DN05044/D High Efficiency, <10 mW Standby PFC + QR Adapter http://onsemi.com Circuit Description The NCP1937 is a combination controller which integrates a power factor correction (PFC) and quasi-resonant flyback controller in an SO−20 package. It integrates all the functionality necessary to implement a compact and highly efficient Switched Mode Power Supply for an adapter application. The PFC stage exhibits near-unity power factor while operating in a Critical Conduction Mode (CrM) with a maximum frequency clamp. The circuit incorporates all the features necessary for building a robust and compact PFC stage while minimizing the number of external components. The quasi-resonant current-mode flyback stage features a proprietary valley-lockout circuitry, ensuring stable valley switching. This system works down to the 4th valley and toggles to a frequency foldback mode with a minimum frequency clamp beyond the 4th valley to eliminate audible noise. Skip mode operation allows excellent efficiency in light load conditions while consuming very low standby power consumption. Synchronous rectification is implemented on the secondary side for increased efficiency with the NCP4304. The NCP4355B is a secondary side CCCV controller that detects no load conditions and communicates to the primary controller enabling an ultra-low frequency skip mode for reduced standby consumption. This enables the system to achieve < 10 mW no load standby. DESIGN NOTE Key Features High-Voltage Startup Circuit and Active Input Filter Capacitor Discharge Circuitry for Reduced Standby Power Integrated High-Voltage Switch Disconnects PFC Feedback Resistor Divider to Reduce Standby Power Low Consumption Power Savings Mode for Reduced Standby Power Adjustable PFC Disable Threshold Based on Output Power Fault Input for Severe Fault Conditions, NTC Compatible (Latch and Auto-Recovery Options) Boost Diode Short-Circuit Protection Valley Switching Operation with Valley-Lockout for Noise-Free Operation Frequency Foldback with Minimum Frequency Clamp for Low Standby Mode Minimum Frequency Clamp Eliminates Audible Noise Table 1. DEVICE DETAILS Device Application Input Voltage Output Power Topology I/O Isolation NCP1937 R1 NCP4304 NCP4355 Adapter 90 to 264 Vac Up to 85 W PFC + QR Combo Isolated Table 2. OTHER SPECIFICATIONS Output Specification Output Voltage Nominal Current 4.25 A No Load Standby < 10 mW Min Current Zero Semiconductor Components Industries, LLC, 2013 May, 2013 − Rev. 1 20 Vdc nominal 1 Publication Order Number: DN05044/D DN05044/D CIRCUIT SCHEMATIC http://onsemi.com 2 DN05044/D MAGNETICS DESIGN − FLYBACK TRANSFORMER http://onsemi.com 3 DN05044/D MAGNETICS DESIGN − PFC INDUCTOR http://onsemi.com 4 DN05044/D EFFICIENCY PLOTS Light Load Efficiency Figure 1. Output Power vs. Efficiency − Light Load Efficiency Average Efficiency Figure 2. Output Power vs. Efficiency − Average Efficiency http://onsemi.com 5 DN05044/D DESCRIPTION OF KEY FEATURES Power Savings Mode The NCP1937 features a low consumption operating mode called Power Savings Mode (PSM). PSM can be used to achieve very low input power dissipation when the application is operating at no load. When the controller enters PSM it stops switching and shuts down much of its functionality enabling the controller to operate with a bias current of < 70 mA. While most of the controller’s functions are shut off, the input filter capacitor discharge is required to remain active should the application be unplugged. In order to provide a bias supply for the capacitor discharge function the controller regulates VCC to 11 V (typical) by alternating turn-on of the high voltage startup circuits. Each startup turns on once every line cycle when its respective HV pin voltage exceeds 30 V (typical) provided that VCC is below 11 V and the complementary startup had turned on during the previous half cycle. The startup circuit will shut off once VCC exceeds 11 V. There is no hysteresis in the internal regulation loop ensuring that VCC will be below its regulation level during the next half cycle. This method of regulating VCC makes it possible to have a low average voltage at the HV pins allowing the application to achieve very low power dissipation. Power Savings Mode Operation Ch. 1 (Yellow): BOX2 Ch. 3 (Purple): HVX2 Ch. 4 (Green): VCC (AC Coupled) Measured data with 2 wire connection 4.82 mW at 115 VAC 8.68 mW at 265 VAC Figure 3. Power Saving Mode Active X2 Capacitor Discharge pins when the voltage on those pins becomes static. A line removal timer is then initiated. 2) When the line removal timer expires, drive pulses are halted and the VCC pin is rapidly discharged. 3) Once VCC reaches VCC(off) the high voltage startups are turned on transferring the stored charge from the input filter capacitors onto the VCC capacitor. 4) Being that the VCC capacitor is much larger than the filter capacitors, the voltage on the filter capacitors will quickly discharge to a safe level without restarting the controller. The NCP1937 features integrated active input filter (X2) capacitor discharge, eliminating the need for external discharge resistors which are major contributors to the total power dissipation in light load and standby mode operation. The integrated discharge circuit is virtually lossless across all operating modes and only consumes power when it is needed to discharge the X2 capacitors. The discharge circuit works in the following manner: 1) Line voltage removal is detected at the HVX2 and BOX2 http://onsemi.com 6 DN05044/D 2 1 3 Ch. 1 (Yellow): VCC Ch. 2 (Blue): QR FET DRV Ch. 3 (Purple): VOUT Ch. 4 (Green): BOX2 Pin 4 Figure 4. Active X2 Capacitor Discharge Adjustable PFC Disable PFC Disable PFC Enable VAC IO VAC IO 90 2.5 A 90 3A 115 2.5 A 115 2.9 A 230 2.4 A 230 2.8 A 265 2.4 A 265 2.75 A Ch. 1 (Yellow): QR FET Drain Ch. 2 (Blue): QR FET DRV Ch. 3 (Purple): PFC FET DRV Ch. 4 (Green): PONOFF Voltage Figure 5. Adjustable PFC Disable http://onsemi.com 7 DN05044/D output power. This voltage is then compared internally to a reference voltage to determine when the PFC is enable and disabled. Reference the NCP1937 Design Tool for determining the values of the external resistor and capacitor. A waveform of the voltage on the PONOFF pin with the flyback switching waveforms is shown above demonstrating the modulation and averaging of the PONOFF current. Performance data from the demonstration board is shown alongside the waveform. In this application it was determined that enabling and disabling the PFC between 50–75% (2.125–3.19 A) of the full rated load provided the best average efficiency across the universal line range. In certain applications it is desired to turn the PFC converter off at lighter loads to optimize the system’s overall efficiency. The NCP1937 features integrated circuitry which measures the output power of the flyback converter and outputs a current proportional to the QR flyback’s output power from the PONOFF pin. The current proportional to output power is generated with a voltage-to-current (V/I) converter which sets a DC current based on the feedback voltage of the QR flyback. The DC current from the V/I converter is then pulse width modulated with a duty cycle equivalent to the demagnetization period of the QR flyback. External to the controller, a resistor and capacitor scale and average the current output from the PONOFF pin into a voltage proportional to the system’s POWER FACTOR Figure 6. Power Factor vs. Output Power http://onsemi.com 8 DN05044/D Table 3. BILL OF MATERIALS FOR 20 W NCP1126/1129 FLYBACK REF DES Qty. Description Value Tolerance Footprint Manufacturer Manufacturer PN Substitution C1, C2 2 Capacitor, Metallized Polypropylene 0.22 mF, 450 V 5% Through Hole, 10 mm Panasonic ECW−F2W224JAQ No C3 1 Capacitor, Electrolytic 82 mF, 450 V 20% Through Hole, 7.5 mm United Chemi-Con EKXG451ELL820MMP1S No C4 1 Capacitor, Ceramic, X7R 10 nF, 50 V 10% SMD, 1206 Vishay VJ1206Y103KXAAC Yes C5 1 Capacitor, Ceramic, X7R 6800 pF, 630 V 20% SMD, 1206 TDK C3216X7R2J682M No C6 1 Capacitor, Ceramic, X7R 100 pF, 1 kV 10% SMD, 1206 Johanson’s Dielectric 102R18W101KV4E No C7 0 PLACEHOLDER PLACEHOLDER SMD, 0603 PLACEHOLDER PLACEHOLDER Yes C8 1 Capacitor, Electrolytic 47 mF, 35 V 20% Through Hole, 2.5 mm Kemet ESH476M035AE3AA No C9 1 Capacitor, Ceramic, COG 4.7 pF, 50 V 0.25 pF SMD, 0603 TDK C1608COG1H4R7C Yes C10 1 Capacitor, Ceramic, X7R 1000 pF, 25 V 10% SMD, 0603 Vishay VJ0603Y102KXXCW1BC Yes C11, C12, C24 3 Capacitor, Ceramic, X7R 0.1 mF, 50 V 10% SMD, 0603 Yageo CC0603KRX7R9BB104 Yes C13 1 Capacitor, Ceramic, X7R 2.2 mF, 10 V 10% SMD, 0603 Taiyo Yuden LMK107B7225KA−T Yes C14 1 Capacitor, Ceramic, X7R 330 pF, 50 V 10% SMD, 0603 Yageo CC0603KRX7R9BB331 Yes C15 1 Capacitor, Ceramic, X7R 150 pF, 25 V 10% SMD, 0603 AVX 06033C151KAT2A Yes C16, C23 2 Capacitor, Ceramic, X7R 0.47 mF, 50 V 10% SMD, 0603 Taiyo Yuden UMK107B7474KA−TR Yes C17 1 Capacitor, Ceramic, X7R 100 pF, 25 V 10% SMD, 0603 Vishay VJ0603Y101KXXCW1BC Yes C18 1 Capacitor, Ceramic, COG 47 pF, 50 V 10% SMD, 0603 Vishay VJ0603A470KXAAC Yes C19, C20 2 Capacitor, Electrolytic 1000 mF, 35 V 20% Through Hole, 5 mm Panasonic EEU-FM1V102 No C21 1 Capacitor, Ceramic, X7R 47 nF, 50 V 10% SMD, 1206 Xicon 140-CC502B473K−RC Yes C22 1 Capacitor, Ceramic, X7R 0.22 mF, 25 V 10% SMD, 0805 Kemet C0805C224K3RACTU Yes C25 1 Capacitor, Ceramic, X7R 2.2 mF, 25 V 10% SMD, 0805 TDK TMK212B7225KG−TR Yes C26 1 Capacitor, Ceramic, X7R 22 nF, 50 V 10% SMD, 0603 TDK C1608X7R1H223K Yes C27 1 Capacitor, Ceramic, X7R 10 nF, 50 V 10% SMD, 0603 Murata GRM188R71H103KA01D Yes C28 1 Capacitor, Electrolytic 100 mF, 35 V 20% Through Hole, 2.5 mm Kemet ESH107M035AE3AA Yes C29 0 Capacitor, Ceramic, X7R PLACEHOLDER SMD, 0603 PLACEHOLDER PLACEHOLDER Yes C30 1 Capacitor, Ceramic, X5R 10 mF, 35 V SMD, 1206 Taiyo Yuden GMK316BJ106KL−T Yes C31 0 Capacitor, Ceramic, X7R PLACEHOLDER SMD, 0603 PLACEHOLDER PLACEHOLDER Yes C32 1 Capacitor, Ceramic, COG 33 pF, 50 V 5% SMD, 0603 Murata GRM1885C1H330JA01D Yes CX1, CX2 2 Capacitor, Metallized Polypropylene 100 nF, 275 VAC 10% Through Hole, 10 mm Kemet PHE840MA6100KA04 Yes CY1, CY2, CY3 3 Capacitor, Ceramic, X1Y2 1000 pF, 250 VAC 20% Through Hole, 5 mm Murata DE2E3KY102MA2BM01 Yes D1, D2 2 Diode, Standard Recovery 1000 V, 1 A SMD, SMA ON Semiconductor MRA4007T3G Yes D3 1 Diode, Standard Recovery 600 V, 3 A Through Hole, Axial, DO−201AA ON Semiconductor 1N5406G No 10% http://onsemi.com 9 DN05044/D Table 3. BILL OF MATERIALS FOR 20 W NCP1126/1129 FLYBACK (continued) REF DES Qty. Description Value Footprint Manufacturer Manufacturer PN Substitution D4 1 Diode, Switchmode Rectifier 520 V, 5 A Through Hole, Axial, DO−201AA ON Semiconductor MUR550APFG No D5, D6, D8, D9, D10, D11, D19 7 Diode, Switching 100 V, 200 mA SMD, SOD−123 ON Semiconductor MMSD4148T1G Yes D7 1 Diode, Standard Recovery 1000 V, 1.5 A SMD, SMB Vishay S2M-E3/52T No D12, D13, D18 3 Diode, Switching 250 V, 100 mA SMD, SOD−123 ON Semiconductor MMSD103T1G Yes D14 1 Diode, Zener 27 V, 500 mW SMD, SOD−123 ON Semiconductor MMSZ5254BT1G Yes D15 1 Diode, Schottky, 100 V, 5 A SMD, SO−8FL ON Semiconductor MBR5H100MFST1G No D16 1 Diode, Bridge Rectifier 600 V, 4 A Through Hole, GBU Diodes Inc GBU406 Yes D17 1 Diode, Zener 7.5 V, 500 mW SMD, SOD−123 ON Semiconductor MMSZ5236BT1G Yes F1 1 Fuse 250 VAC, 3 A Through Hole Littelfuse 0224003.HXP No J1 1 Terminal Block, 3 pos, in-line 250 V, 16 A Through Hole, 5mm On Shore Technology OSTTA030161 Yes J2 1 Header, 2 pos, in-line, right angle 250 V, 12 A Through Hole, 5mm Phoenix Contact 1757475 Yes J2A 1 Terminal Block, 2 pos, plug 250 V, 12 A N/A Phoenix Contact 1754449 Yes L1 1 Inductor, Common mode choke 4 mH, 1.5 A Through Hole Wurth Electronics 744 821 240 No L2 1 Inductor, Common mode choke 20 mH, 0.5 A Through Hole Wurth Electronics 744 822 120 No L3 1 Inductor, Differential choke 300 mH, 2 A Through Hole Wurth Electronics 744 706 0 No L4 1 Inductor, PFC boost 390 mH, 3.5 A Through Hole, RM10, Custom Wurth Electronics 750313048 rev2 No M1 1 MOSFET, PFC Switch 600 V, 12 A TO−220FP Toshiba TK12A60U No M2 1 MOSFET, QR Switch 650 V, 10.6 A TO−220FP Infineon IPA65R380C6 No M3 1 MOSFET, Synchronous Rectifier 100 V, 100 A TO−220 Infineon IPP045N10N3 No MOV1 1 MOV 300 VAC, 2.5 kA Through Hole, 10 mm Epcos S10K300 Yes Q1 1 MOSFET, Small signal PMOS, 50 V SMD, SOT23−3 ON Semiconductor BSS84LT1G Yes R1, R2 2 Resistor, 1/4 W 1 kW SMD, 1206 Stackpole RMCF1206FT1K00 Yes R3, R3A, R3B, R3C 4 Resistor, 1/2 W 0.5 W SMD, 1206 Stackpole CSR1206FKR500 Yes R4, R12, R51 3 Resistor 1/10 W 10 kW 1% SMD, 0603 Stackpole RMCF0603FT10K0 Yes R5 1 Resistor, 1/4 W 8.06 kW 1% SMD, 1206 Stackpole RMCF1206FT8K06 Yes R6 1 Resistor 1/10 W 8.06 kW 1% SMD, 0603 Stackpole RMCF0603FT8K06 Yes R7 1 Resistor, 1/8 W 47.5 W 1% SMD, 0805 Stackpole RMCF0805FT47R5 Yes R8 1 Resistor, 1/8 W 4.75 W 1% SMD, 0805 Stackpole RMCF0805FT4R75 Yes R9 1 Resistor, 1/8 W 20 W 1% SMD, 0805 Stackpole RMCF0805FT20R0 Yes R10, R28, R49 3 Resistor, 1/4 W 20 W 1% SMD, 1206 Stackpole RMCF1206FT20R0 Yes R11 1 Resistor, 1/4 W 8.25 W 1% SMD, 1206 Yageo RC1206FR-078R25L Yes REF DES QTY Description Value Tolerance Footprint Manufacturer Manufacturer PN Substit ution Tolerance 1% http://onsemi.com 10 DN05044/D Table 3. BILL OF MATERIALS FOR 20 W NCP1126/1129 FLYBACK (continued) REF DES Qty. Description Value Tolerance Footprint Manufacturer Manufacturer PN Substitution R13, R13A 2 Resistor, 1 W 0.4 W 1% SMD, 2512 Yageo PT2512FK−070R4L No R14 1 Resistor, 1/10 W 249 W 1% SMD, 0603 Stackpole RMCF0603FT249R Yes R15, R16 2 Resistor, 1/4 W 1.62 MW 1% SMD, 1206 Yageo RC1206FR-071M62L Yes R17 1 Resistor, 1/8 W 118 kW 1% SMD, 0805 Stackpole RMCF0805FT118K Yes R18 1 Resistor, 1/10 W 34 kW 1% SMD, 0603 Stackpole RMCF0603FT34K0 Yes R19 1 Resistor, 1/10 W 20 kW 1% SMD, 0603 Stackpole RMCF0603FT20K0 Yes R20 1 Resistor, 1/10 W 499 kW 1% SMD, 0603 Stackpole RMCF0603FT499K Yes R21, R31 2 Resistor, 1/10 W 0W SMD, 0603 Yageo RC0603JR−070RL Yes R22 1 Resistor, 1/4 W 5.11 MW 1% SMD, 1206 Yageo RC1206FR−075M11L Yes R23 1 Resistor, 1/10 W 750 kW 1% SMD, 0603 Stackpole RMCF0603FT750K Yes R24 1 Resistor, 1/10 W 80.6 kW 1% SMD, 0603 Stackpole RMCF0603FT80K6 Yes R25, R27 2 Resistor, 1/8 W 2 kW 1% SMD, 0805 Stackpole RMCF0805FT2K00 Yes R26 1 Resistor, 1/8 W 1 MW 1% SMD, 0805 Stackpole RMCF0805FT1M00 Yes R29, R30 2 Resistor, 1/10 W 15 kW 1% SMD, 0603 Stackpole RMCF0603FT15K0 Yes R32 1 Resistor, 1/10 W 267 W 1% SMD, 0603 Yageo RC0603FR−07267RL Yes R33 1 Resistor, 1/10 W 453 kW 1% SMD, 0603 Stackpole RMCF0603FT453K Yes R34 1 Resistor, 1/10 W 90.9 kW 1% SMD, 0603 Stackpole RMCF0603FT90K9 Yes R35 1 Resistor, 1/10 W 200 kW 1% SMD, 0603 Stackpole RMCF0603FT200K Yes R36, R37 2 Resistor, 1/10 W 14.3 kW 1% SMD, 0603 Stackpole RMCF0603FT14K3 Yes R38 1 Resistor, 1/10 W 2.32 kW 1% SMD, 0603 Stackpole RMCF0603FT2K32 Yes R39 1 Resistor, 1/10 W 1 kW 1% SMD, 0603 Yageo RC0603FR−071KL Yes R40 1 Resistor, 1/4 W 0W SMD, 1206 Yageo RC1206JR−070RL Yes R41 1 Resistor, 1/10 W 10 W 1% SMD, 0603 Stackpole RMCF0603FT10R0 Yes R42, R43, R44, R45 4 Resistor, 1/4 W 100 kW 1% SMD, 1206 Stackpole RMCF1206FT100K Yes R50 1 Resistor, 1/8W 10 kW 5% Through Hole Stackpole CF18JT10K0 Yes R52 0 Resistor 1/10 W PLACEHOLDER SMD, 0603 PLACEHOLDER PLACEHOLDER Yes R53 1 Resistor 1/10 W 35.7 kW 1% SMD, 0603 Stackpole RMCF0603FT35K7 Yes RT1 1 NTC Thermistor 220 K, 500 mW 5% Through Hole, 2.54 mm Vishay NTCLE100E3224JB0 No RT2 1 NTC Inrush Current Limiter 15 W Through Hole, 10 mm Epcos B57153S0150M000 Yes TX1 1 Flyback Transformer 500 mH, 4 A Through Hole, PQ32, Custom Wurth Electronics 750313054 rev02 No U1 1 Controller, PFC - QR Combo SMD, SOIC−20NB, 1 mm ON Semiconductor NCP1937A No U2 1 Optocoupler 120 V, 60 mA Through Hole, PDIP4 NEC PS2513−1−A No U3 1 Optocoupler 70 V, 30 mA Through Hole, PDIP4 NEC PS2561A−1 Yes U4 1 Controller, Secondary side SOIC−8 ON Semiconductor NCP4355B No U5 1 Synchronous rectification driver SOIC−8 ON Semiconductor NCP4304A No http://onsemi.com 11 DN05044/D DEMO BOARD http://onsemi.com 12 DN05044/D REFERENCES [1] Data Sheet NCP1937/D [2] Data Sheet NCP4355/D [3] Data Sheet NCP4304/D ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). 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