DN06020/D Design Note – DN06020/D 10W, Dual Output Power Supply Device Application Input Voltage Output Power Topology I/O Isolation NCP1014 White goods / Appliance control 90 to 270 Vac 10W peak DCM Flyback Yes Other Specifications Output Voltage Ripple Nominal Current Max Current Min Current Output 1 Output 2 Output 3 Output 4 5 Vdc 2% 350 mA 700 mA 10 µA 14 Vdc 2% 75 mA 500 mA (16 ms) 10 µA N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PFC (Yes/No) No Minimum Efficiency 70% Operating Temp. Range Cooling Method/Supply Orientation 0 to +60 °C Others Convection Tight output cross regulation to +/- 5% Circuit Description Key Features The power supply is designed around the ON Semiconductor NCP1014 monolithic current mode controller with integrated Mosfet in a discontinuous mode (DCM) flyback converter topology. The design includes a pi-network differential mode input EMI filter and resistive turn-on inrush current limiting. The 5 and 14 volt outputs are implemented using a stacked, interleaved secondary winding scheme on the flyback transformer, and summed output sensing through resistors R8 and R9. This sense implementation vastly improves cross regulation between the two outputs. The outputs are sensed, amplified and fed back to the primary controller via the commonly used TL431 and optocoupler circuit scheme. Plots of the minimal cross regulation interaction are shown in the graphs below. Schottky rectifiers are used for output diodes for maximum efficiency. The NCP1014 controller contains inherent over-current and overtemperature protection in addition to over-voltage protection in the event of an optocoupler failure. January 2007, Rev. 1 • Simple, low cost, yet effective dual output off-line switcher design. • Input EMI filter. • Stacked secondary windings and output sense summing for excellent cross regulation. • High efficiency Schottky rectifiers on output. • Auxiliary Vcc winding on transformer for very low standby (no load) input power. www.onsemi.com 1 DN06020/D Schematic R1 L1, 680 uH 9 P D1 1A, 600V 10, 2W C3 10uf, 400Vdc x2 "X2" C4 2.2 nf 2 kV R2 100K, 1W C7 7 Ground Plane U1 3 4 2 R4 680 MMSD4148A 1 D3 C9 0.1 R3 2.2K D4 MBRS140T3G C5 3 5V, 700mA C6 C10 0.1 8 1000uF 6.3V x2 2 4 U2 1 C11 470 pf 3 2 U3 TL-431A NOTES: Com R5 240 1 C12 + 22 uf 16V C8 4 10 NCP1014ST (SOT-223) 14V, 500mA (pk) MBRS1100T3G 6 D2 MURS160 N 330uF, 25V x2 D5 5 C2 C1 Universal AC Input 0.22 uF T1 R6 1K R9 24.5K R8 4.7K C13 R7 68nF 10K R10 2.4K 1. L1 is Coilcraft RFB0807-681L 680 uH, 350 mA inductor. 2. See Magnetics Data Sheet for T1 construction details. 3. U1 is 100 kHz, SOT-223 version of NCP1014 controller. Pin 4 tab should be soldered to copper clad ground plane for best heatsinking. 5. R1 is optional inrush limiter resistor. 6. U2 is Vishay H11A817A optocoupler or equivalent. 7. D1 is Vishay DF06M bridge rectifier (1A, 600V, DIP-4 package) or similar. 8. Output voltage sensing is summed via R8, R9, R10. NCP1014 Based 10W Dual Output Power Supply ON Semiconductor Design Group January 2007, Rev. 1 www.onsemi.com 2 DN06020/D Cross Regulation (measured at 120 Vac input) Cross Regulation: 5 Vout = 700 mA 16 16 14 14 12 12 10 5V out 14V out 8 6 4 Output voltage Output voltage Cross Regulation: 5 Vout = 350 mA 10 6 4 2 2 0 0 0 200 400 5v out 14v out 8 600 0 Current (mA) on 14 Vout 200 400 600 Current (mA) on 14 Vout Line Regulation Less than 20 mV change in any output under any load condition from 90 to 270 Vac. Efficiency 5V@350mA, 14V@75mA – 78% at 120Vac in; 70% at 230Vac 5V@700mA, 14V@500mA – 78% at 120Vac in; 78% at 230Vac No-load Input Power 285 mW @ 230 Vac 216 mW @ 115 Vac January 2007, Rev. 1 www.onsemi.com 3 DN06020/D 1 MAGNETICS DESIGN DATA SHEET Project / Customer: ON Semiconductor - NCP1014 dual output supply Part Description: 10 watt flyback transformer; dual output, universal input Schematic ID: T1 Core Type: E25/10/6 (E24/25); 3C90 material or similar Core Gap: Gap for 1.4 mH Inductance: L= 1.4 mH +/- 5% Bobbin Type: E24-25 PCB1-10 (10 pin horizontal pc mount) Windings (in order): Winding # / type Turns / Material / Gauge / Insulation Data Vcc (1 - 2) 9 turns of #32HN spiral wound over window with 2 mm (approx) end margins. Tape insulate to 1 kV. Selfleads to pins. Primary (10 - 9) 68 turns of #32HN over 2 layers, 34 TPL. Cuff winding ends with tape and insulate for 3 kV to next winding. 5 /14V Secondaries (3 - 8, 4 - 7, 5 - 6) 4 turns trifilar of #26 HN (3 strands, each a different color) with the last turn of one strand removed (for a total of 3 turns with this strand). Allow approx 2.5 mm end margins and terminate leads to pins as shown in diagram below. 3 turn winding should terminate to pins 5 and 6. Insulate with mylar tape. Vacuum varnish assembly. Hipot: 3 kV from 5/14V secondaries to primary/Vcc for 1 minute. Lead Breakout / Pinout Schematic 9 (Top View) 5 3 turns Pirmary 68 turns 10 1 Vcc 9 turns 2 6 4 4 turns 7 3 10 9 8 7 6 Triflar wound minus one turn on top winding 4 turns 12 3 4 5 8 Note: Rectangular hole should be cut in pc board between pins 2 - 3 and 9 - 8 to allow for proper safety spacing on isolated secondary. Proto xfmrs available from Mesa Power Systems, Escondido, CA. 1-800-515-8514 Mesa part number: 13-1298 1 © 2007 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] January 2007, Rev. 1 www.onsemi.com 4