rectification and Filtering Output rectification and filtering is achieved with output rectifier D2 and filter capacitor C3. Page 5 of 4

6 5 PCB Layout Figure 3 Printed Circuit Layout. (Not all parts are fitted due to Spec. change.) 6 Bill Of Materials Item Qty Value Description Part Reference Mfg Mfg Part Number 220 uf 220 uf, 0 V, Electrolytic, Low ESR, (6.3 x ) C3 Rubycon 0YXG220M6.3X uf 2.2 uf, 400 V, Electrolytic, (8 x.5) C5 C2 United Chemi-Con SMG400VB2R2M8XLL 3 00 uf 00 uf, 0 V, Electrolytic, Gen. Purpose, (5 x ) C6 United Chemi-Con KME0VB0M5XLL 4 00 nf 00 nf, 50 V, Ceramic, X7R C7 Panasonic ECU-SH04KBB 5 nf nf, kv, Disc Ceramic C9 Panasonic ECK-D3A02KBP 6 2 N V, A, Fast Recovery Diode, 200 ns, DO-4 D D3 Vishay N UF V, A, Ultrafast Recovery, 50 ns, DO-4 D2 Vishay UF uh 2700 uh, 80 ma, 40 Ohm, Axial Ferrite Inductor L Epcos B7848-S275-J uh 3.3 uh, A, Iron Core L2 API Delevan K Ohm Fusible Resistor, 2.5W RF R, 5%, /8 W, Carbon Film R2 Yageo CFR-2JB-220R 2 00 k 00 k, 5%, /4 W, Carbon Film R6 Yageo CFR-25JB-00K 3 EE3 Bobbin, EE3, Horizontal, 8 pins T Hical Magnetics 4 LNK353P LinkSwitch-HF, LNK353P, DIP-8B U LNK353P 5 PC87D Opto coupler, 35 V, CTR %, 4-DIP U2 Isocom, Sharp ISP87D, PC87X4 6 N5234B 6.2 V, 5%, 500 mw, DO-35 VR Microsemi N5234B Page 6 of 4

7 7 Transformer Specification 7. Electrical Diagram 2 Primary 80 Turns 0.5mm Magnet Wire 4 Balance 5 Turns 2*0.20mm Magnet Wire bifilar 2 Core 2 Turns 2*0.5mm Magnet Wire N.C. bifilar 3 EE3 8 7V 5 Turns 0.25mm Triple Isolated Wire 5 Figure 4 Transformer Electrical Diagram 7.2 Electrical Specifications Electrical Strength 60 Hz min, from Pins 2-3 to Pins VAC Primary Inductance From pins 3-2, all other windings open 650 uh, -/+2% Primary Leakage Inductance From pins 3-2 with and 5-8 shorted 30 µh (Max.) 7.3 Materials Item Description [] Core: EE3, PC40EE3, TDK ALG 02 nh/t 2 [2] Bobbin: Horizontal 8 pin [3] Magnet Wire: 0.5mm [4] Magnet Wire: 0.2mm [5] Triple Insulated Wire: 0.25mm [6] Tape: 3M 298 Polyester Film (white) 7.9mm wide by 2.2 mils thick [7] Varnish (dip) Page 7 of 4

8 7.4 Transformer Build Diagram PIN 8 PIN 5 PIN 4 PIN PIN 2 PIN 3 PIN 2 N.C. 7V Secondary Winding Balance Winding TAPE Primary Winding Core Shield Figure 5 Transformer Build Diagram Page 8 of 4

9 8 Performance Data All measurements performed at room temperature, 50 Hz input frequency. 8. Load and Line Regulation 5 4 Tolerance of Nom. Value in % Input Voltage in V Figure 6 Line Regulation, Room Temperature 5 4 Tolerance of NOM. Value in % Load Percent of NOM. Load in % Figure 7 Load Regulation, Room Temperature Page 9 of 4

10 9 Thermal Performance (Measured with Testo Infrared Thermometer) Temperature ( C) Item 95 VAC 265 VAC Ambient Transformer (T) LinkSwitch (U) Resistor (R6) Rectifier (D2) Waveforms 0. Output Voltage Start-up Profile Figure 8 Start-up Profile, 230 VAC V OUT, 2 V & ms / div. Page 0 of 4

11 0.2 Output Ripple Measurements 0.2. Ripple Measurement Technique A ripple probe, which included.0 µf Aluminum electrolytic capacitor in parallel with 0.µF ceramic capacitor, was used for all ripple measurements. The probe was located at the end of the DC output cable assembly. Figure 9 Oscilloscope Probe with Probe Master 525BA BNC Adapter. (Modified with wires for probe ground for ripple measurement, and two parallel decoupling capacitors added.) Measurement Results Figure 0 Ripple, 95 VAC, Full Load. 00us, 0 mv / div Figure Ripple, 265 VAC, Full Load. 00us, 0 mv / div Page of 4

12 Conducted EMI Figure 2 Conducted Emissions without Artificial Hand QP/AVG: 230 VAC, Full load, Neutral Figure 3 Conducted Emissions without Artificial Hand QP/AVG: 230 VAC, Full load, Line Page 2 of 4

13 Revision History Date Author Revision Description & changes Reviewed HM.0 Initial Release KM/JC/VC Page 3 of 4

14 For the latest updates, visit our website: 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. A complete list of patents may be found at. grants its customers a license under certain patent rights as set forth at The PI Logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, EcoSmart, PI Expert and PI FACTS are trademarks of, Inc. Other trademarks are property of their respective companies. Copyright 2005, Inc. Worldwide Sales Support Locations WORLD HEADQUARTERS 5245 Hellyer Avenue San Jose, CA 9538, USA. Main: Customer Service: Phone: Fax: usasales@powerint.com GERMANY Rueckertstrasse 3 D-80336, Munich Germany Phone: Fax: eurosales@powerint.com JAPAN Keihin Tatemono st Bldg Shin-Yokohama, Kohoku-ku, Yokohama-shi, Kanagawa ken, Japan Phone: Fax: japansales@powerint.com TAIWAN 5F, No. 38, Nei Hu Rd., Sec. Nei Hu Dist. Taipei, Taiwan 4, R.O.C. Phone: Fax: taiwansales@powerint.com CHINA (SHANGHAI) Rm A, Pacheer Commercial Centre, 555 Nanjing Rd. West Shanghai, P.R.C Phone: Fax: chinasales@powerint.com INDIA 26/A, Ground Floor 7th Main, 7th Cross, Sadashivanagar Bangalore, India Phone: Fax: indiasales@powerint.com KOREA RM 602, 6FL Korea City Air Terminal B/D, 59-6 Samsung-Dong, Kangnam-Gu, Seoul, , Korea Phone: Fax: koreasales@powerint.com EUROPE HQ st Floor, St. James s House East Street, Farnham Surrey, GU9 7TJ United Kingdom Phone: +44 (0) Fax: +44 (0) eurosales@powerint.com CHINA (SHENZHEN) Room , Block A, Elec. Sci. Tech. Bldg Shennan Zhong Rd. Shenzhen, Guangdong, China, 5803 Phone: Fax: chinasales@powerint.com ITALY Via Vittorio Veneto Bresso MI Italy Phone: Fax: eurosales@powerint.com SINGAPORE 5 Newton Road, #5-08/0 Goldhill Plaza, Singapore, Phone: Fax: singaporesales@powerint.com APPLICATIONS HOTLINE World Wide APPLICATIONS FAX World Wide Page 4 of 4