DN06029/D Design Note – DN06029/D Universal Input, 50W, 5 Output PSU Device NCP1308, LM2575 Application Input Voltage Medical Equipment 85 to 265 Vac Output Power Topology I/O Isolation 40 W average, 50 W peak QuasiResonant Mode Flyback Yes – 3kV Other Specifications Output Voltage Ripple Nominal Current Max Current Min Current Output 1 Output 2 Output 3 Output 4 12 VDC +/- 20mV 2.5 A 3A 10 mA -12 VDC +/- 20mV 150 mA 300 mA 10 mA 5 VDC 2% - 5% 900 mA 1.2 A 10 mA 3.3 VDC 2% - 5% 150 mA 300 mA 10 mA PFC (Yes/No) No Minimum Efficiency 75 % at nominal load Inrush Limiting / Fuse Yes - both Operating Temp. Range Cooling Method/Supply Orientation 0 to +60°C Others Convection 5th Output with 350 Vdc @ +/- 20 V at 50 mA max. Circuit Description Key Features This Design Note features a universal AC input, 50 watt peak output flyback power supply with 5 separate output voltages. The 3.3 volt and 5 volt outputs are derived from the +12 volt output using identical LM2575 monolithic buck regulators. The 350 volt output is derived from a “slave” secondary flyback winding on the main transformer. ON Semiconductor’s NCP1308 controller provides for quasi-resonant Mosfet switching and current mode control of the flyback topology for high conversion efficiency and low noise generation. Voltage sensing and regulation for the main +12 volt output is achieved utilizing the conventional TL431A error amp and optocoupler feedback scheme. The negative 12 volt output achieves satisfactory regulation via a tightly coupled secondary winding with the main +12 V output’s secondary winding (bifilar wound). The 3.3 V and 5 V outputs require minimal components utilizing the LM2575 buck regulators and off-the-shelf ferrite inductors. y July 2007, Rev. 1 Over-current, over-voltage, and over-temperature protection. y Input common and differential mode EMI filter for agency EMI compliance. y NTC thermistor for inrush current limiting at initial supply turn-on. y Pi-network ripple filters (L2, L3) on the +/-12 V outputs for low output noise and ripple. y Main flyback transformer designed with common industry standard ETD29 ferrite core. www.onsemi.com 1 DN06029/D Schematic 2A F1 250Vac AC Input C2 TH1 C5 180uF 400V C3 C4 10 ohm 2.0A 2.2nF 1kV 1N4007 Q1 R5 2.2 R6 10K 0.5W 1nF x 2 "Y2" 6 R4 10K R3 0.4 ohms 0.5W D9 8 D6 6 2 4 3 C7 1nF R8 1N4148 68K R9 470 C8 C9 22uF 100pF 16V 100 12 8 2 5 3 3 5 L4A & B 390uH D11A, B 1N5817 L3 +12V 0.1 Com C20 220uF 25V C22 C21 0.1 -12V 0.1uF 50V U2 1 2 750 R13 1K C10 R14 0.1 R15 9.1K 10K R16 2.4K NOTES: Out C24A, B 470uF 6.3V Gnd Buck Regulator Notes: 1. U4B requires small heatsink (TO-220). 2. C23 should be multilayer ceramic cap and located next to U4. 3. L4 is Coilcraft PCV-0-394-03L or equivalent (390 uH, 3A). July 2007, Rev. 1 R11 5.1K 3.3V C14 0.1 C17 C18 4.7uH U3 TL431A 4 LM2575 -3.3 2 or LM2575 -5 L2 4.7uH 470uF 16V C19 D10 470uF 25V 5V R12 3.3V and 5V Buck Regulator Blocks (A & B) In Gnd MBR1100 4 U4A & B Buck Reg Out C13 0.1 C15 C16 MBR10100 1000uF 4 16V x 2 R7 C12 1nF 1kV 3.3V Regulator Out Block (A) In NCP1308 U1 1 C23 A, B 2.2uF, 16V 5V Regulator Block (B) In 13 D5 9 5 1 350V R10 1M 0.5W C11 10uF, 400V MUR160 x 2 Gnd 1Meg 0.5W Chassis Gnd 7 1 R2 47 1W R1 T Gnd C6 D1 thru D4 1N4007 x4 L1 C1 0.22uF "X2" D7 D8 T1 0.22uF "X2" 1. Crossed lines on schematic are not connected. 2. Heavy lines indicate recommended ground plane area. 3. L1 is Coilcraft BU15-2721R6BL or similar EMI inductor. 4. L2 & L3 are Coilcraft PCV-0-472-05L or equivalent. 5. U2 is Vishay H11A817A or equivalent optocoupler. 6. Q1 is 6A, 650V Mosfet (TO-220). 7. Q1 and D9 will need small stamped heatsinks. 50 Watt, 5 Output Universal Input Power Supply www.onsemi.com 2 DN06029/D 1 MAGNETICS DESIGN DATA SHEET 50W, 5 output power Project : Schneider Electric, 50W,supply 5 Output Power Supply Part Description: Quasi-resonant flyback transformer, 50W, +/-12Vout/350Vout Schematic ID: T1 Core Type: ETD29 (Ferroxcube 3C95 material or equivalent) Core Gap: Gap for 400 uH +/- 5% acros pins 13 to 1 Inductance: 380 to 420 uH nominal across primary (pins 13 to 1) Bobbin Type: ETD 13 pin horizontal pc mount (Ferroxcube PC1-29H) Windings (in order): Winding # / type/pins Turns / Material / Gauge / Insulation Data Aux winding (12 - 2) 5 turns of # 26HN spiral wound evenly over bobbin. Self-leads to pins. Insulate for 1 kV to next winding. Primary (13 - 1) 42 turns of #26HN over one full bobbin layer; Self-leads to pins; insulate for 3 kV to next layer. +/-12V secondary (9,8, - 4,5) 5 turns of 5 strands #25HN; one strand should be green for -12V winding; flat-wind over 1 layer with 3.5 mm approximate end margins. Winding ends should be cuffed with tape. Self-leads to pins with 4 wires per pin on +12 strands. Insulate with tape for 3 kV to next winding. 350V secondary (7 - 6) 135 turns of #38HN over 1 layer; self-leads to pins. Final tape insulation to 3kV. Hipot: 3 kV primary/aux to all secondaries. Vacuum varnish. Schematic Lead Breakout / Pinout 7 1 Pri 13 Aux 12 Bottom (pin side) view 350V 6 9 4 8 2 5 1 2 3 +12V, 4 strands #25 4 5 6 Multifilar Wound -12V, 1 strand #25 green 13 12 11 10 9 8 7 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] July 2007, Rev. 1 www.onsemi.com 3