DAK-85

Engineering Prototype Report for EP-85 – 2 W Charger using LinkSwitch®-LP (LNK564P) Title Specification 90 – 265 VAC Input, 6 V, 330 mA Output Application Low Cost, Line Frequency Transformer Based Charger Replacement Author Power Integrations Strategic Marketing Department Document Number EPR-85 Date 04-Oct-2005 Revision 1.0 Summary and Features • • • • • • Low cost, low part count solution (only 14 components) • Proprietary IC and Circuit technology enable Clampless™ design and very simple Filterfuse™ input stage Integrated LinkSwitch-LP safety/reliability features • Over-temperature protection – tight tolerance (+/-5%) with hysteretic recovery for safe pcb temperature under all conditions • Auto-restart output short circuit and open-loop protection • Extended pin creepage distance for reliable operation in humid environments - >3.2 mm minimum at package EcoSmart® – Easily meets all existing and proposed international energy efficiency standards – China (CECP) / CEC / EPA / European Commission • No-load consumption 140 mW at 265 VAC • 64.9% average efficiency measured to CEC spec (versus target 55.2%) Ultra-low leakage current: 9 dBµV margin Meets IEC61000-4-5 Class 3 AC line surge Power Integrations 5245 Hellyer Avenue, San Jose, CA 95138 USA. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 04-Oct-2005 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 Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger Table of Contents 1 2 3 4 Introduction .................................................................................................................4 Power Supply Specification ........................................................................................6 Schematic ...................................................................................................................7 Circuit Description.......................................................................................................7 4.1 Input and EMI Filtering.........................................................................................7 4.2 LinkSwitch-LP Feedback .....................................................................................7 4.3 Primary Clamp and Transformer Construction ....................................................8 4.4 Output Rectification and Filtering.........................................................................8 4.5 Optional Components ..........................................................................................8 5 PCB Layout.................................................................................................................9 6 Bill Of Materials.........................................................................................................10 7 Transformer Specification .........................................................................................11 7.1 Electrical Diagram..............................................................................................11 7.2 Electrical Specifications .....................................................................................11 7.3 Materials ............................................................................................................12 7.4 Transformer Build Diagram................................................................................12 7.5 Design Spreadsheet ..........................................................................................14 8 Performance Data.....................................................................................................16 8.1 Efficiency ...........................................................................................................16 8.1.1 Active Mode CEC Measurement Data........................................................16 8.2 No-Load Input Power.........................................................................................17 8.3 Regulation .........................................................................................................17 9 Thermal Performance ...............................................................................................18 10 Waveforms ............................................................................................................20 10.1 Drain Voltage and Current, Normal Operation...................................................20 10.2 Output Voltage Start-Up Profile, Battery Load ...................................................21 10.3 Drain Voltage and Current Start-Up Profile........................................................22 10.4 Output Ripple Measurements ............................................................................23 10.4.1 Ripple Measurement Technique.................................................................23 10.4.2 Measurement Results.................................................................................24 11 Conducted EMI .....................................................................................................25 12 AC Line Surge.......................................................................................................27 13 Revision History ....................................................................................................28 Important Note: 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 isolation transformer to provide the AC input to the prototype board. Page 3 of 32 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 04-Oct-2005 1 Introduction This document describes a universal input charger power supply designed to replace linear transformer based chargers/adapters in low power applications. The power supply utilizes a LinkSwitch-LP IC, LNK564P. The document contains the power supply specification, schematic, bill of materials, transformer documentation, printed circuit layout, and performance data. The LinkSwitch-LP IC has been developed to replace linear transformers in low power charger applications. The integrated 700 V switching MOSFET and ON/OFF control function achieve very high efficiency operation under all load conditions with simple bias winding voltage feedback. No-load and operating efficiency performance exceeds all international energy efficiency standards either present or proposed in the future. Thermal shutdown is included as a minimum requirement to match the safety thermal cut out (thermal fuse) in linear transformers. The IC’s intelligent thermal shutdown feature is specified with a very tight tolerance (142 ˚C +/-5%) and includes a hysteretic autorecovery feature to automatically restart the power supply while maintaining the average pcb temperature at safe levels under all conditions. This auto-recovery is designed to eliminate the potential for field returns since the power supply automatically recovers when ambient temperatures return to the normal operating range. However, with latching thermal shutdown, often used in RCC discrete switching power supply designs, the input AC typically needs to be removed to reset the thermal latching function. With RCCs, there is therefore a potential that power supplies will be returned after a thermal latch off, as customers are often unaware of the need to reset by unplugging the power supply. The auto-recovery thermal shutdown also eliminates noise sensitivity associated with discrete latch circuits, which can be sensitive to circuit design, environmental conditions and component age. The IC package provides extended creepage distance between high and low voltage pins (both at the package and pcb), which is required in high humidity conditions to prevent arcing. Other features include pulsed auto-restart operation under output short circuit and open loop conditions. Worst-case no-load power consumption is approximately 140 mW at 265 VAC, well within the 300 mW European standards and even 150 mW at 230 VAC targets set in some customer specifications. Heat generation is minimized with high operating efficiency under all load and line conditions. The EE16 transformer bobbin provides extended creepage to meet safety spacing requirements. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 4 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger Figure 1 – LNK564 Low Cost Cell Phone Charger Populated Circuit Board Photograph. Page 5 of 32 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 04-Oct-2005 2 Power Supply Specification Description Input Voltage Frequency No-load Input Power Output Output Voltage Symbol Min VIN fLINE 90 47 5.5 VOUT1 VRIPPLE1 VRIPPLE2 VRIPPLE3 VRIPPLE4 Output Ripple Voltage VRIPPLE_TOTAL 0.3 IOUT1 Output Current Total Output Power Continuous Output Power POUT η Efficiency Typ Max Units Comment 265 63 0.15 VAC Hz W 2 Wire – no P.E. 6 200 200 200 400 800 0.33 V mVpp mVpp mVpp mVpp mVpp A 90VAC max. power point 2.0 W 57 % o 230 VAC, 25 C 0 – 20 Hz 20 Hz – 20 kHz 20 kHz – 200 kHz 200 kHz – 400 kHz Total combined 90 VAC, max. power point Measured at 115/230 VAC o Ave. 25/50/75/100% load, 25 C Environmental Conducted EMI Meets CISPR22B / EN55022B Safety Designed to meet IEC950, UL1950 Class II Surge Meets IEC61000-4-5 Class 3 External Ambient Temperature -5 TAMB 45 >6 dB margin C o Free convection, sea level 10 9 Ou tp u t Vo ltag e (V 8 7 6 5 4 3 2 1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 Output Current (A) Figure 2 – Low Cost Charger Output Envelope Specification. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 6 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger 3 Schematic Figure 3 – LNK564 Low Cost Charger Schematic. 4 Circuit Description 4.1 Input and EMI Filtering AC input differential filtering is accomplished with the very low cost input filter stage formed by C1 and L1. The proprietary frequency jitter feature of the LNK564 eliminates the need for an input pi filter, so only a single bulk capacitor is required. This allows the input inductor L1 to be used as a fuse as well as a filter component. This very simple Filterfuse input stage further reduces system cost. The L1 is sleeved to allow it to function as a fuse. An optional fusible resistor, RF1, may be used to provide the fusing function. Input diode D2 may be removed from the neutral phase in applications where decreased EMI margins and/or decreased input surge withstand is allowed. 4.2 LinkSwitch-LP Feedback The power supply utilizes simplified bias winding voltage feedback enabled by LNK564 ON/OFF control. The resistor divider formed by R1 and R2 determine the output voltage across the transformer bias winding during the switch off time. In the V/I constant voltage region, the LNK564 device enables/disables switching cycles to maintain 1.69 V on the FB pin. Diode D3 and low cost ceramic capacitor C3 provide rectification and filtering of the primary feedback winding waveform. At increased loads, beyond the constant power threshold, the FB pin voltage begins to reduce as the power supply output voltage falls. The internal oscillator frequency is linearly reduced in this region until it reaches typically 50% of the starting frequency when the FB pin voltage reaches the auto-restart threshold voltage (typically 0.8 V on the FB pin, which is equivalent to 1 V to 1.5 V at the output of the power supply). This function limits the output current in this region without fold back until the output voltage is low. Page 7 of 32 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 04-Oct-2005 No-load consumption can be further reduced by increasing C3 to 0.47 µF or higher. 4.3 Primary Clamp and Transformer Construction A Clampless primary circuit is achieved due to the very tight tolerance current limit trimming techniques used in manufacturing the LNK564, plus the transformer construction techniques used. Peak drain voltage is therefore limited to typically less than 550 V at 265 VAC – providing significant margin to the 700 V minimum drain voltage specification (BVDSS). 4.4 Output Rectification and Filtering Output rectification and filtering is achieved with output rectifier D4 and filter capacitor C5. Due to the auto-restart feature, the average short circuit output current is significantly less than 1 A, allowing low cost rectifier D4 to be used. Output circuitry is designed to handle a continuous short circuit on the power supply output. Diode D4 is an ultra-fast type, selected for optimum V/I output characteristics. Optional resistor R3 provides a pre-load, limiting the output voltage level under no-load output conditions. Despite this pre-load, no-load consumption is within targets at approximately 140 mW at 265 VAC. The additional margin of no-load consumption requirement can be achieved by increasing the value of R4 to 2.2 kΩ or higher while still maintaining output voltage well below the 9 V maximum specification. Placement is left on the board for an optional Zener clamp (VR1) to limit maximum output voltage under open loop conditions, if required. 4.5 Optional Components Fusible resistor RF1, VR1 and C4 are all optional components. Resistor RF1, VR1 and C4 are not fitted on the board as standard, RF1 being replaced with a wire link. • • • Resistor RF1 may be fitted to designs where a traditional fuse is preferred over the Filterfuse configuration. Zener diode VR1 is fitted where the output voltage must be limited to a lower value during open loop conditions. The auto-restart feature of LinkSwitch-LP limits the output power under this condition, requiring only a zener with a low, 0.5 W rating. The use of E-ShieldTM techniques in the transformer removes the need for a Y1 safety capacitor across the safety isolation barrier to meet EMI. However, the use of C4, a small value (100 pF) Y1 capacitor provides improved EMI consistency if transformer construction variation is a concern. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 8 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger 5 PCB Layout Figure 4 – LNK564 Low Cost Charger Printed Circuit Layout. Page 9 of 32 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 04-Oct-2005 6 Bill Of Materials Item Qty Ref Description Manufacturer 1 1 C1 10 µF, 400 V, Electrolytic, Low ESR, Ltec 79 mA, (10 x 12.5) 2 1 C2 100 nF, 50 V, Ceramic, Z5U Kemet 3 1 C3 330 nF, 50 V, Ceramic, X7R Panasonic 4* 1 C4 100 pF, Ceramic, Y1 Vishay 5 1 C5 220 µF, 25 V, Electrolytic, Very Low ESR, United Chemi-Con 72 mΩ, (8 x 11.5) 6 1 D1 600 V, 1 A, Fast Recovery Diode, Vishay 200 ns, DO-41 7 2 D2 D3 600 V, 1 A, Rectifier, DO-41 Vishay 8 1 D4 100 V, 1 A, Ultrafast Recovery, 50 ns, Vishay DO-41 9 2 J1 J2 Test Point Keystone 10 1 J3 6 ft, 22 AWG, 0.25 Ω, 2.1 mm Generic Epcos 11 1 L1 3300 µH, 62 mA, 59.5 Ω, Axial Ferrite Inductor 12 1 - Heatshrink tubing, 3/16” diameter, 0.5” length Generic 13 1 R1 37.4 kΩ, 1%, 1/4 W, Metal Film Yageo 14 1 R2 3 kΩ, 5%, 1/8 W, Carbon Film Yageo 15 1 R3 2 kΩ, 5%, 1/8 W, Carbon Film Yageo 16** 1 RF1 8.2 Ω, 2.5 W, Fusible/Flame Proof Wire Vitrohm Wound 17 1 T1 Bobbin, EE16, Horizontal, 10 pins Ngai Cheong Electronics Assembled unit available from Falco Hical CWS Li Shin Woo Jin 18 1 U1 LinkSwitch-LP, LNK564P, DIP-8B Power Integrations 19* 1 VR1 10 V, 5%, 500 mW, DO-35 Microsemi Manufacturer Part # TYD2GM100G13O C317C104M5U5CA ECU-S1H334KBB 440LT10 KZE25VB221MH11LL 1N4937 1N4005 UF4002 5011 B78108S1335J Generic MFR-25FBF-37K4 CFR-12JB-3K0 CFR-12JB-2K0 CRF253-4 5T 8R2 EE-16 10PINs E09077 SIL6036 CWS-T1-DAK85 LSLA40342 SLP-2218P1 LNK564P 1N5240B *Optional component ** Optional components - not fitted replaced with jumper on board Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 10 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger 7 Transformer Specification 7.1 Electrical Diagram 5 WDG #1 Bias 2 Primary 6 Cut WDG #3 Shield 0.25 mm × 3 8T 0.14 mm 108T 1 Secondary WDG #4 0.5 mm T.I.W. 8T 0.2 mm 25T 4 WDG #2 7 2 : Winding Start, forward winding direction : Winding Start, reversed winding direction Figure 5 – Transformer Electrical Diagram. 7.2 Electrical Specifications Electrical Strength Primary Inductance Primary Winding Capacitance Primary Leakage Inductance Page 11 of 32 60 Hz 1 min, from pins 1-5 to pins 6-7 From pins 1-2, all other windings open All windings open From pins 1-2 with pins 6-7 shorted 3000 VAC 2.7 mH, -/+5% 50 pF (Max.) 75 µH (Max.) Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 7.3 Materials Item [1] [2] [3] [4] [5] [6] [7] [8] [9] 7.4 04-Oct-2005 Description Core : EE16, PC40EE13, TDK – ALG 230 nH/T2 Bobbin: Horizontal 10 pin – pins 3, 8, 9, and 10 removed Magnet Wire: 0.20 mm Polyurethane coated class 2 wire Magnet Wire: 0.14 mm Polyurethane coated class 2 wire Magnet Wire: 0.25 mm Polyurethane coated class 2 wire Triple Insulated Wire: 0.5 mm Tape: 3M 1298 Polyester Film (white) 320 mils wide by 1 mil thick Barrier Tape: 2 mm width Varnish (dip) Transformer Build Diagram Iso. Tape Secondary 0.5 mm T.I.W. 8T 7 6 Iso. Tape 2 * Shield 0.25 mm × 3 8T 2 Iso. Tape Primary 0.14 mm 1 Bias 0.2 mm Iso. Tape 4 5 Barrier tape 2 mm * See Fig. 7 for detail of shield winding start technique. Figure 6 – Transformer Build Diagram. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 12 of 32 04-Oct-2005 EP-85 6 V, 330 mA Low Cost Charger 2 mm margin tape 1/4T to set winding start position. Start winding here from edge of margin tape. Plastic tape Position three wires to line up with outside edge of margin tape and stick wires down with plastic tape. No empty space among the wires. Figure 7 – Winding Method of Shield Winding. Page 13 of 32 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-85 6 V, 330 mA Low Cost Charger 7.5 04-Oct-2005 Design Spreadsheet INPUT ACDC_LinkSwitchLP_091605; Rev.1.0; Copyright Power Integrations 2005 ENTER APPLICATION VARIABLES VACMIN 90 VACMAX 265 fL 50 VO 6.00 INFO OUTP UNIT UT Volts Volts Hertz Volts EP85 Design Minimum AC Input Voltage Maximum AC Input Voltage AC Mains Frequency Output Voltage (main) measured at the end of output cable (For CV/CC designs enter typical CV tolerance limit) Power Supply Output Current (For CV/CC designs enter typical CC tolerance limit) Enter "YES" for CV/CC output. Enter "NO" for CV only output IO 0.33 Constant Voltage / Constant Current Output Output Cable Resistance PO Feedback Type YES CVCC Volts 0.05 BIAS Add Bias Winding YES Clampless design YES n 0.70 Z tC 0.50 2.80 0.05 Ohms Enter the resistance of the output cable (if used) 1.99 Watts Output Power (VO x IO + dissipation in output cable) Bias Winding Enter 'BIAS' for Bias winding feedback and 'OPTO' for Optocoupler feedback Yes Enter 'YES' to add a Bias winding. Enter 'NO' to continue design without a Bias winding. Addition of Bias winding can lower no load consumption Clamp Enter 'YES' for a clampless design. Enter 'NO' if an external less clamp circuit is used. Efficiency Estimate at output terminals. For CV only designs enter 0.7 if no better data available 0.5 Loss Allocation Factor (Secondary side losses / Total losses) mSecond Bridge Rectifier Conduction Time Estimate s uFarads Input Capacitance H Choose H for Half Wave Rectifier and F for Full Wave Rectification CIN Input Rectification Type 10.00 H ENTER LinkSwitch-LP VARIABLES LinkSwitch-LP LNK564 Chosen Device ILIMITMIN ILIMITMAX fSmin I^2fMIN I^2fTYP VOR VDS VD KP Amps ACDC_LinkSwitch-LP_091605_Rev1-0.xls; LinkSwitch-LP Continuous/Discontinuous Flyback Transformer Design Spreadsheet LinkSwitch-LP device LNK564 0.124 0.146 93000 1665 Amps Amps Hertz A^2Hz 1850 A^2Hz 88.00 88 Volts 10 Volts 0.5 Volts 1.54 ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES Core Type EE16 Core EE16 P/N: Bobbin EE16_BOBBIN P/N: AE 0.192 cm^2 LE 3.5 cm AL 1140 nH/T^2 BW 8.6 mm M 0 mm L NS NB VB R1 8 2 8 27 21.93 Volts 36.89 k-ohms Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Minimum Current Limit Maximum Current Limit Minimum Device Switching Frequency I^2f Minimum value (product of current limit squared and frequency is trimmed for tighter tolerance) I^2f typical value (product of current limit squared and frequency is trimmed for tighter tolerance) Reflected Output Voltage LinkSwitch-LP on-state Drain to Source Voltage Output Winding Diode Forward Voltage Drop Ripple to Peak Current Ratio (0.9