DAK-71A

Engineering Prototype Report for EP-71 – 6.6 W DC-DC Converter Using DPA-Switch™ (DPA423G) Title Specification 36-72 VDC Input, 3.3 V, 2 A Output Application Standby Supply for Distributed Power Architectures Author Power Integrations Applications Department Document Number EPR-71 Date 19-Jul-2005 Revision 1.2 Summary and Features • • • • • High efficiency, low cost, low component count solution Ideally suited as a standby supply in a larger 48 V input system The DPA-Switch IC integrates − PWM controller and 220 V MOSFET switching device − Accurate 400 kHz trimmed internal oscillator − Accurate OV/UV protection − Hysteretic thermal shutdown − Overload, open loop and short-circuit protection − Cycle skipping for regulation at no-load without a minimum load Small footprint 1.85" × 1", low overall height 0.9", two-layer PCB 100% surface mount construction 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.comT. Power Integrations 5245 Hellyer Avenue, San Jose, CA 95138 USA. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 Table Of Contents 1 2 3 4 Introduction..................................................................................................................3 Power Supply Specification .........................................................................................4 Schematic ...................................................................................................................5 Circuit Description .......................................................................................................6 4.1 DPA-Switch Primary ............................................................................................6 4.2 Output Rectification .............................................................................................6 4.3 Output Feedback.................................................................................................7 5 PCB Layout .................................................................................................................7 6 Bill of Materials ............................................................................................................8 7 Transformer Specification ...........................................................................................9 7.1 Electrical Diagram ...............................................................................................9 7.2 Electrical Specifications.......................................................................................9 7.3 Materials..............................................................................................................9 7.4 Transformer Build Diagram ...............................................................................10 7.5 Transformer Construction..................................................................................10 8 Transformer Spreadsheets........................................................................................11 9 Performance Data .....................................................................................................13 9.1 Efficiency ...........................................................................................................13 9.2 Regulation .........................................................................................................14 9.2.1 Load...............................................................................................................14 9.2.2 Line ................................................................................................................14 9.3 Peak Power .......................................................................................................15 10 Waveforms ................................................................................................................15 10.1 Drain Voltage and Current, Full Load Operation ...............................................15 10.2 Output Voltage Start-Up Profile .........................................................................16 10.3 Drain Voltage and Current Start-Up Profile .......................................................16 10.4 Load Transient Response (75% to 100% Load Step) .......................................16 10.5 Output Ripple Measurements............................................................................18 10.5.1 Ripple Measurement Technique ....................................................................18 10.5.2 Output Ripple Measurements ........................................................................19 11 Thermal Performance................................................................................................20 12 Control Loop Measurements .....................................................................................22 12.1 36 VDC Maximum and Nominal Load ...............................................................22 12.2 57 VDC Maximum Load ....................................................................................23 13 Revision History ........................................................................................................24 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 isolated source to provide power to the prototype board. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 1 Introduction This document is an engineering report describing an isolated 3.3 V, 2 A (6.6 W) DC-DC converter utilizing a DPA423G. This design is intended as an evaluation platform for DPA-Switch devices in the 8-pin DIP, low cost surface-mount package. High operating efficiency, low parts count and small footprint make this circuit an ideal choice for standby supplies or other low power applications operating from telecom input voltages. This report contains the power supply specification, schematic, bill of materials, transformer documentation, printed circuit board layout, and performance data. Top Side Bottom Side Figure 1 - EP-71 Populated Circuit Board Photograph. Page 3 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 2 Power Supply Specification Description Symbol Min VIN 36 VOUT1 3.20 Output Ripple Voltage Continuous Output Current Peak Output Current VRIPPLE1 IOUT IOUT 0 2.0 Total Output Power Continuous Output Power Peak Output Power POUT POUT_PEAK Input Voltage Output Output Voltage η Efficiency 78 Typ Max Units Comment 72 VDC OV shutdown at 90 V typ. 3.30 3.40 V ±3% including setpoint, line/load regulation 35 50 2.0 mVpp A A 6.6 8.25 W W 79 % 2.5 20 MHz bandwidth Measured at 48 V, o POUT (6.6 W), 25 C Environmental Safety Isolation Ambient Temperature 1500 TAMB Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com 0 VDC 50 o C 1 min. Free convection, sea level Page 4 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 3 Schematic *All resistors and capacitors 0805 size unless specified otherwise Figure 2 - EP-71 Schematic. Page 5 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 4 Circuit Description The schematic in Figure 2 shows a DC input flyback converter using the DPA423G device operating at 400 kHz. The circuit is designed for the standard nominal 48 V telecom input voltage range of 36-72 VDC. Using the Flyback topology, circuit board size, parts count and cost are minimized, while attaining excellent operating efficiency across the input voltage range. 4.1 Input Filtering An input pi filter formed by C1, L1 and C2 reduces the input ripple current and high frequency noise. However additional external filtering may be required depending on applicable standards and specific application. 4.2 DPA-Switch Primary The DPA423G IC (U1) provides startup, PWM control, under-voltage lock out, overvoltage shutdown and over-temperature protection functions. The integrated 220 V MOSFET has excellent switching characteristics at the selected 400 kHz operating frequency. This together with the minimal power consumption of the control enables a typical operating efficiency of 75% to 80% across the operating input voltage range (see Figure 7). The DC input voltage is applied to the primary winding of T1. The other side of the transformer primary is driven by the integrated MOSFET in U1. Zener diode VR1 and C3 clamp leakage spikes generated when the MOSFET in U1 turns off. Under normal operation, VR1 does not conduct but limits the maximum drain voltage under input overvoltage and output overload conditions. Resistor R5 programs the typical input under-voltage on-threshold to 33 VDC and the protective overvoltage shutdown to 90 VDC. Resistors R4 and R6 program the internal device current limit to reduce with increasing input voltage. Maximum output (overload) current varies less than 5% across the operating voltage range. The reduction in overload output current reduces secondary transformer leakage spikes and allows the use of a 30 V Schottky diode for the output rectifier D1. The primary bias winding provides CONTROL pin current after start-up. Diode D2 rectifies the bias winding, while components R5 and C11 reduce the high frequency switching noise and reduce peak charging of the bias voltage. The DPA423G operates well within the recommended junction temperature limits (110 °C) at an elevated ambient of 50 °C, in a free-convection cooled environment (see Section 10). 4.3 Output Rectification Schottky output diode D1 enables low loss rectification of the secondary winding voltage. Low ESR tantalum output capacitors, C7 to C9, reduce switching ripple and minimize Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 6 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply losses. Secondary output choke L2 and ceramic output capacitor C10 reduce high frequency noise and ripple at the output. 4.4 Output Feedback The output voltage is sensed via the resistor divider formed by R9 and R10 and fed into the reference pin of the low voltage reference, U3. Feedback compensation components R7, R8, and C13 ensure stable operation and optimum line and load transient response. Capacitor C12 provides a soft-finish characteristic, preventing output voltage overshoot during startup of the converter. 5 PCB Layout Figure 3 - Top Side, SMT Printed Circuit Layout (Top View). Figure 4 - Bottom Side, SMT Printed Circuit Layout (Top View). Page 7 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 6 Bill of Materials Item Qty Reference Description P/N Manufacturer 1 2 1 1 U1 U2 DPA423G PC357N1TA Power Integrations Sharp 3 1 U3 CAT431L Catalyst Semiconductor 4 5 6 7 8 9 10 1 1 1 2 1 3 1 C1, C2 C3 C4 * C5, C13 C6 C7-9 C10 THCS50E2A155ZT ECJ-2VC2D470J 1808SC102KAT1A ECJ-2YB1H104K ECST1AC226R T495X337K006AS ECY-29RA105KV UCC Panasonic AVX Panasonic Panasonic Kemet Panasonic 11 12 13 14 15 1 1 1 1 4 ECJ-3FF1H105Z ECJ-2YB1C334K SL43 BAV21 4531051-0000 Panasonic Panasonic Vishay generic Zierick 16 17 18 19 20 21 22 23 24 25 26 27 28 1 1 1 1 1 1 1 1 1 1 1 1 1 C11 C12 D1 D2 J1-1,2 J2-1,2 L1 L2 R1 R2 R3 R4 * R5 R6 R7 R8 R9 R10 T1 DPA-Switch Optocoupler, 80-160% graded CTR Low voltage shunt regulator, SOT23 1.5 µF, 100 V, 1812 47 pF, 200 V 1000 pF, 1500 V, 1808 0.1 µF, 50 V 22 µF, 10 V, tantalum, C size 330 µF, 6.3 V, tantalum, X size 1 µF, 10 V, 0508 alternative geometry 1 µF, 50 V, 1206 0.33 µF, 50 V 30 V, 4 A Schottky 200 V, 200 mA Pin, surface mount, 0.040 x 0.375” 10 µH, 1 A 1 µH, 2 A 1.00 MΩ, 1% 619 kΩ, 1% 8.66 kΩ, 1% 10 Ω 100 Ω 5.1 Ω 75 Ω 1 kΩ 34.0 kΩ, 1% 20.0 kΩ, 1% ER14.5 Transformer 29 1 VR1 150 V TVS SCD-0403-100MT SCD-0403-1R0M ERJ-6ENF1004V ERJ-6ENF6193V ERJ-6ENF8661V ERJ-6GEYJ100V ERJ-6GEYJ101V ERJ-6GEYJ5R1V ERJ-6GEYJ750V ERJ-6GEYJ102V ERJ-6ENF3402V ERJ-6ENF2002V LSTA30825 SIL6029 IM 040 202 31 SMAJ150A Chilisin Chilisin Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic L.S.E. HiCal Vogt Generic Resistors and capacitors size 0805, unless specified otherwise. * Optional components C4 and R4 may be included for improved EMI performance. Recommended values are shown. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 8 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 7 Transformer Specification 7.1 Electrical Diagram ER14.5 3C96 / 3F3, 10 pin Bobbin 1 9,10 WDG #4 10T #34 AWG WDG #3 2T #28 AWG x2 2 6,7 4 WDG #1 10T #34 AWG WDG #2 8T #34 AWG 3 5 Figure 5 - Transformer Electrical Diagram. 7.2 Electrical Specifications Electrical Strength Primary Inductance Resonant Frequency Primary Leakage Inductance 7.3 1 second, 60 Hz, from pins 1-5 to pins 6-10 pins 1-3, all other windings open Pins 1-3, all other windings open Pins 1-3, with pins 6/7-9/10 shorted 1500 VDC 120 µH, +/-10% 7.5 MHz (Min.) 3.0 µH (Max.) Materials Item [1] [2] [3] [4] [5] [6] [7] Description Core: ER14.5, Ferroxcube 3C96, 3F3 (or equivalent), ALG = 312 nH/T2 Bobbin: ER14.5, 10 pin Magnet wire: #34 AWG, double coated (heavy nyleze) Magnet wire: #28 AWG, double coated (heavy nyleze) Tape: 3M 1298 polyester film (or equivalent), 1.8 mm wide Core clamp ER14.5 Ferroxcube CLM14.5 (optional) Varnish (DIPPED ONLY, NOT IMPREGNATED) Page 9 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 7.4 19-Jul-2005 Transformer Build Diagram Pin Side Tape 1 1/2 Primary Tape 6,7 Secondary 9,10 Tape 5 4 Bias 2 3 1/2 Primary Figure 6 - Transformer Build Diagram. 7.5 Transformer Construction Bobbin Preparation ½ Primary Bias Winding Basic Insulation Secondary Winding Basic Insulation ½ Primary Outer Insulation Final Assembly Arrange bobbin & rotation such that primary start/finish wires do not overlap. Start at pin 3. Wind 10 turns of item [3] in 1 layer. Bring finish lead back and terminate on pin 2. Starting at pin 4, wind 8 turns of item [3]. Spread turns evenly across bobbin in a single layer. Bring finish lead back and terminate on pin 5. Use one layer of item [5] for basic insulation. Start at pins 9 and 10. Wind 2 turns of bifilar item [4] in 1 layer. Bring finish lead back and terminate on pins 6 and 7. Use one layer of item [5] for basic insulation. Continue from pin 2. Wind 10 turns of item [3] in 1 layer. Bring finish lead back and terminate on pin 1. Use one layer of item [5] for basic insulation. Assemble and secure (glue or clamp, item [6]) core halves. Dip varnish item [7] and cure. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 10 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 8 Transformer Spreadsheets Page 11 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com 19-Jul-2005 Page 12 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 9 Performance Data All measurements were performed at room temperature utilizing a DC input source and DC dynamic loads. Input and output voltages and current were measured with dedicated DVMs. 9.1 Efficiency 82% 81% 80% Efficiency (%) 79% 78% 77% VIN = 36 VDC VIN = 48 VDC VIN = 57 VDC VIN = 75 VDC 76% 75% 74% 73% 72% 0.50 0.75 1.00 1.25 1.50 1.75 2.00 Load Current (A) Figure 7 - Efficiency vs. Output Load, Room Temperature. Page 13 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 9.2 19-Jul-2005 Regulation 9.2.1 Load Output Voltage (VDC) 3.40 3.35 VIN = 36 VDC VIN = 48 VDC VIN = 57 VDC VIN = 36 VDC VIN = 48 VDC VIN = 57 VDC VIN = 75 VDC 3.30 3.25 3.20 0.0 0.3 0.5 0.8 1.0 1.3 1.5 1.8 2.0 Load Current (A) Figure 8 - Load Regulation, Room Temperature. 9.2.2 Line Output Voltage (VDC) 3.40 3.35 Full Load (2 A) 50% Load (1 A) No Load 3.30 3.25 3.20 30 40 50 60 Input Voltage (VDC) Figure 9 - Line Regulation, Room Temperature. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 14 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 9.3 Peak Power The DC output load current was recorded just prior to the auto-restart operation. 3.00 Output Current (A) 2.90 2.80 2.70 2.60 2.50 30 40 50 60 70 80 Input Voltage (VDC) Figure 10 - Maximum Output Overload Current, Room Temperature. 10 Waveforms 10.1 Drain Voltage and Current, Full Load Operation Figure 11 – 36 VDC, Full Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 50 V, 1 µs / div. Page 15 of 28 Figure 12 – 57 VDC, Full Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 50 V, 1 µs / div. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 10.2 Output Voltage Start-Up Profile Figure 13 - Start-up Profile, 36 VDC, No Load (Worstcase). Upper: VOUT, 1 V / div. Lower: VDRAIN, 50 V, 10 ms / div. Figure 14 - Start-up Profile, 57 VDC, No Load (Worst-case). Upper: VOUT, 1 V / div. Lower: VDRAIN, 50 V, 10 ms / div. 10.3 Drain Voltage and Current Start-Up Profile Figure 15 – 36 VDC Input, 2 A Resistive Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 100 V, 10 ms / div. Figure 16 – 57 VDC Input, 2 A Resistive Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 100 V, 10 ms / div. 10.4 Load Transient Response (75% to 100% Load Step) In the following two oscilloscope screen shots (Figure 17 and 18), signal averaging was used to more clearly capture the output voltage response to a load transient. Averaging minimizes the appearance of the 400 kHz switching ripple in the output voltage scope plot. The load current step was used to trigger the horizontal sweep of the oscilloscope. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 16 of 28 19-Jul-2005 Figure 17 - Transient Response, 36 VDC, 75-100-75% Load Step. Upper: Load Current, 1 A / div. Lower: Output Voltage, 20 mV, 500 µs / div. Page 17 of 28 EP-71 3.3 V, 2 A DC-DC Power Supply Figure 18 - Transient Response, 57 VDC, 75-100-75% Load Step. Upper: Load Current, 1 A / div. Lower: Output Voltage, 20 mV, 500 µs / div. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 10.5 Output Ripple Measurements 10.5.1 Ripple Measurement Technique For DC output ripple measurements, a modified oscilloscope test probe must be utilized in order to reduce spurious signals due to pickup. Details of the probe modification are provided in Figures 19 and 20. The 5125BA probe adapter is affixed with two capacitors tied in parallel across the probe tip. The capacitors include one (1) 0.1 µF/50 V ceramic type and one (1) 1.0 µF/50 V aluminum electrolytic. The aluminum electrolytic type capacitor is polarized, so proper polarity across DC outputs must be maintained (see below). Probe Ground Probe Tip Figure 19 - Oscilloscope Probe Prepared for Ripple Measurement (End Cap and Ground Lead Removed). Figure 20 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter (Modified with Wires for Probe Ground for Ripple Measurement, and Two Parallel Decoupling Capacitors Added). Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 18 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 10.5.2 Output Ripple Measurements Figure 21 - Ripple, 36 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Figure 22 - Ripple, 48 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Figure 23 - Ripple, 57 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Figure 24 – Ripple, 75 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Page 19 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 11 Thermal Performance The temperatures of key components were recorded using T-type thermocouples. Two of the four thermocouples were soldered, one directly to a SOURCE pin of the DPA423G (U1) and the other to the cathode of the output rectifier (D1). The other two thermocouples were glued, one to the transformer (T1) core on the center leg, and the other to the case of the first of the two high-ripple output capacitors (C7). The unit was operated at full load, at 36 VDC, 48 VDC and 57 VDC in free convection within a small enclosure to prevent external air currents affecting the measurements. The results show adequate thermal margin, considering an additional ambient rise of +29 °C. At 36 VDC, full load, within an enclosure at elevated 50 °C ambient, this equates to a DPA423G case temperature of 79 °C. This is well below the recommended maximum case temperature of 100 °C. An infrared measurement taken at nominal-line (48 VDC) is provided. Measured Temperature (°C) Item 36 VDC 48 VDC 57 VDC Ambient 21 21 21 DPA423G (U1) 50 49 49 Transformer core (T1) 75 74 74 Output Rectifier (D1) 66 64 64 Output Capacitor (C7) 42 41 42 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 20 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply TOP VIEW BOTTOM VIEW Figure 25- Infrared Thermograph of Top of EP-71 Board, 48 VDC, Full Load, Room Ambient. Page 21 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 12 Control Loop Measurements 12.1 36 VDC Maximum and Nominal Load Figure 26 - Gain-Phase Plot, 36 VDC, Maximum Load (2 A). Vertical Scale: Gain = 10 dB / div, Phase = 30° / div. Crossover Frequency = 10.0 kHz, Phase Margin = 60° Figure 27 - Gain-Phase Plot, 36 VDC, Light Load (100 mA). Vertical Scale: Gain = 10 dB / div, Phase = 30° / div. Crossover Frequency = 0.9 kHz, Phase Margin = 65° Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 22 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply 12.2 57 VDC Maximum Load Figure 28 - Gain-Phase Plot, 57 VDC, Light Load (100 mA). Vertical Scale: Gain = 10 dB / div, Phase = 30° / div. Crossover Frequency = 10.8 kHz, Phase Margin = 40° Figure 29 - Gain-Phase Plot, 57 VDC, Light Load (100 mA). Vertical Scale: Gain = 10 dB / div, Phase = 30° / div. Crossover Frequency = 0.9 kHz, Phase Margin = 60° The results indicate adequate loop bandwidth and significant gain and phase margin. Page 23 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 13 Revision History Date 11-Mar-04 16-Mar-04 22-Mar-04 02-Apr-04 19-Jul-05 Author SH PV PV KM PV Revision 0.1 0.2 1.0 1.1 1.2 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Description & changes First draft Minor text edits Insert board photograph Added vendor name to Bill of Materials Fixed schematic and bill of materials (BOM) Page 24 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply Notes Page 25 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 Notes Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 26 of 28 19-Jul-2005 EP-71 3.3 V, 2 A DC-DC Power Supply Notes Page 27 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-71 3.3 V, 2 A DC-DC Power Supply 19-Jul-2005 For the latest updates, visit our website: www.powerint.com Power Integrations 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 Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com. Power Integrations grants its customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm. The PI Logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, EcoSmart, PI Expert and PI FACTS are trademarks of Power Integrations, Inc. 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