TND399/D Rev. 0, February-10 216 W All in One Power Supply Reference Design Featuring NCP1605, NCP1397 and NCP4303 Documentation 1 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. The design intent is to demonstrate that efficiencies beyond 85% are achievable cost effectively utilizing ON Semiconductor provided ICs and discrete components in conjunction with other inexpensive components. It is expected that users may make further refinements to meet specific performance goals. 2 1 2 Overview`......................................................................................................4 Specification .................................................................................................5 2.1 Efficiency requirements ..........................................................................5 2.2 Input Voltage ..........................................................................................5 2.3 Main Power Supply Output voltage: .......................................................5 2.4 Standby Power Supply: ..........................................................................6 3 Architecture Overview...................................................................................6 3.1 Primary Side: Power Factor Correction Stage ........................................6 3.2 Primary Side: Half bridge resonant LLC Converter.................................7 3.2.1 The Half Bridge Resonant LLC topology .........................................7 3.2.2 LLC elements used in the reference design ....................................8 3.2.3 LLC Gain Characteristics.................................................................9 3.2.4 LLC Controller: NCP1397................................................................9 3.2.5 More information..............................................................................9 3.3 Secondary Side: Synchronous Rectification ...........................................9 3.3.1 Why Synchronous Rectification .......................................................9 3.3.2 Synchronous Rectification Controller: NCP4303 ...........................11 4 Performance Results ..................................................................................12 4.1 Total Efficiency .....................................................................................12 4.2 Light load Efficiency..............................................................................12 4.2.1 Discharging X2 Capacitors ............................................................12 4.2.2 Results ..........................................................................................13 5 Detail losses distribution .............................................................................14 5.1 Power Factor ........................................................................................14 6 Board Picture ..............................................................................................15 7 Schematic ...................................................................................................16 8 Board Layout ..............................................................................................17 9 Board Part list .............................................................................................21 10 Resources/Contact Information ..................................................................25 11 Appendix.....................................................................................................25 11.1 Link to ON Semiconductor’s web site ...................................................25 11.2 Industry information links: .....................................................................25 11.3 Additional collateral from ON Semiconductor .......................................25 11.4 Other ON Semiconductor Discrete Products ........................................25 3 1 Overview` All-in-One computers have taken over a significant share of the Desktop PC market. All OEM manufacturers have released models. For those computers, an attractive, slim and compact design is necessary. Therefore, the power supply that is embedded in the unit must be extremely efficient. This reference design demonstrates a 216 W single-output power supply for an All-in-One computer. This design achieves a maximum efficiency of 93% at 50% load and 230 Vac, and 91.3% at 50% load and 115 Vac. All efficiency measurements were obtained in the end application. The design manual provides a detailed view of the performance achieved with this design in terms of efficiency, performance, and other key parameters. In addition, a detailed list of the bill-of-materials (BOM) is also provided. ON Semiconductor can also provide technical support to help customers design and manufacture a similar power supply customized to their specific requirements. The results achieved in this design were possible due to the use of advanced new components from ON Semiconductor. These new ICs not only accelerates the overall development cycle for this new design, but helped achieve the high efficiencies while balancing overall cost. Detailed schematics are included later in this design manual. Figure 1: Reference Design Architecture Simplified Block Diagram As seen in Figure 1, the first stage, an active Power Factor Correction (PFC) stage, is built around a Frequency Clamped Critical Conduction Mode (FCCrM) PFC controller, the NCP1605. The second stage features a resonant half-bridge LLC topology using ON Semiconductor’s controller, the NCP1397. This topology ensures maximum efficiency and minimizes EMI. On the secondary side, this architecture uses a synchronous rectification scheme built around ON Semiconductor’s NCP4303 controller to generate a 12 V output. 4 2 Specification 2.1 Efficiency requirements This reference design exceeds the 80 PLUS Silver (www.80pls.org), ENERGY STAR® 5.0 (www.energystar.gov), and Climate Savers Computing Initiative (CSCI) Step 3 (www.climatesaverscomputing.org) efficiency targets for desktop PC single-output power supplies. Table 1 hereafter shows a summary of the efficiency targets from these different organizations. Single-Output Levels Efficiency (%) 20% of 50% of 100% of rated rated rated output output output power power power Specification • Single-Output • Non-Redundant • PFC 0.9 at 50% 81% 85% 81% Start June 2007 • Single-Output • Non-Redundant • PFC 0.9 at 50% 85% 89% 85% Start June 2008 • Single-Output • Non-Redundant • PFC 0.9 at 50% 88% 92% 88% Start June 2010 • Single-Output • Non-Redundant • PFC 0.9 at 50% 90% 94% 91% Target Table 1 2.2 • 2.3 • Effective Date Input Voltage Universal input 90 Vac to 265 Vac, 47-63 Hz Main Power Supply Output voltage: 12 V / 15 A 5 2.4 • • • Standby Power Supply: 50 mA in off mode 100 mA in sleep mode 5 A in active mode 3 Architecture Overview The architecture selected is designed around a succession of conversion stages as illustrated in Figure 1. The first stage is a universal input, active power factor boost delivering a constant output voltage of 385 V to the second stage, the halfbridge resonant LLC converter. On the secondary side, this architecture uses a synchronous rectification scheme built around ON Semiconductor’s NCP4303 controller in order to generate a +12 V output. The semiconductor components, supporting this All in One PC reference design are the NCP1605 PFC controller, the NCP1397 half-bridge resonant controller and the NCP4303 synchronous rectification. 3.1 Primary Side: Power Factor Correction Stage ON Semiconductor offers solutions for 3 PFC operation modes: Operating Mode IL IL IL Tclamp Main Feature Continuous Conduction Mode (CCM) Always hard-switching Inductor value is largest Minimized rms current e.g.: NCP1654 Critical conduction Mode (CrM) Large rms current Switching frequency is not fixed e.g.: NCP1606 Frequency Clamped Critical Conduction Mode (FCCrM) Large rms current Frequency is limited Reduced coil inductance e.g.: NCP1605 Tclamp Table 2: PFC operation modes For a 216 W output power design, a Frequency Clamped Critical Conduction Mode (FCCrM) approach is the most suitable one because of its high efficiency and smooth EMI signature. The NCP1605 operates in this mode. The circuit also incorporates protection features for a rugged operation together with some dedicated circuitry to lower the power consumed by the PFC stage in no load conditions. 6 3.2 Primary Side: Half bridge resonant LLC Converter 3.2.1 The Half Bridge Resonant LLC topology The Half Bridge Resonant LLC topology, that is a member of the Series Resonant Converters (SRC), is widely used in applications where high power density is necessary. The Half Bridge Resonant LLC converter is an attractive alternative to the traditional Half Bridge (HB) topology for several reasons. Advantages include: • ZVS (Zero Voltage Switching) capability over the entire load range: Switching takes place under conditions of zero drain voltage, which results is nearly nearly zero turn-on losses. This improves the EMI signature compared to the HB, which operates under hard-switching conditions. • Low turnoff current: Switches are turned off under low current conditions, lowering turn-off losses compared to the HB topology. • Zero current turnoff of the secondary diodes: When the converter operates under full load, the output rectifiers are turned off under zerocurrent conditions, reducing the EMI signature. • No increased component count: The component count is virtually the same as the classical half bridge topology. Figure 2 shows the structure of this resonant converter. A 50 % duty-cycle halfbridge delivers high-voltage square waves swinging from 0 V to the input voltage VIN to a resonating circuit. By adjusting the frequency via a voltage-controlled oscillator (VCO), the feedback loop can adjust the output level depending on the power demand. Vin Qb Vout 1 Cs N:1 Ls 6 5 7 Lm C Q RL 9 Figure 2 The resonating circuit is made of a capacitor, Cs, in series with two inductors, Ls and Lm. One of these inductors, Lm, represents the magnetizing inductance of the transformer and creates one resonating point together with Ls and Cs. The 7 reflection of the load across this inductor will either make it disappear from the circuit (Lm is fully short-circuited by a reflected RL of low value at heavy load currents) or will make it stay in series with the inductor Ls in light load conditions. As a result, dependant on the loading conditions, the resonant frequency will move between a minimum and a maximum: The steady state frequency of operation depends on the power demand. For a low power demand, the operating frequency is rather high, away from the resonating point. On the contrary, at high power, the switching frequency decreases approaching resonant frequency to deliver the necessary amount of current to the load. This topology behaves like a frequency dependent divider. Figure 3: Substitutive schematic of the LLC resonant converter 8 ⋅ RL π ⋅ n 2 ⋅η Where: RL is the real loading resistance n is the transformer turns ratio η is the expected efficiency Rac = 2 3.2.2 LLC elements used in the reference design • Transformer: o Primary inductance Lm= 430 uH o Leakage inductance Llk= 55 uH o Turn ratio primary to secondary n = 17.5 o Turn ratio primary to auxiliary naux = 11.6 • Resonant coil: Ls= 30 uH • Resonant capacitor: Cs= 2 x 12 nF 8 3.2.3 LLC Gain Characteristics 0.100 Full load 0.090 0.080 fop= 87 kHz@ Vbulk=350 Vdc Gain [-] 0.070 fop= 103 kHz@ Vbulk=385 Vdc fop= 124 kHz@ Vbulk=420 Vdc 0.060 0.050 0.040 0.030 0.020 0.010 0.000 1.00E+04 1.00E+05 1.00E+06 Frequency [Hz] Figure 4: Gain Characteristics Please note that the selected resonant tank provides narrow operating frequency range. 3.2.4 LLC Controller: NCP1397 The heart of the half-bridge resonant LLC converter stage is the NCP1397. Thanks to its proprietary high-voltage technology, this controller includes a bootstrapped MOSFET driver for half-bridge applications that accept bulk voltages up to 600 V. Multiples protections (e.g. immediate shutdown or timer-based event, brownout, broken optocoupler detection, etc), contribute to a safer converter design, without additional complex circuit. An adjustable dead time also helps lower the shootthrough current contribution as the switching frequency increases. 3.2.5 More information More information about LLC structure can be found in the ON Semiconductor application note AND8311/D (Understanding the LLC Structure in Resonant Applications). 3.3 Secondary Side: Synchronous Rectification 3.3.1 Why Synchronous Rectification Figure 5 highlights the benefits of using synchronous rectification at higher output current compared to the standard approach of using diodes. 9 6 4 Losses [W] Losses calculated for one Shottky diode 2.33 % of output power 5 Point at which Sync Rec has advantages 3 Losses calculated for one SR MOSFET (including driving) 2 2.17 % of output power 1 1.4 % of output power 0 0 3 6 9 12 15 18 Output current [A] Figure 5: Synchronous Rectification benefits Figure 5 also shows that in light load conditions, the Synchronous Rectification must be turned off. Figure 6 details how the NCP4303 is disabled when the output current is low. Figure 6: Syn. Rectification controller is shut down when the output current is low 10 3.3.2 Synchronous Rectification Controller: NCP4303 The 12 V output generated by the half-bridge resonant LLC converter is rectified using a proprietary synchronous rectification scheme built around two NCP4303 controllers and two external single N-channel MOSFETs. Key features offered by the NCP4303: • Operates in CCM and DCM Applications • True Secondary Zero Current Detection with Adjustable Threshold • Automatic Parasitic Inductance Compensation • 50 ns Turn off Delay from CS to Driver • Interface to External Signal for CCM Mode • Trigger Input to enter Standby Mode • Adjustable Min Ton Independent of Vcc Level • Adjustable Min Toff Independent of Vcc Level • 5 A / 2.5 A Peak Current Drive Capability • Voltage range up to 30 V (Gate drive clamp of either 12 V or 5 V) • Low startup and standby current consumption 11 4 Performance Results Efficiency [%] 4.1 Total Efficiency 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 230 0 3 6 9 12 110 15 18 Output current [A] Figure 7: Efficiency Measurements AC input 110 VAC 230 VAC 20% load Meas. Spec. 89.6% 85% 90.6% 85% Total Efficiency 50% load 100% load Meas. Spec. Meas. Spec. 91.3% 89% 89.1% 85% 93.0% 89% 91.9% 85% Conclusion Passed Passed Table 3: Efficiency results 4.2 Light load Efficiency 4.2.1 Discharging X2 Capacitors Achieving the lowest possible standby power is one of the goals of this reference design. X2 capacitors are used to minimize the conducted EMI signature of the power supply. For safety reasons, it is mandatory to discharge those capacitors once the application is unplugged. Often resistors perform this function. This result in power always being dissipated, it significantly alters the efficiency of the power supply in light load condition. In this reference design, dedicated circuitry has been used to improve this power loss (see Figure 8). The capacitor C3 is discharged via R5 and R6 that are only connected when the mains is gone and when Q6 is turned on. 12 Figure 8: an efficient way to discharge X2 capacitors 4.2.2 Results 2000 No load 1800 50 mA load Consumption [mW] 1600 1400 1200 1000 800 600 400 200 0 90 115 140 165 190 AC voltage [V] 215 240 Figure 9: Light load efficiency measurements 13 265 5 Detail losses distribution 9 Vin=110 Vac Vin=230 Vac 8 7 Pd [W] 6 5 4 3 2 1 re ct ifi er .& sw SR di od e er or m PF C Tr an sf Br id ge re ct . co il PF C ET s R es on an tc oi l M O SF LL C O ut pu ts w itc h 0 Figure 10: Losses Distributions 5.1 Power Factor AC input 20% load 50% load 110 VAC 0.954 0.984 230 VAC 0.756 0.881 Power Factor 100% load Specification PF > 0.9 @ 0.992 100% and 50 % of rated output 0.940 power Table 4 14 Conclusion Passed Passed 6 Board Picture PFC stage Secondary capacitor Output connector SR MOSFETs and STBY switch on cooler EMI filter LLC stage Resonant inductor Transformer NCP1397B LLC cnt. NCS1002 regulator LM324 amplifier 2 x NCP4303 SR cnt. 15 NCP1605 PFC cnt. 7 Schematic Figure 11: Power Supply Schematic 16 8 Board Layout Figure 12: PCB top side 17 Figure 13: Top side components 18 Figure 14: PCB bottom side 19 Figure 15: Bottom side components 20 9 Board Part list Parts Qty Value Device B1 1 KBU8R C1, C3 2 22u C10 1 120u C11, C29 C13 C14, C34, C38, C44, C48, C52, C57, C58, C60, C69 C15 C16, C17 C2 2 1 10 1 2 1 1u 820n 100n 1u 22n 1n C20, C21, C22, C23, C24, C25, C26 7 470uF/16V C27, C66 C28, C67 C31 C35 C36, C43 2 2 1 1 2 220n 22n 330n 220p 100p C4 1 10u/50V C40 C42 C46, C47 C49 C5, C32 C50 C51 1 1 2 1 2 1 1 6.8n 470n 470n 47p 33n 560p 10n C53 1 220u/25 C54, C55 C56, C65 C59 C6, C7, C19 C63 2 2 1 3 1 10u/15V 2n2 47n 1u 1uF C64 1 4u7/35V C68 1 100n BRIDGE RECTIFIER ELECTROLYTIC CAPACITOR ELECTROLYTIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR ELECTROLYTIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR ELECTROLYTIC CAPACITOR CERAMIC CAPACITOR X2 CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR ELECTROLYTIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR CERAMIC CAPACITOR POLYESTER CAPACITOR CERAMIC CAPACITOR ELECTROLYTIC CAPACITOR CERAMIC CAPACITOR 21 C8, C39 C9, C18 CY1 D1, D2, D7, D11, D19, D20, D26, D30 D12 D14 D22, D23, D31, D33, D34, D35 D3 D32 D4 D5 D6 D8, D21 D9, D13, D17 F1 IC1, IC2 IC3 IC4 IC5 IC6 IC7 L1 L2, L4 L3 2 2 1 8 1 1 6 1 1 1 1 1 2 3 1 2 1 1 1 1 1 1 2 1 3n9 12n 2n2/Y1 MMSD4148 MM3Z18VT1G MMSZ5236BT1G NSR0340HT1G M1MA142WKT1G MURA160 1N5408 MMSZ16 MURF550MFG 12CWQ06FNDPAK MRA4007 5A NCP4303A NCP1605 NCS1002 LM358D NCP1397B TLV431 200uH L5 1 82721A L6, L7 OK1, OK2 Q1, Q2, Q14, Q16 Q10 Q11, Q15 Q4 Q5, Q12 Q6 Q7 Q8 Q9, Q13 R1, R9, R15, R57 R103 2 2 4 1 2 1 2 1 1 1 2 4 1 70nH PC817 BC846A BC807-16L IRFB3206 IPP20N60 STP12NM50FP MPSA44 BC856B 15N04N 2N7002E 22R 62k 30uH CERAMIC CAPACITOR CERAMIC CAPACITOR Y1 CAPACITOR DIODE ZENER DIODE ZENER DIODE DIODE DOUBLE DIODE DIODE DIODE ZENER DIODE DIODE DOUBLE DIODE DIODE FUSE SR CONTROLLER PFC CONTROLLER CV/CC CONTROLLER OPERATION AMPLIFIER RESONANT CONTROLLER VOLTAGE REFERENCE INDUCTOR INDUCTOR INDUCTOR COMMON MODE INDUCTOR INDUCTOR TRANSISTOR TRANSISTOR TRANSISTOR N-MOSFET N-MOSFET N-MOSFET TRANSISTOR TRANSISTOR N-MOSFET MOSFET RESISTOR SMD RESISTOR SMD 22 R105 R106 R108 R11, R12, R22, R23, R37, R38, R55, R56 R110, R111 R114 R116 R117 R123 R126 R127 R13, R20 R135, R141 R137 R142 R16, R25, R36 R18 R19, R90 1 1 1 8 2 1 1 1 1 1 1 2 2 1 1 3 1 2 24k 200R 560k 1.8M 6k8 2.7k 27k 2.2k 18R 22k 9.1k 220 7.5k 330 200k 1M8 220k 27R RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD HV RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD R2, R42, R45, R69, R70, R86, R87, R95, R121, R122, R125, R130, R144, R145 14 1k RESISTOR SMD R21 R24, R109, R124, R133 R26 R27 R28, R80, R81 R29, R120 R3, R17 R30, R33, R35, R39, R48, R51, R52, R71, R76, R77, R107, R113, R148 R31, R91 R34, R67 R4, R100 R40, R59 R41 R43 R46 R47 R5, R14 R50 1 4 1 1 3 2 2 13 2 2 2 2 1 1 1 1 2 1 33R 5.6k 1k 2R2 10R 47k 100R 10k 56k 16k 100k 0R 20k 470 0.1R 10 47k 51R RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR SMD RESISTOR RESISTOR-SMD HV RESISTOR SMD RESISTOR-SMD 23 R53 R54, R134, R138 R58 R6, R49 R60 R61 R62, R79 R63 R64, R132 R65, R66 R7 R73 R74 R75, R112, R140 R78, R139 R8 R82 R83 R85 R92, R147 R94, R97, R136 R96, R146 R98 R99, R128 TR1 1 3 1 2 1 1 2 1 2 2 1 1 1 3 2 1 1 1 1 2 3 2 1 2 1 8.2k 6.2k 7k5 4.7R 1M8 0R002 22k 47R 10k@25deg 4R7 4M7 1k 5k6 22k 150k 330R 430k 51k 18k 13k 15k 330k 6.8k 43k RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD THERMISTOR RESISTOR-SMD RESISTOR RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD RESISTOR-SMD TRANSFORMER 24 10 Resources/Contact Information Data sheets, applications information and samples for the ON Semiconductor components are available at www.onsemi.com. Links to the datasheets of the main components used in this design are included in the Appendix. Authors of this document are Jaromir Uherek, Roman Stuler and Christophe Warin 11 Appendix 11.1 Link to ON Semiconductor’s web site • ON Semiconductor Home Page 11.2 Industry information links: • • • • • ENERGY STAR 80 PLUS Efficiency Requirements Climate Savers Computing Initiative IEC61000-3-2 Requirements European Union (EU) Energy Star Page 11.3 Additional collateral from ON Semiconductor • • • • • • NCP1605: Enhanced, High Voltage and Efficient Standby Mode PF Controller NCP1397: High Perf. Resonant Mode Controller with Integrated High Voltage Drivers NCP4303: Secondary Side Synchronous Rectification Driver TLV431: Low Voltage Precision Adjustable Shunt Regulator NCS1002: CV/CC Secondary Controller LM358D: Single Supply Dual Operational Amplifier 11.4 Other ON Semiconductor Discrete Products • MMSD4148 • MM3Z18VT1G • MMSZ5236BT1G • NSR0340HT1G • M1MA142WKT1G • MURA160 • 1N5408 • MMSZ16 • MURF550MFG • MRA4007 • BC846A • BC856 BC807-16L 25