TND331/D Rev. 0, FEB - 2008 200 W Game Console AC-DC Adapter Reference Design Documentation Package © Semiconductor Components Industries, LLC, 2008 February, 2008 - Rev. 0 1 Publication Order Number: TND331/D Disclaimer: ON Semiconductor is providing this reference design documentation package “AS IS” and the recipient assumes all risk associated with the use and/or commercialization of this design package. No licenses to ON Semiconductor's or any third party's Intellectual Property is conveyed by the transfer of this documentation. This reference design documentation package is provided only to assist the customers in evaluation and feasibility assessment of the reference design. It is expected that users may make further refinements to meet specific performance goals. http://onsemi.com 2 TND331 TND331 200 W Game Console AC-DC Adapter Reference Design Documentation Package http://onsemi.com TECHNICAL NOTE OVERVIEW This reference document describes a built-and-tested, GreenPointt solution for a Game Console AC-DC adapter. The reference design is targeted for the XBOXE Game Console from Microsoft®. The block diagram of the architecture used in this reference design is shown in Figure1. As seen in the figure, this reference design employs an Active Clamp Forward topology for the main converter. A new, highly integrated active clamp controller IC from ONSemiconductor - NCP1562 - was used for this main converter. This eased the implementation due to the many features that are integrated, thereby reducing the overall system cost and number of components while achieving the higher efficiency targeted for this reference design. This reference design also includes a 5 V standby rail. This was implemented using the NCP1014 from ONSemiconductor. The NCP1014 is a switching regulator with an integrated high-voltage switch. This IC enabled the reference design to achieve a standby power consumption that easily met the Energy Star and California Energy Commission (CEC) requirements cost effectively. This reference design was targeted for the US model of the XBOX Game Console. As a result, in order to keep the cost on parity to commercially available models, this reference design does not include a PFC section and is designed for the 110 Vac input. In order to meet the requirements in other regions, this design can be modified to include a PFC section as well. Finally, though this reference design was targeted for the XBOXE Game Console, it can be easily adapted to fit the needs of other end applications. Since the main converter topology used for the reference design was the Active Clamp forward topology, the design can be modified to deliver much higher power requirements. A good example of a higher power design is available from ONSemiconductor's web site - a 305 W Desktop Power Supply (ATX) reference design using this same active clamp forward topology (Document Reference: TND313/D). Other applications such as game consoles with different output power requirements and other high power adapters are good candidates for adapting this reference design to meet specific requirements. Game Console AC-DC Adapter Figure 1. Reference Design Architecture Block Diagram http://onsemi.com 3 TND331 Introduction Energy Star and CEC programs for external power supplies are shown in Table 1 to Table 4. It should be noted that the Energy Star specifications are designed with the US market in mind. However, through its extensive partnership programs, several other countries and regions are implementing the Energy Star guidelines with very little changes. Due to the ever increasing feature sets that are being integrated into game consoles and other consumer electronic devices, the power requirements for these devices is also increasing along with them. At the same time, numerous regulatory and market forces are driving the need for higher efficiencies from the power supplies of these devices. The active mode and standby mode efficiency targets of the Table 1. Energy Star Energy Efficiency targets for Active Mode Nameplate Output Power (Pno) Minimum Average Efficiency in Active Mode (expressed as decimal) 0 to < 1 Watt ≥ 0.49 * Pno >1 and ≤49 Watts ≥ [0.09 * Ln(Pno)] + 0.49 > 49 Watts ≥ 0.84 Table 2. Energy Star No-load Energy Consumption Criteria Nameplate Output Power (Pno) Minimum Average Efficiency in Active Mode (expressed as decimal) 0 to <10 Watts ≤ 0.5 Watt ≥10 to ≤ 250 Watts ≤ 0.75 Watt Table 3. CEC Requirements - Effective January 1, 2007 Nameplate Output Minimum Efficiency in Active Mode 0 to < 1 Watt 0.49 * Nameplate Output >1 and ≤49 Watts [0.09 * Ln (Note 1) (Nameplate Output)] + 0.49 > 49 Watts 0.84 Maximum Energy Consumption in No-Load Mode 0 to <10 Watts 0.5 Watt ≥10 to ≤ 250 Watts 0.75 Watt Where Ln (Nameplate Output) = Natural Logarithm of the nameplate output expressed in Watts Table 4. CEC Requirements - Effective July 1, 2008 Nameplate Output Minimum Efficiency in Active Mode 0 to < 1 Watt 0.5 * Nameplate Output >1 and ≤51 Watts [0.09 * Ln (Note 1) (Nameplate Output)] + 0.5 > 51 Watts 0.85 Maximum Energy Consumption in No-Load Mode Any output 0.5 Watt Where Ln (Nameplate Output) = Natural Logarithm of the nameplate output expressed in Watts This reference design provides a solution to address the above challenges while meeting the aggressive specifications listed in the following section in a cost-effective manner. 1. “Ln” refers to the natural logarithm. The algabraic order of operations requires that the natural logarithm calculation be performed first and then multiplied by 0.09, with the resulting output added to 0.49. An efficiency of 0.84 in decimal form corresponds to the more familiar value of 84% when expressed as a percentage. http://onsemi.com 4 TND331 Specifications The target specifications for the reference design for several key parameters are outlined in this section. Efficiency • Active Mode Efficiency: The power supply efficiency Input • The Input Voltage range is 90 - 132 Vac, 47-63 Hz. • Maximum steady state input current to be less than 5A rms at 90 VAC for full load output. • Output • The output voltages for the power supply are 12 V and • • • • • +5 V standby. The accuracy of the output voltage must be ±5% or better at the load end of the connectors under all line and load conditions. The output ripple voltage of the power supply must not exceed 100 mVpp for 12 V output and 50 mVpp for +5V STBY output. The reference design should be capable of supplying 203W total output power under all specified conditions. The 12 V output should be capable of delivering 16.5 A of current (peak) with a maximum rating of 16.5 A. The 5V STBY output should be capable of delivering a maximum of 1 A of current with a 1.5 A of peak. The output voltage hold-up time is 20 ms. will exceed 88% at 90 Vac and full load (measured at the end of PCB) for any ambient temperature within the operating range. The efficiency at 20% load and 90/115/132 Vac shall exceed 80% (at the end of the PCB). Standby Mode Efficiency: During main power off condition, the power supply unit will draw no more than 1 W from the AC outlet at 115 VAC, 60 Hz when a load of 0.5 W is applied to its +5V STBY rail. Protections • • • • Over Current Short Circuit Over Voltage Over Temperature Schematics The schematics of the reference design are shown in this section. Figure 2 shows the schematic for the NCP1562 active clamp converter section of the reference design, Figure3 shows the standby section and Figure 4 shows the control section. http://onsemi.com 5 L + L8 ~ C11 - BR1 R13 N t J Q6 C7 C6 K C5 E C2 L10 C30 D10 R2 HVDC-VE HVDC-P Q2 http://onsemi.com 6 T3 C Figure 2. Main Board C27 R7 DRV1 R11 D R6 Q4 R12 T2 C32 C31 R10 R4 R1 D2 D1 J C9 R9 D14 D13 D11 AUXILIARY POWER CARD REMOTE R8 R5 C3 BIAS CURRENT COMP2 CURRENT COMP1 [email protected] BIAS GND RMTE R15 D12 Q3 R14 F DRV1 C10 HVDC-VE DRV2 12V AUX P-VCC K HVDC-P Q5 FROM CONTROL CARD HVDC-P HVDC-VE BIAS BIASGND DRV2 +5V 12V AUX P-VCC D4 R3 Q1 C8 L3 C4 +VE C14 +5V -VE C13 [email protected] TND331 CONTROL CARD C22 R14 R15 DRAIN NC NC GND http://onsemi.com 7 R20 C23 U1 Figure 3. NCP1014 - Standby Converter Section HVDC-VE HVDC-P D6 D9 C13 C24 D8 C25 R21 T1 C18 12V AUX P-VCC D7 C12 R16 1N5822 C16 D5 R13 C19 C17 C14 R22 C20 12V AUX S-VCC U2 R18 L11 R19 R17 R23 C21 C15 +5V TND331 U8 FB NC VCC NC D C28 R24 R25 HVDC-VE HVDC-P 12V AUX P-VCC R33 R30 R26 R27 C29 R28 R29 C32 R34 R31 C31 U3 U10 VIN VAUX UVOV OUT1 PGND FF CS OUT2 GND CSKIP RTCT TD SYNC SS VREF VEA C35 Q8 R32 C33 http://onsemi.com 8 Figure 4. NCP1562 - Active Clamp Forward Converter Section R63 Q7 R50 U9 R56 D12 D11 R61 C46 C38 R35 DRV2 DRV1 R58 C39 R40 C44 U6 C34 C26 C R59 + D13 U7B R39 R41 U7D + C43 R62 R54 R57 R52 R48 R44 R42 C36 R46 R45 R43 C41 R37 C37 U7A + R36 12V @ 16.6A R60 U7C C42 R47 U5 2.5V REF FEEDBACK F 12V @ 16.6A R55 R53 OUTPUT OVER CURRENT & SHORT CIRCUIT PROTECTION REMOTE ON/OFF SECTION - OUTPUT IS ON WHEN PIN IS HIGH REMOTE C40 R38 12V AUX S-VCC CURRENT COMP2 OUTPUT OVER VOLTAGE LATCH C45 + R51 R49 D C DRV2 DRV1 BIAS REMOTE CURRENT COMP1 12V @ 16.6A BIAS GND HVDC-VE 12V AUX P-VCC HVDC-P TND331 R65 R64 TND331 Bill of Materials The complete bill of materials for the power supply is given in this section. Table 5. Bill of Materials - Main Board REV:4 PRODUCT PART NO-SP001 SL. NO DESCRIPTION CIRCUIT REF A ASSEMBLY PCB, SS 1 BRIDGE RECTIFIER BR1 GBV806 1 VISHAY 2 THERMISTOR, NTC R13 2E, 15 mm 1 THINKING ELECTRONICS 3 CAPACITOR, BOX, X2CLASS C11 0.22 mF, 275 V 1 VISHAY 4 CAPACITOR, ELECTROLYTIC, +80%, -20% C2 820 mF, 250 V 1 JACKON / VISHAY 5 CAPACITOR, ELECTROLYTIC, +80%, -20% C3 4700 mF, 25 V 1 JACKON / VISHAY 6 CAPACITOR, ELECTROLYTIC, +80%, -20% C4 100 mF, 25 V 1 JACKON / VISHAY 7 CAPACITOR, CERAMIC, Y2 CLASS C5, C6, C7 2.2 nF, 250 V 3 EPCOS / VISHAY 8 CAPACITOR, CERAMIC, MLC C13 0.47 mF, 100 V 1 VISHAY 9 CAPACITOR, CERAMIC, MLC C10, C14 0.1 mF, 50 V 2 VISHAY 10 CAPACITOR, CERAMIC, +20%, -20% C8 103, 1 KV 1 VISHAY 11 CAPACITOR, CERAMIC, +20%, -20% C9 101, 1 KV 1 VISHAY 12 CAPACITOR, CERAMIC, SMD2220 C27 1 mF, 100 V 1 VISHAY / AVX 13 CAPACITOR, CERAMIC, 1206 C32 10 nF, 50 V 1 VISHAY 14 CAPACITOR, CERAMIC, 1206 C30 100 nF, 50 V 1 VISHAY 15 RES, 5%, SMD, 1206 R1, R4 2E2 2 VISHAY 16 RES, 5%, SMD, 1206 R6 10E 1 VISHAY 17 RES, 5%, SMD, 1206 R3 2K2 1 VISHAY 18 RES, 5%, SMD, 1206 R7, R14, R15 10K 3 VISHAY 19 RES, 5%, SMD, 1206 R10 47E 1 VISHAY 20 NICHROME WIRE R5, R8 NICHROME WIRE 2 CUSTOM PART VALUE QTY/ UNIT ST200WA-V3 MANUFACTURER PART NO MAKE ST200WA-V3 MAX CIRCUITS 21 RES, 5%, CFR, 0.5W R9 10E, 0.5 W 1 VISHAY 22 RES, 5%, SMD, 2512 R12 0.05E 1 VISHAY 23 RES, 5%, SMD, 2512 R11 0.018E 1 VISHAY 24 DIODE, UFR, SOT23 D1, D2, D4 BAS16 3 ON Semiconductor 25 DIODE, SMD MELF R2 1N4148 1 NXP 26 DIODE, RECTIFIER D10 1N4148 1 NXP 27 RESISTOR, SMD, 1206 C31 0E 1 28 ZENER DIODE, 400mW D11, D12, D13, D14 16 V 4 ONSEMI / NXP 29 TRANSISTOR, TO92 Q2 2SA1015 1 NXP http://onsemi.com 9 10 mm CATHODE TOWARDS GATE OF Q1 TND331 Table 5. Bill of Materials - Main Board REV:4 PRODUCT PART NO-SP001 SL. NO DESCRIPTION CIRCUIT REF PART VALUE QTY/ UNIT MANUFACTURER PART NO MAKE B HEAT SINK HS1 SP001HS1 1 CUSTOM REF DRAWING 1 MOSFET, TO220 Q1 STP4NK80ZP 1 ST ALTERNATIVE ALTERNATIVE OR 1 MOSFET, TO220 Q1 STP3NK60ZP 1 ST 2 MOSFET, TO220 Q4 STP14NK50Z 1 ST 3 TRIAC, TO220 Q6 BT139 1 NXP C HEAT SINK HS2 SP001HS2 1 CUSTOM 1 MOSFET, TO220 Q3, Q5 IRF3705N 2 IR D COMMON MODE CHOKE L8 12 mH, 5 A 1 CUSTOM E TOROID INDUCTOR L3 40 mH, 25 A 1 CUSTOM F ASSEMBLY TRANSFORMER T2 SP001ARD2 1 CUSTOM G ASSEMBLY TRANSFORMER T3 SP001DRVDR2 1 CUSTOM I ASSEMBLY CHOKE L10 3.3 mH, 1.5 A 1 CUSTOM J 3PIN POWER CONNECTOR, PCB MOUNTABLE J1 EMI30 1 ELCOM http://onsemi.com 10 REF DRAWING TND331 Table 6. Bill of Materials - Standby Converter Board REV:4 SL. NO DESCRIPTION A ASSEMBLY PCB, SS 1 CAPACITOR, CERAMIC, +20%, -20% PRODUCT PART NO-SP001 CIRCUIT REF PART VALUE QTY/ UNITS AUXILLARY BOARD MAKE CUSTOM C12 102, 1 KV 1 EPCOS / VISHAY 2 CAPACITOR, CERAMIC, Y2 CLASS C13 2.2 nF, 250 V 1 EPCOS / VISHAY 3 CAPACITOR, ELECTROLYTIC, +80%, -20% C14, C24 100 mF, 25 V 2 JACKON / VISHAY 4 CAPACITOR, ELECTROLYTIC, +80%, -20% C16, C17, C18 470 mF, 25 V 3 JACKON / VISHAY 5 CAPACITOR, ELECTROLYTIC, +80%, -20% C22 10 mF, 50 V 1 JACKON / VISHAY 6 CAPACITOR, CERAMIC, X7R, SMD, 1206 C15, C20, C19, C21, C25 100 nF, 50 V 5 VISHAY 7 CAPACITOR, CERAMIC, X7R, SMD, 1206 C23 1 nF 1 VISHAY 8 RES, 5%, SMD, 1206 R13 22E 1 VISHAY 9 RES, 5%, SMD, 1206 R16 120E 1 VISHAY 10 RES, 1%, SMD, 1206 R17 2K2 1 VISHAY 11 RES, 1%, SMD, 1206 R20 6K8 1 VISHAY 12 RES, 1%, SMD, 1206 (T.S.R.) R22 100K 1 VISHAY 13 RES, 1%, SMD, 1206 R23, R19 4K7 2 VISHAY 14 RES, 5%, CFR, 1W R15 220K 1 VISHAY 15 DIODE, UFR D5 1N5822 1 ON Semiconductor 16 DIODE, UFR D6, D8 UF4005 2 VISHAY 17 DIODE, SCHOTTKY D7 1N5819 1 ON Semiconductor 18 DIODE, RECTIFIER D9 1N4007 1 ON Semiconductor 19 IC, DIP8, PWM SWITCHER U1 NCP1014P 1 ON Semiconductor 20 IC, REF, TO92 U2 TL431 1 ON Semiconductor 21 IC, OPTOCOUPLER, DIP4 U8 PC817 1 FAIRCHILD SEMI 22 JUMPER J1, J2, R14 3 B ASSEMBLY TRANSFORMER T1 STAUXSP001RD2 1 CUSTOM C ASSEMBLY CHOKE L11 3.3 mH, 1.5 A 1 CUSTOM D BERG STICK 90o angle J6, J7 7PIN 2 - http://onsemi.com 11 TND331 Table 7. Bill of Materials - Active Clamp Forward Converter Board REV:4 SL. DESCRIPTION PRODUCT PART NO-SP001 CIRCUIT REF NO PART VALUE QTY / CONTROL UNITS BOARD MAKE A ASSEMBLY PCB, DS 1 CAPACITOR, CERAMIC, X7R, SMD, 1206 C33, C34, C35, C37, C40, C44, C46 (Note 2) 100 nF, 50 V 7 VISHAY 2 CAPACITOR, CERAMIC, X7R, SMD, 1206 C28 10 nF, 50 V 1 VISHAY 3 CAPACITOR, CERAMIC, X7R, SMD, 1206 C39 10 nF, 50 V 1 VISHAY 4 CAPACITOR, CERAMIC, X7R, SMD, 1206 C29 470 pF, 50 V 1 VISHAY 5 CAPACITOR, CERAMIC, MLC C26 0.47 mF, 50 V 1 VISHAY 6 CAPACITOR, CERAMIC, X7R, SMD, 1206 C31 220 pF, 50 V 1 VISHAY 7 CAPACITOR, CERAMIC, X7R, SMD, 1206 C32 330 pF, 50 V 1 VISHAY 8 CAPACITOR, CERAMIC, X7R, SMD, 1206 C38 1 nF, 50 V 1 VISHAY 9 CAPACITOR, ELECTROLYTIC, +80%, -20% C45 10 mF, 63 V 1 JACKON/VISHAY 10 CAPACITOR, ELECTROLYTIC, +80%, -20% C43 4.7 mF, 63 V 1 JACKON/VISHAY 11 RES, 5%, SMD, 1206 R24, R26, R28 2M 3 VISHAY 12 RES, 5%, SMD, 1206 R30 160K 1 VISHAY 13 RES, 1%, SMD, 1206 R25, R27, R29, R40 100K 4 VISHAY 14 RES, 1%, SMD, 1206 R31 27K 1 VISHAY 15 RES, 1%, SMD, 1206 R32, R59 470K 2 VISHAY 16 RES, 5%, SMD, 1206 R33, R39, R53, R55 1K 4 VISHAY 17 RES, 5%, SMD, 1206 R34, R56 3.3K 2 VISHAY 18 RES, 1%, SMD, 1206 R35 820E 1 VISHAY 19 RES, 1%, SMD, 1206 R36 220E 1 VISHAY 20 RES, 1%, SMD, 1206 R37, R60 39K 2 VISHAY 21 RES, 1%, SMD, 1206 (T.S.R.) R64 120K 1 VISHAY 22 RES, 5%, SMD, 1206 R38, R54, R61, R62 2.2K 4 VISHAY 23 RES, 5%, SMD, 1206 R50 1.5K 1 VISHAY 24 RES, 1%, SMD, 1206 R52, R58, R63, R65 10K 4 VISHAY 25 TRIMPOT, MULTITURN R44 10K 1 BOURNS 26 RES, 1%, SMD, 1206 R43, R57 18K 1 VISHAY 27 RES, 1%, SMD, 1206 R51 220K 1 VISHAY 28 RES, 1%, SMD, 1206 (Note 3) R66 20K 1 VISHAY 29 DIODE, UFR, SOT23 D12, D13 BAS16 2 ON Semiconductor 30 TRANSISTOR, TO92 Q7 2N2222A 1 ON Semiconductor 31 SCR, TO92 Q8 2N6565 1 NXP 32 IC, SO-16, PWM SWITCHER U3 NCP1562A 1 ON Semiconductor 33 IC, REF, TO92 U5, U6 TL431 2 ON Semiconductor 34 IC, OP-AMP SOP14 U7 LM324 1 ON Semiconductor 35 IC, OPTOCOUPLER, DIP4 U9, U10 PC817 2 FAIRCHILD SEMI 36 NOT USED R42, R45, R46, R47, R48, R49, C42, D11, C36 B BERG STICK 90o angle J1, J2 7PIN 2 C HEAT SINK (Note 4) HS3 SP001HS3U 1 2. MOUNT C46 ON R58 3. PCB FOOT PRINT NOT AVAILABLE, SOLDER DIRECTLY ACROSS THE CHIP 4. OUTER HEATSINK http://onsemi.com 12 CUSTOM 8 CUSTOM TND331 Performance Results Efficiency Efficiency at Different Line and Load Conditions Input Voltage 20% Load 50% Load 100% Load 90 Vac 88.45% 90.54% 88.48% 100 Vac 87.84% 90.40% 88.89% 110 Vac 87.26% 90.26% 89.09% 120 Vac 85.71% 90.15% 89.71% 130 Vac 85.49% 90.35% 90.04% Standby Power Ripple Measurements The measured input (standby) power at 110 Vac and no load on the outputs (with 12 V output disabled) is 488 mW. The measured p-p ripple for the 12 V output was 80mV p-p (max) and the ripple for the 5 V output is 30 mV p-p (max). http://onsemi.com 13 TND331 Start-up and Shutdown Waveforms Output turn on and off waveforms. Ch1: 5 V Output Ch1: 5 V Output Ch2: 12 V Output 110 Vac Input 5V@1A 12 V @ 16.5 A 110 Vac Input 5V@1A 12 V @ 16.5 A Figure 5. Output Turn On Waveform Figure 6. Output Turn On Waveform Ch1: 5 V Output 110 Vac Input 5V@1A 12 V @ 16.5 A Ch1: 12 V Output 110 Vac Input 5V@1A 12 V @ 16.5 A Figure 7. Output Turn On Waveform Figure 8. Output Turn Off Waveform Ch1: 12 V Output Ch1: 12 V Output 110 Vac Input 5V@1A 12 V @ 16.5 A 110 Vac Input 5V@1A 12 V @ 16.5 A ~ 8.25 A Figure 9. Output Turn Off Waveform Figure 10. Transient Response http://onsemi.com 14 TND331 Figure 11. Board Picture Magnetic Component Information 1. Driver Transformer: SP001DRVDR2 1. Transformer Core: EE16 Sl No. Winding Description 1 Primary winding W1 2. Bobbin: EE16 VERTICAL 3+3 Pins Turns No Of Wires SWG Layers Start Finish 18 2 30 1 3 1 30 1 6 4 2 Layers of 2 Mil Tape Insulation 2 Secondary winding W2 40 2 2. Auxiliary / Standby Power Supply Transformer: STAUXSP001RD2 1. Transformer Core: EFD20 2. Bobbin: EFD20 Horizontal 4+4 Pins Sl No. Winding Description Turns No Of Wires SWG Layers Start Finish 1 Primary winding W1 102 1 32 1 3 1 28 1 4 2 28 1 8 7 28 1 6 5 2 Layers of 2 Mil Tape Insulation 2 Bias Winding W2 3 Secondary Winding W3 12 1 2 Layers of 2 Mil tape Insulation 5 3 2 Layers of 2 Mil tape Insulation 4 Secondary Winding W4 12 1 Gap Length: 3.15 mils. Primary Inductance: 2055 mH Estimated Transformer Primary Leakage Inductance to be less than 5% of Primary Inductance http://onsemi.com 15 TND331 3. Main Transformer: SP001ARD2 1. Transformer Core: PQ 32/20 2. Bobbin: PQ 32/20, 6 + 6 Pins SN Winding Description Turns No.of wires SWG Layers Start Finish 1 Split Primary Winding W1 7 8 0.4/0.5 mm 1 2,3 FL1 2 Gate drive winding W2 2 2 28 1 7 9 3 Gate drive winding W3 1 2 28 1 9 12 10 Mils foil, 16 mmWidth 1 10, 11 8 1 FL1 4, 5 2 Layers of 2 Mil Tape Insulation 2 Layers of 2 Mil Tape Insulation 4 Secondary Winding W4 3 - Note: For winding 4 use 15SWG Wire leads to solder the foil 2 Layers of 2 Mil Tape Insulation 5 Split Primary winding W5 6 8 0.4/0.5 mm Primary Inductance 900 mH across pins 2 & 5, + 0%, - 10% Estimated Transformer Primary Leakage Inductance to be less than 5% of Primary. Wind Uniformly all windings @ spread it evenly across the entire cross section of the bobbin 4. Output Inductor: T27 Toroid T27- MicroMetal Wire gauge 15 SWG, 2 wires, 15 Turns Inductance 40 mH Amps 20 A • The thermal performance and efficiency can be further Potential Improvements In evaluating the results of the reference design, certain areas of further performance improvements are identified and listed below. • The drive circuit for the active clamp and the main FET can be simplified using the integrated high-side / low-side driver like the NCP5181 instead of the gate drive transformer. improved by choosing more optimal FETs for the secondary synchronous rectifiers and also by optimizing the drive circuit for these devices. It is estimated that there is additional power loss of 1-2% in the current design that is attributable to the inefficient switching of the synchronous rectifiers. http://onsemi.com 16 TND331 APPENDIX References: • Draft Commission Communication on Policy Instruments to Reduce Stand-by Losses of Consumer Electronic Equipment (19 February 1999) - http://energyefficiency.jrc.cec.eu.int/pdf/consumer_electronics_communication.pdf • European Information & Communications Technology Industry Association - http://www.eicta.org/ • http://standby.lbl.gov/ACEEE/StandbyPaper.pdf CECP (China): • http://www.cecp.org.cn/englishhtml/index.asp Energy Saving (Korea): • http://weng.kemco.or.kr/efficiency/english/main.html# Top Runner (Japan): • http://www.eccj.or.jp/top_runner/index.html EU Eco-label (Europe): • http://europa.eu.int/comm/environment/ecolabel/index_en.htm • http://europa.eu.int/comm/environment/ecolabel/product/pg_television_en.htm EU Code of Conduct (Europe): • http://energyefficiency.jrc.cec.eu.int/html/standby_initiative.htm GEEA (Europe): • http://www.efficient-appliances.org/ • http://www.efficient-appliances.org/Criteria.htm Energy Star: • http://www.energystar.gov/ • http://www.energystar.gov/index.cfm?c=product_specs.pt_product_specs 1 Watt Executive Order: • http://oahu.lbl.gov/ • http://oahu.lbl.gov/level_summary.html GreenPoint is a trademark of Semiconductor Components Industries, LLC (SCILLC). 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