DN06045/D Design Note – DN06045/D Triple, Low Voltage Output, Off-Line Power Supply Device Application Input Voltage Output Power Topology I/O Isolation NCP1014, NCP3120 Appliances & Consumer Electronics 90 to 265 Vac 10 Watts Peak DCM Flyback Yes – 3 kV Other Specification Output Voltage Ripple Nominal Current Max Current Min Current Output 1 Output 2 Output 3 Output 4 5.0 Volts 50 mV User dependent 1.5 A Zero 3.3 Volts 50 mV User dependent 2A Zero 1.8 Volts 50 mV User dependent 2A Zero N/A N/A N/A N/A N/A PFC (Yes/No) Minimum Efficiency Inrush Limiting / Fuse Operating Temp. Range Cooling Method / Supply Orientation Signal Level Control No 70% (load combination dependent) Yes 0 to +50°C Convection Yes, outputs on/off, output sequencing Circuit Description This Design Note presents an off-line, triple, low voltage output power supply intended for appliance and/or consumer electronic products that require a maximum power of 10 watts or less such as set-top boxes, modems, and similar. The efficiency is characterized below for a nominal output of 6 watts for several different load configurations. The design is intended to meet the latest Energy Star efficiency requirements for the typical steady state loads represented in the tests. The selected output voltages can easily be tailored to suit most applications but are considered representative of typical low voltage requirements for most microprocessors and their associated interface circuitry. The power supply is configured around a discontinuous mode (DCM) flyback converter utilizing the NCP1014 monolithic switching controller/Mosfet (U1). Synchronous rectification is used on the primary 5 volt output and the NCP3120 dual, monolithic buck converter (U3) is used for the 3.3 and 1.8 volt outputs with the input power derived from the 5 volt rail. It should be noted that DCM flyback transformer operation is necessary over the entire load range to allow proper operation of the 5 V synchronous rectifier circuit associated with Q3. July 2008, Rev. 0 Output regulation is accomplished for the 5 V output using the conventional TL431 and optocoupler feedback scheme. Current limiting for the 5 V output is accomplished via peak primary current detection in U1 while current limiting and regulation functions for the 3.3 V and 1.8 V outputs are handled by the internal circuitry of U3. An on/off function for the 5 V output is provided by Q2 and can be provided for the other outputs via control pins on U3 even though it is not implemented in this design example. Startup and shutdown output sequencing are also available with the NCP3120. Key Features y Conducted EMI filter for ac input. y Transformer aux bias supply for low standby power. y On/off control and start/stop sequencing available on all outputs. y Energy Star compliant for most typical load configurations. y Very inexpensive yet efficient dual buck regulator for 1.8 and 3.3 V outputs. y Synchronous rectifier for main 5 V output. www.onsemi.com 1 DN06045/D Schematic 0.1 R2 "X" 0.1 "X" R1 4.7, 2W 1M 0.5W 5,6 D5 1N4007 C3 47uF 400V 1 Gnd 3 U1 2 C9 1nF 1N4148A 3 + C8 2.2 nF "Y" FB C7 + Q6 R6 1K 2 10uF, 25V Vcc Q5 D6 R3 3.3K 1 4 R5 C6 22uf 25V Q2 2N2222 2N2222 Q4 100 D7 D 1 2 1K C4 270pF 4 2kV NCP1014 SOT-223 (65 kHz) 0.1 COM R4 1N4148A C5 5V C12 1:50 R20 47 R21 82K 0.5W 10 Watt, 3 output DTA Set Top Box Supply Q3 T2 4 U2 1 2N2222 C2 C11 470uF 6.3V 2N2907 C1 D1 - D4 1N4007 8 Q1 R8 C10 1,500uF 6.3V 7,8 L1 90265 Vac L2 4.7uH T1 100K F1 1A 100K 5Vout on/off R9 20K R7 20K R11 R12 1K 180 R13 10K 1 nF R14 4.99K C13 0.1 2 3 7 R10 U5 TL431A R15 4.75K 4 470 R22 L3 19 17 18 2 3 4 5 6 7 20 21 U3 22 NCP3120 13 R23 Notes: 10 C22 0.1 R25 15K R26 15K plate 16 C21 0.1 R24 C20 C19 0.1 12 29 25 MBRS D8 320T 23 NC + C18 28 470K 1. Crossed lines on schematic are not connected. 2. U2 is Vishay H11A817A optocoupler or equivalent. 3. L1 is Coilcraft BU16-4530R5BL or similar CM EMI inductor. 4. L3 and L4 are Coilcraft DO3316P-153L or similar (15 uH, 3A). 5. L2 is Coilcraft RFB0807-4R7L or similar (4.7 uH, 4A). 6. Q1 is ON Semi NTD25P03LG P-channel Mosfet. 7. Q3 is ON Semi NTB30N06LT4G N-ch logic level Mosfet (D2Pak) 8. T2 is Coilcraft current sense xfmr T6522-AL (Np/Ns = 1:50) or similar. 9. C18 should be low impedance ceramic cap. 10. U3 will require proper DFN package heatsinking to pcb clad. 11. For activation of 5V output On/Off input must be a logic level "1". 12. Recommended ground plane areas shown in heavy lines. 13. U3 output inhibit and sequencing functions not used in this example (see NCP3120 data sheet for details). 14 27 0.1 11 30 3 3.3V 15uH 32 31 1 26 R16 31K + R17 10K C15 0.1 C14 4.7, L4 1500uF 24 NC 16V 15uH 6.3V x 2 8 C16 9 MBRS R18 10 + D9 320T 12.5K 15 R19 10K 5 6 1.8V C17 0.1 signal gnd power gnd Additional collateral from ON Semiconductor y Data sheet NCP1014: Self-Supply Monolithic Switcher for Low Standby-Power Offline SMPS y Data sheet NCP3120: Dual 2.0 A Switching Regulator (200-750 kHz) y Design Note DN06003: NCP1014, 8 W, 3-Output Off-Line Switcher y Design Note DN06005: NCP1014, 10 W, 3-Output Off-line Power Supply y Design Note DN06020: NCP1014, 10W, Dual Output Power Supply y Design Note DN06034: NCP1014, Universal Input, +/- 12 V Output, 8 Watt Power Supply y Reference Design TND332: 8 W DTA Power Supply GreenPoint™ Reference Design y Reference Design TND329: 5 W CCCV AC-DC Adapter GreenPoint™ Reference Design July 2008, Rev. 0 www.onsemi.com 2 DN06045/D Test Results Efficiency versus Output Loading Configuration (Total load = 6 Watts approximately): Configuration 1 2 3 4 5V out 0.25 A 0.5 A 0.3 A 1A 3.3 Vout 0.35 A 0.5 A 1A 0.15 A 1.8 Vout 2A 1A 0.75 A 0.3 A Eff. @ 120 Vac 65% 76% 72% 78% Eff. @230 Vac 64% 75% 71% 77% ENERGY STAR minimum efficiency requirement for 6 W output = 70.4% (satisfied by Configuration 2, 3, 4) Standby (no load) power consumption: @ 120 Vac input: 90 mW @ 230 Vac input: 240 mW Line and load regulation: Better than 1% on all outputs. Output Ripple Profiles: 5Vout @ 1 A and 1.8 Vout @ 1.2 A. 5 Vout @ 1 A July 2008, Rev. 0 1.8 Vout @ 1.2 A www.onsemi.com 3 DN06045/D MAGNETICS DESIGN DATA SHEET Project / Customer: ON Semiconductor - STB power supply - 10 watts max. Part Description: 10 watt flyback xfmr, 65 kHz/5Vout Schematic ID: T1 Core Type: EF16 (E16/8/5); 3C90 material (Ferroxcube) or similar Core Gap: Gap for 1.5 mH inductance Inductance: 1.5 mH +/-10% Bobbin Type: 8 pin horizontal mount for EF16 Windings (in order): Winding # / type Turns / Material / Gauge / Insulation Data Vcc/Boost (3 - 2) 12 turns of #34HN spiral wound over 1 layer. Insulate with 1 layer of tape (1000V insulation to next winding) Primary (4 - 1) 90 turns of #34HN over 2 layers (45 turns/layer); Insulate for 3 kV to the next winding with tape. 5V Secondary (7,8 - 5,6) 6 turns of 2 strands of #26HN wound bifilar over one layer with 2 mm end margins and cuffed ends. Self leads to pins as shown below. Insulate with final layer of tape. Vacuum varnish assembly Hipot: 3 kV from boost/primary to secondary Lead Breakout / Pinout Schematic (Bottom View - facing pins) 1 8 7 4 4 6 5 3 2 1 5 6 7 8 3 2 July 2008, Rev. 0 www.onsemi.com 4 DN06045/D 1 Bill of Materials Part ID Description Com m ents 5 2 2 3 1 1 1 1 2 1 1 D1, 2, 3, 4, 5 D6, D7 D8, D9 Q2, 4, 5 Q6 U1 Q1 Q3 U3 U2 U5 1A, 800V diode 100 mA signal diode 3A, 20V Schottky diode 500 mA, 40V NPN xstr 500 mA, 40V PNP xstr Monolythic PWM controller - 65 kHz P-channel Mosfet, 30V N-channel Mosfet, logic level Dual buck regulator SFH6156A-4 (4 pin) or similar Programmable zener ON Semi ON Semi ON Semi ON Semi ON Semi ON Semi ON Semi ON Semi ON Semi Vishay ON Semi Capacitors "X" cap, (box package) "Y" cap, disc package Ceramic cap, disc Ceramic cap, monolythic 2 1 1 8 100 nF "X2" capacitor, 270 Vac 2.2 nF "Y2" cap, 270 Vac 270 pF, 2 kV capacitor (snubber) 0.1 uF, 50V ceramic cap Vishay Vishay Vishay Vishay Ceramic cap, monolythic Ceramic cap, monolythic Ceramic cap, monolythic Electrolytic cap Electrolytic cap Electrolytic cap Electrolytic cap Electrolytic cap 2 1 2 1 1 3 1 1 C1, C2 C8 C4 C12, 13, 15, 17, 19, 20, 21, 22 C14, C16 C18 C7, C9 C11 C3 C10, C14, 16 C5 C6 2.2 uF, 16V low impedance ceramic 4.7 uF, 16V, multilayer 1 nF, 50V ceramic cap 470 uF, 6.3V 47 uF, 400Vdc 1500 uF, 6.3 V (low ESR) 10uF, 25V 22 uF, 25V Vishay Vishay Vishay UCC, Rubycon UCC, Rubycon UCC, Rubycon UCC, Rubycon UCC, Rubycon Resistors Resistor, 2W Resistor, 1/2W Resistor, 1/4W Resistor, 1/4W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor,1/8W Resistor,1/8W Resistor,1/8W Resistor,1/8W Resistor, 1/8W 1 1 1 1 2 1 1 1 1 2 3 1 1 1 1 1 1 1 2 1 R1 R2 R4 R21 R6, R12 R5 R3 R7, R9 R11 R8, R10 R13, 17, 19 R14 R15 R16 R20 R22 R23 R24 R25, R26 R18 4.7 ohm, 2W ceramic, axial lead 1 Meg, 1/2W, axial lead, metal film 1K 82K 1K 100 ohms 3.3K 20K 180 ohms 100K 10K 4.99K 4.75K 31K 47 ohms 470 ohms 10 ohms 470K 15K 12.5K Ohmite Ohmite 5% SMD (1206) 5% SMD (1210) 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD 1% SMD Miscellaneous Fuse (TR5 type) 1 F1 1 to 1.5A, 250 Vac Bussmann Magnetics EMI Inductor Choke, 4.7 uH, 4A Choke, 15 uH, 3 A Flyback Transformer (custom) Current sense transformer (1:50) 1 1 2 1 1 L1 L2 L3, L4 T1 T2 BU16-4530R5BL (or similar) RFB0807-4R7L (or similar) DO3316P-153L (15 uH, 3A) Coilcraft Coilcraft Coilcraft See draw ing Coilcraft Sem iconductors MRA4007T3G MMSD4148T1 MBRS320T MMBT2222AWT1 MMBT2907AWT1 NCP1014ST65T3G NTD25P03LG NTB30N06LT4G NCP3120MNTXG Optocoupler TL431ACD (SOIC-8) Qty T6522-AL (or equivalent) 1 © 2008 ON Semiconductor. Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its products at any time, without notice. Design note created by Frank Cathell, e-mail: [email protected] July 2008, Rev. 0 www.onsemi.com 5