Engineering Prototype Report for EP-86 – 6.6 W Multi-Class Powered Device (PD) for Power over Ethernet (PoE) Using DPA-Switch® (DPA423G) Title Specification Input: 33-57 VDC, Output: 3.3 V / 2.0 A Application PoE Class 2 PD – Including IEEE802.3af Compliant Interface Circuit Author Power Integrations Applications Department Document Number EPR-86 Date April 13, 2006 Revision 1.1 Summary and Features • • • Meets IEEE802.3af requirements according to University of New Hampshire Interoperability Consortium (UNH-IOC) test results, for Class 1–3 PoE PDs DPA-Switch PWM controller with integrated 220 V power MOSFET switch • Under-voltage (UV) and overvoltage (OV) shutdown functions • Auto-recovering, hysteretic thermal shutdown • Auto-restart function: protects against short-circuit and open loop faults • No-load regulation achieved by cycle skipping • Fully integrated soft-start minimizes start-up stress and overshoot • Externally programmed ILIMIT scales with VIN for power limiting • Lossless MOSFET current sense eliminates external sensing components Small footprint 3.1" × 1", low overall height 0.45" (excluding RJ-45 connector) 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 5245 Hellyer Avenue, San Jose, CA 95138 USA. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 Table Of Contents 1 2 3 4 Introduction.................................................................................................................3 Power Supply Specification ........................................................................................4 Schematic...................................................................................................................5 Circuit Operation.........................................................................................................6 4.1 General ................................................................................................................6 4.2 DPA-Switch Primary.............................................................................................6 4.3 Output Rectification ..............................................................................................6 4.4 Output Feedback..................................................................................................6 4.5 PoE Interface Circuit Description..........................................................................7 4.6 Wide Hysteresis Under-Voltage Lockout..............................................................8 5 Bill of Materials .........................................................................................................10 6 Layout.......................................................................................................................12 7 Transformer Design Spreadsheet.............................................................................13 8 Transformer Specification.........................................................................................15 8.1 Transformer Winding..........................................................................................15 8.2 Electrical Specifications......................................................................................15 8.3 Materials.............................................................................................................15 8.4 Transformer Build Diagram ................................................................................16 8.5 Transformer Construction...................................................................................16 9 Performance Data ....................................................................................................17 9.1 Efficiency............................................................................................................17 9.2 Load Regulation .................................................................................................18 9.3 Line Regulation ..................................................................................................18 9.4 Overload Output Current ....................................................................................19 10 Waveforms............................................................................................................20 10.1 Drain Voltage and Current, Full-Load Operation ................................................20 10.2 Output Voltage Start-Up Profile ..........................................................................20 10.3 Load Transient Response (75% to 100% Load Step) ........................................21 10.4 Output Ripple Measurements.............................................................................22 10.4.1 Ripple Measurement Technique ................................................................22 10.4.2 Output Ripple Measurements.....................................................................23 11 Revision History ....................................................................................................24 Important Note: Although this board was designed to satisfy safety isolation requirements, it has not been agency approved. Therefore, please take the appropriate safety precautions. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 1 Introduction This engineering report describes a PoE power supply designed around the DPA423G. The supply can deliver 6.6 W continuously, from an input voltage range of 33 VDC to 57 VDC. The following design information is provided: the power supply specification, circuit diagrams, a complete bill of materials, the results of the PIXls spreadsheet file that was used to design the supply and detailed information on the design and construction of the transformer. Data and test results that document the performance of the supply under various line and load conditions are also included. Figure 1 – Populated Circuit Board Top View. Figure 2 – Populated Circuit Board Bottom View. Page 3 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 2 Power Supply Specification Description Input Voltage Under-Voltage ON Under-Voltage OFF Output Output Voltage 1 Output Ripple Voltage 1 Output Current 1 Output Peak Current 1 Total Output Power Average Output Power Average Output Power Full Load Efficiency Symbol Min Typ Max Units VIN VIN_UV_ON VIN_UV_OFF 33 48 57 42 VDC VDC VDC 3.3 3.465 35 2 V mVp-p A A VOUT1 VRIPPLE1 IOUT1 IOUT1_PK 33 3.135 0 2.5 6.6 POUT1 POUT_FAULT η W W % 8.6 73 Comment ± 5% 20 MHz bandwidth R6 = 10.2 Ω Environmental Conducted EMI Meets CISPR22B / EN55022B Designed to meet IEC950, UL1950 Class II Safety Ambient Temperature TAMB 0 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com 40 o C Page 4 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 3 Schematic Figure 3 – Schematic. Page 5 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 4 Circuit Operation 4.1 General A flyback topology was used to minimize circuit board size, parts count and cost. This topology also provides excellent operating efficiency across the input voltage range. 4.2 DPA-Switch Primary The DPA423G IC implements PWM control of the internal power MOSFET and initiates a soft start-up function when it first powers up. The IC also monitors die temperature as part of its over-temperature protection function and also monitors the input voltage as part of its under-voltage detection and overvoltage shutdown functions. The integrated 220 V MOSFET provides excellent switching characteristics at the selected 400 kHz operating frequency. The MOSFET and controller consume very little power, giving good efficiency across the entire input voltage operating range. Diodes D3 through D9 ensure that the incoming DC input voltage is correctly polarized. Capacitors C1 and C2 and inductor L1 form a low-cost pi (π) filter that attenuates conducted EMI noise, to keep it from being passed to the incoming line. Resistors R4 and R6 program the internal current limit of the DPA423G, so that it reduces as the input voltage increases. This helps to keep the variance of the maximum output overload current below 5%, across the entire input voltage range. The IC’s integrated MOSFET is protected from overvoltage stresses that could damage it (during a line surge) by a primary-side Zener diode clamp (VR3). Zener diode VR3 does not conduct under normal operating conditions. The primary bias winding provides CONTROL pin current after start-up. Diode D2 rectifies the bias winding voltage, while R8 and C11 attenuate high frequency switching noise and reduce the peak charging of the bias voltage. 4.3 Output Rectification The secondary winding voltage is rectified by a low-loss Schottky diode (D11). Low ESR, tantalum output capacitors, C7 and C8, filter the output voltage. The LC output filter (L2, C9 and C10) further attenuates switching noise and ripple from the output voltage. 4.4 Output Feedback Resistor divider (R12 and R13) senses the output voltage and feeds it into the reference pin of a 1.24 V reference IC (U4). The conduction of U4 pulls current through the LED of optocoupler U5, which controls the conduction of its phototransistor (U5-B). The phototransistor modulates the current that flows into the CONTROL pin of U1. Since the DPA-Switch is a current-to-duty-cycle converter, it uses the varying CONTROL pin current to pulse-width modulate the duty cycle of the MOSFET switch. Resistor R10 sets the gain of U4, while R11 and C13 compensate for the variation in gain of U4 over the frequency range of the feedback loop’s bandwidth (about 10 kHz). Feedback Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 6 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device compensation is required to ensure stable operation of the supply and optimum response to line and load transients. Capacitor C12 performs a soft-finish function that prevents the output voltage from overshooting the regulation set point during initial startup of the converter. 4.5 PoE Interface Circuit Description See DI-88 for a full description. Resistor R26 provides the correct impedance for the detection phase of PD operation. Figure 4 – Detection Impedance V-I curve. The classification circuit is enabled when Zener diode VR6 conducts (above 11 VDC). Transistor Q9 controls the bias current source programmed to approximately 350 µA by resistor R21. This bias current source provides the minimum operating current to voltage reference IC U6. The main classification current flowing through R20 generates a voltage that is referenced to the internal reference (1.24 VDC) of U6 and that later closes the loop by controlling the base drive of Q7. The value of the classification current source is determined by the value of the voltage on the reference pin of U6 divided by the value of R20 in ohms. Page 7 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 Figure 5 – Table of PoE Classifications and Power Levels. Figure 6 – Classification Current (Class 2: R34 = 69.8 Ω; Class 3: R34 = 45.3 Ω). Zener diode VR5 conducts above 27 VDC, raising the gate voltage on the pass-switch MOSFET (Q8), turning it on when the gate-threshold voltage is exceeded. Pull-down resistor R25 limits the current through VR5 while pull-down resistor R24 keeps Q8 turned off, unless it is being actively driven on. Zener diode VR4 limits the maximum gate-tosource voltage on Q8 to 15 V. When VR5 conducts, it also turns on Q6 through R23. Transistor Q6 pulls down on the base of Q7, which turns off the main classification current source (although the bias current source of 350 µA will continue to conduct). 4.6 Wide Hysteresis Under-Voltage Lockout If there were no other components connected to the L pin, then resistor R5 would set the under-voltage turn-on threshold to approximately 35 VDC and the turn-off threshold to approximately 33 VDC. However, in the case of PoE, the turn-on voltage is much higher than the turn-off voltage. This requires more under-voltage hysteresis. When the power supply is operating normally, the bias voltage is approximately 14 VDC. Resistors R15 and R16 form a voltage divider that turns off the base of Q2, once the DC-DC converter has begun switching and the bias voltage is present. At start-up, when the bias voltage is absent, Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 8 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device Q2 is on, and sinks additional current from the resistor (R5) that connects the L pin to the DC input voltage. The value of R14 was selected so that an extra 10 µA is drawn at startup, which increases the turn-on threshold voltage to 41 VDC typical. However, because Q2 turns off after start-up, the UV turn-off threshold stays at 34 VDC (see DI101 for more details). Figure 7 – L-pin current without and with the widened UV hysteresis circuit. Page 9 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 5 Bill of Materials Item Qty. Ref. Description Mfg Part Number Mfg 1 2 C1, C2 470 nF, 100 V, Ceramic, X7R, 1210 ECJ-4YB2A474K Panasonic 2 1 C3 47 pF, 100 V, Ceramic, NPO, 0603 06031A470JAT2A AVX 3 1 C4 1000 pF, 1500V, 1808 1808SC102KAT1A AVX 4 2 ECJ-1VB1E104K Panasonic 5 1 TAJA226K010R Kemet 6 3 Kemet 7 1 C10 1 µF, 16 V, Ceramic, X5R, 0603 T495X337K006AS GRM188R61C105KA 93D Murata 8 1 C11 1 µF, 25 V, Ceramic, X7R, 1206 ECJ-3YB1E105K Panasonic 9 1 C12 06033D224KAT2A AVX 10 1 220 nF, 25 V, Ceramic, X7R, 0603 75 V, 0.2 A, Fast Switching, 50 ns, SOD323 1N4148WS-7 Diode Inc. 11 8 DL4002 Diodes Inc 12 1 D11 SL42-9B Vishay 13 1 J1 RJHS-5080 Amphenol Canada 14 2 15 1 L1 16 1 L2 17 1 18 3 19 1 20 1 Q8 100 V, 1.15 A, 250 mΩ, N-Channel, SOT-23 21 1 R4 22 1 23 C5, C13 100 nF 25 V, Ceramic, X7R, 0603 C6 22 µF, 10 V, Tant Electrolytic, SMD C7, C8, C9 330 µF, 6.3 V, Tant Electrolytic, SMD D2 D3, D4, D5, D6, D7, D8, 100 V, 1 A, Rectifier, Glass Passivated, DOD9, D10 213AA (MELF) 20 V, 4 A, Schottky, SMD, DO-214AB R/A, RJ45 Non-shielded, PCBM J2-1, J2-2 Zierick output pins 10 µH, 0.85 A Zierick HM79-10100LFTR7 B.I.Technologies HM79-101R0LFTR7 B.I.Technologies MMST3906-7 Diodes Inc MMBTA06LT1 On Semiconductor MMST3904 Diodes Inc SI2328DS Vishay 1.00 MΩ, 1%, 1/16 W, Metal Film, 0603 ERJ-3EKF1004V Panasonic R5 649 kΩ, 1%, 1/8 W, Metal Film, 0805 ERJ-6ENF6493V Panasonic 1 R6 10.00 kΩ, 1%, 1/16 W, Metal Film, 0603 ERJ-3EKF1002V Panasonic 24 1 R7 10 Ω, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ100V Panasonic 25 1 R8 100 Ω, 1%, 1/16 W, Metal Film, 0603 ERJ-3EKF1000V Panasonic 26 1 R9 5.1 Ω, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ5R1V Panasonic 27 1 R10 75 Ω, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ750V Panasonic 28 1 R11 1 kΩ, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ102V Panasonic 29 1 R12 33.2 kΩ, 1%, 1/8 W, Metal Film, 0805 ERJ-6ENF3322V Panasonic 1 µH, 1.9 A PNP, Small Signal BJT, 40 V, 0.2 A, SOTQ2 323 Q4, Q5, NPN, Small Signal BJT, 80 V, 0.5 A, SOTQ7 23 NPN, Small Signal BJT, 40 V, 0.2 A, SOTQ6 323 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 10 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 30 1 R13 20 kΩ, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ203V Panasonic 31 1 R14 174 kΩ, 1%, 1/16 W, Metal Film, 0603 ERJ-3EKF1743V Panasonic 32 1 ERJ-3GEYJ103V Panasonic 35 1 R20 69.8 Ω, 1%, 1/16 W, Metal Film, 0603 ERJ-3EKF69R8V Panasonic 36 1 R21 2 kΩ, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ202V Panasonic 37 2 ERJ-3GEYJ104V Panasonic 38 1 R24 220 kΩ, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ224V Panasonic 39 1 R25 51 kΩ, 5%, 1/10 W, Metal Film, 0603 ERJ-3GEYJ513V Panasonic 40 1 R26 24.9 kΩ, 1%, 1/8 W, Metal Film, 0805 41 1 T1 Bobbin, ER14.5/6, Horizontal, 10 pins, SMD ERJ-6ENF2492V HM00-A5861LF DA2062-ALD SIL6029 LSTA30825 SNX1393 YC-1404S Panasonic B.I Technologies Coilcraft Hical LiShin Santronics Ying Chin 42 1 U1 DPA423G 43 1 U4 Power Integrations National Semiconductor 44 1 U5 45 1 U6 DPA-Switch, DPA423G, SMD-8 1.24 V Shunt Regulator IC, 1%, -40 to 85 °C, SOT23-5 Optocoupler, 80 V, CTR 200-400%, 4-Mini Flat 1.24 V Shunt Regulator IC, 1%, -40 to 85 °C, SOT23-5 46 1 VR3 150 V, 5 W, 5%, DO214AC (SMB) 47 1 VR4 48 1 49 50 R15, R16 10 kΩ, 5%, 1/10 W, Metal Film, 0603 R22, R23 100 kΩ, 5%, 1/10 W, Metal Film, 0603 LMV431AIM5 LMV431AIM5 Sharp National Semiconductor SMBJ150A Diodes, Inc 15.0 V, 5%, 150 mW, SOD-323 BZT52C15T-7 Diodes, Inc VR5 27.0 V, 5%, 150 mW, SOD-323 MAZS2700ML Panasonic-SSG 1 VR6 11 V, 5%, 500 mW, DO-213AA (MELF) ZMM5241B-7 Diodes Inc 1 - Page 11 of 28 PC357N3T PCB, EP-86, REV B Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 6 Layout Figure 8 – PCB Layout Top Side. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Figure 9 – PCB Layout Bottom Side. Page 12 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 7 Transformer Design Spreadsheet DCDC_DPASwitch_Flyback_071405; Rev.2.7; Copyright Power Integrations 2005 INPUT INFO OUTPUT UNITS ENTER APPLICATION VARIABLES VDCMIN VDCMAX VO 36 57 3.3 Volts Volts Volts PO n Z 6.6 Comment 0.8 Watts VB 14 0.7 DPASwitch_Flyback_071405 - Continuous/Discontinuous mode Spreadsheet. Copyright 2005 Power Integrations DC-DC Converter Minimum DC Input Voltage Maximum DC Input Voltage Output Voltage (main) Verify temperature rise for continuous power. P and G packages may be thermally limited Efficiency Estimate Loss Allocation Factor, (0.7 Recommended) Volts Bias Voltage (Recommended between 12V and 18V) Volts Volts Volts Volts k-Ohms Minimum undervoltage On-Off threshold Maximum undervoltage Off-On threshold (turn-on) Minimum overvoltage Off-On threshold Maximum overvoltage On-Off threshold (turn-off) UV AND OV PARAMETERS min VUVOFF VUVON VOVON VOVOFF RL 30.0 32.2 74.9 max 33.1 34.7 94.7 619.0 ENTER DPASWITCH VARIABLES DPASWITCH Chosen Device ILIMITMAX Frequency fS VOR KI ILIMITEXT RX VDS VD VDB KRP/KDP DPA423G DPA423G 1.16 F 375000 38 0.7 16VDC Power Ou 6W 1.34 Amps Hertz 38 Volts 0.7 0.812 Amps 11.0 k-Ohms Volts Volts Volts 1 0.5 0.7 0.62 36 VDC 13W From DPASWITCH Data Sheet Enter 'F' for fS = 400KHz and 'L' for fS = 300KHz DPASWITCH Switching Frequency Reflected Output Voltage Current Limit Reduction Factor Minimum External Current limit Resistor from X pin to source to set external current limit DPASWITCH on-state Drain to Source Voltage Output Winding Diode Forward Voltage Drop Bias Winding Diode Forward Voltage Drop Ripple to Peak Current Ratio (0.2 < KRP < 1.0 : 1.0< KDP<6.0) ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES Core Type Core Manuf Bobbin Manuf Core Bobbin AE LE AL BW M L NS Page 13 of 28 ER14.5 ER14.5 ER14.5_Bobbin 0.176 1.9 1400 1.9 0 2 2 P/N: P/N: cm^2 cm nH/T^2 mm mm ER14.5-3F3-S CPVS-ER14.5-1S-10P Core Effective Cross Sectional Area Core Effective Path Length Ungapped Core Effective Inductance Bobbin Physical Winding Width Safety Margin Width (Half the Primary to Secondary Creepage Distance) Number of Primary Layers Number of Secondary Turns Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 CURRENT WAVEFORM SHAPE PARAMETERS DMAX IAVG IP IR IRMS 0.52 0.23 0.64 0.40 0.33 Amps Amps Amps Amps Maximum Duty Cycle Average Primary Current Peak Primary Current Primary Ripple Current Primary RMS Current TRANSFORMER PRIMARY DESIGN PARAMETERS LP NP NB ALG 119 uHenries Primary Inductance 20 Primary Winding Number of Turns 8 Bias Winding Number of Turns 297 nH/T^2 Gapped Core Effective Inductance Peak Flux density during transients (Limit to 3000 Gauss) 2739 Gauss Maximum Flux Density 2152 Gauss AC Flux Density for Core Loss Curves (0.5 X Peak to Peak) 667 Gauss 1203 Relative Permeability of Ungapped Core Gap Length (Lg >> 0.051 mm) 0.06 mm 3.8 mm Effective Bobbin Width BP BM BAC ur LG BWE TRANSFORMER SECONDARY DESIGN PARAMETERS ISP ISRMS IO IRIPPLE 6.38 3.15 2.00 2.43 Amps Amps Amps Amps Peak Secondary Current Secondary RMS Current Power Supply Output Current Output Capacitor RMS Ripple Current VOLTAGE STRESS PARAMETERS VDRAIN PIVS PIVB 157 Volts 9 Volts 36 Volts Maximum Drain Voltage (Includes Effect of Leakage Inductance) Output Rectifier Maximum Peak Inverse Voltage Bias Rectifier Maximum Peak Inverse Voltage ADDITIONAL OUTPUTS V_OUT2 VD_OUT2 N_OUT2 PIV_OUT2 V_OUT3 VD_OUT3 N_OUT3 PIV_OUT3 Volts Volts 0.00 0 Volts Volts Volts 0.00 0 Volts Amps Amps I_OUT2 I_OUT3 N/A Negative Output Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com 2nd Output Voltage 2nd Output - Diode Forward voltage 2nd Output - Turns 2nd Output - Diode Peak Inverse Voltage 3rd Output Voltage 3rd Output - Diode Forward voltage 3rd Output - Turns 3rd Output - Diode Peak Inverse Voltage 2nd Output - Output Current 3rd Output - Output Current If negative output exists enter Output number; eg: If VO2 is negative output, enter 2 Page 14 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 8 Transformer Specification 8.1 Transformer Winding 1 2 3 4 5 W4: 10T 1 x 34 AWG W1: 10T 1 x 34 AWG W2: 8T 1 x 34 AWG 9,10 W3: 2 T 2 x 28 AWG 6,7 Figure 10 – Transformer Electrical Diagram. 8.2 Electrical Specifications Electrical Strength Primary Inductance Resonant Frequency Primary Leakage Inductance 8.3 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] (optional) [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 Varnish (DIPPED ONLY, NOT VACUUM IMPREGNATED) Page 15 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 8.4 13-Apr-2006 Transformer Build Diagram Tape Tape 1 W4 2 Tape 6,7 W3 9,10 Tape W2 5 4 Tape 2 3 W1 Figure 11 – Transformer Build Diagram. 8.5 Transformer Construction Bobbin Preparation W1 W2 Tape W3 Tape W4 Outer Wrap 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 16 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 9 Performance Data All measurements were taken at room temperature utilizing a DC input source and DC dynamic loads (except where resistive loads are specified). Input and output voltages and current were measured with dedicated digital multi-meters (DMMs). 9.1 Efficiency 80% Efficiency (% 70% 60% 36 VDC 48 VDC 57 VDC 50% 40% 0 2 4 6 8 Pout (W) Figure 12 – Efficiency vs. Line and Load, Room Temperature. Page 17 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 9.2 13-Apr-2006 Load Regulation 105.0% Regulation (%) 102.5% 100.0% 3V3 36 VDC 3V3 57 VAC 97.5% 95.0% 0 2 4 6 8 Pout (W) Figure 13 – Load Regulation, Room Temperature. Line Regulation 105.0% 102.5% Regulation (%) 9.3 100.0% 3.3V FL 3.3V LL 97.5% 95.0% 30 40 50 60 Vin (VDC) Figure 14 – Line Regulation, Room Temperature. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 18 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 9.4 Overload Output Current The DC output load current was recorded just prior to the auto-restart operation at various input line voltages. Performance was measured for various values of resistor R6. Output Current (A) 4.0 3.0 2.0 3.3 V R6 = 10.0 kΩ 3.3 V R6 = 10.2 kΩ 1.0 3.3 V R6 = 10.5 kΩ 3.3 V R6 = 8.66 kΩ 0.0 30 40 50 60 Vin (VDC) Figure 15 – Overload Output Current vs. Line Voltage for Different Values of R6, Room Temperature. Page 19 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 10 Waveforms 10.1 Drain Voltage and Current, Full-Load Operation Figure 16 – 36 VDC, Full Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 50 V, 1 µs / div. Figure 17 – 57 VDC, Full Load. Upper: IDRAIN, 0.5 A / div. Lower: VDRAIN, 50 V, 1 µs / div. 10.2 Output Voltage Start-Up Profile Figure 18 – Start-Up Profile, 36 VDC, No Load (worst-case). Upper: VOUT, 1 V / div. Lower: VDRAIN, 50 V, 1 µs / div. Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Figure 19 – Start-Up Profile, 57 VDC, No Load (worst-case). Upper: VOUT, 1 V / div. Lower: VDRAIN, 50 V, 1 µs / div. Page 20 of 28 13-Apr-2006 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 10.3 Load Transient Response (75% to 100% Load Step) In the figures shown below, signal averaging was used to better enable viewing of the load transient response. The oscilloscope was triggered using the load current step as a trigger source. Since the output switching is random with respect to the load transient, contributions to the output ripple from these sources will average out, leaving the contribution only from the load step response. Figure 20 – Transient Response, 36 VDC, 75-100-75% Load Step. Upper: Load Current, 1 A / div. Lower: Output Voltage, 20 mV, 500 µs / div. Page 21 of 28 Figure 21 – 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-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 10.4 Output Ripple Measurements 10.4.1 Ripple Measurement Technique For DC output ripple measurements, a modified oscilloscope test probe must be utilized in order to reduce spurious signal pickup. Details of the probe modification are provided in Figures 22 and 23. 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. Since the aluminum electrolytic type capacitor is polarized, proper polarity must be observed when connecting it to the output (see below). Probe Ground Probe Tip Figure 22 – Oscilloscope Probe Prepared for Ripple Measurement (End cap and ground lead removed). Figure 23 – 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, Inc. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 22 of 28 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 10.4.2 Output Ripple Measurements Figure 24 – Ripple, 36 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Figure 25 – Ripple, 48 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Figure 26 – Ripple, 57 VDC, Full Load. Upper: 50 µs / div, 10 mV / div. Lower: 2 µs / div, 10 mV / div. Page 23 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 11 Revision History Date January 3, 2006 April 13 2006 Author RM/LN/ME RM Revision 1.0 1.1 Power Integrations, Inc. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Description & changes Initial release Updated photo, layout, schematic and BOM Page 24 of 28 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 Notes Page 25 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 Notes Power Integrations, Inc. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 26 of 28 EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 Notes Page 27 of 28 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device 13-Apr-2006 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, PeakSwitch, EcoSmart, Clampless, E-Shield, Filterfuse, PI Expert and PI FACTS are trademarks of Power Integrations, Inc. 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