DN06058/D Design Note – DN06058/D Ultra-Wide Input Range Bias Power Supply Device Application Input Voltage Output Power Topology I/O Isolation NCP1271 Electric Meters, Industrial Applications 40 to 300 Vac 12 watts nominal Flyback Yes – 3 kV Output Output Voltage Ripple Nominal Current Max Current Min Current 12 V 300 mV p/p 1A 1.5 A 0A No 78% @ 40 Vac in 1.5A + inrush resistor -40 to +85˚C Convection PFC (Yes/No) Minimum Efficiency Inrush Limiting / Fuse Operating Temp. Range Cooling Method / Supply Orientation Signal Level Control No Others Operation at 40 Vac input indefinitely Circuit Description This power supply is a 12 volt, 12 watt nominal output, wide range AC input supply designed around the NCP1271 current mode controller in a DCM flyback topology. It is intended for low power logic bias applications (up to 15 watts) in industrial equipment. The circuit includes current limiting, an input EMI filter, a simple resistor (R1) inrush limiter, and optocoupled voltage feedback using a simple TL431 programmable zener error amplifier (U3). The dc bulk input capacitor (C3) is rated to manage continuous operation at 40 Vac input, yet handle the high dc bulk voltage when operated at 300 Vac. An input EMI composed of C1, C2, L1 and C8 is also included. Once the supply has started, an auxiliary winding on the flyback transformer powers the control circuitry to maximize efficiency and to provide minimal power consumption at light or July 2009, Rev. 0 no-load conditions. A Schottky output rectifier (D8) is also used to maximize efficiency. The flyback transformer (see design sheet) is a custom design implemented with a small EF16 type ferrite core. The switching frequency was chosen at 100 kHz to minimize the core size. Key Features y Ultra-wide range AC input (40 to 300Vac) y High efficiency (81% @ 120Vac) y Input EMI filter y Inherent overcurrent protection y Simple current mode flyback design www.onsemi.com 1 DN06058/D Schematic F1 1.5A L1 C1 C2 0.1 R2 "X" 0.1 "X" R1 4.7 ohm, 5W D1 - D4 MRA4007T T1 4 C3 D5 MURS160 100uF 450V 1.5M 0.5W D6 R4 100 0.25W D8 Q1 MMSD 4148T R5 22 5,6 1 D7 MMSD4148T NCP1271 U1 8 5 1 2 0.1 2 3 _ R10 1nF "Y" 1K U2 1 C7 6 C5 100pF C11 12Vout, 1.5A max 1000uF, 16V x 2 4 4 C10 C12 R9 100 1K R7 + MBRS 3200TG3 7,8 C8 R6 3 1K NC 7 R3 100K 0.5W C4 1nF 2kV SPP08N80C3 40 to 300 Vac R8 0.5 1/4W + C6 10uF, 35V 3 U3 TL431A (SOIC8) Notes: R12 18K R11 1K 1nF 1. Crossed lines on schematic are not connected. 2. L1 is Coilcraft part # BU10-1811R2BL or similar EMI filter. 3. Q1 is Infineon SPP08N80C3 or similar (8A, 800V Mosfet) 4. U2 is any opto with a minimum CTR of 50%. (Vishay SFH6156A-4) 5. R12/R13 sets Vout. 6. Heavy schematic lines represent recommended primary and secondary ground plane areas. 7. C1/C2 should be 350Vac minimum voltage rating "X" suppression caps. 8. Max Mosfet current (current limit point) set by R8. 9. C10 and C11 are low Z electrolytic output caps (UCC, Nichicon, etc.) 10. Light load skip mode level set by R7. 2 R14 C9 24K 0.1 R13 4.7K 12Vout, 1A Flyback Schematic 40 - 300 Vac Input July 2009, Rev. 0 www.onsemi.com 2 DN06058/D MAGNETICS DESIGN DATA SHEET Project: Ultra-wide range AC input logic bias power supply; 12V @ 1A output Part Description: 12 watt flyback transformer, 100 kHz, 12 volts out Schematic ID: T1 Core Type: EF16 (E16/8/5); 3C90 material or similar Core Gap: Gap for 125 to 145 uH inductance on primary Inductance: 135 uH +/-5% nominal Bobbin Type: 8 pin horizontal mount for EF16 Windings (in order): Winding # / type Turns / Material / Gauge / Insulation Data Vcc/Boost (2 - 3) 10 turns of #26HN wound over 1 layer. Insulate with 1 layer of tape (500V insulation to next winding) Primary (1 - 4) 40 turns of #26HN over 2 layers. Insulate for 3 kV to the next winding with mylar tape. 12V Secondary (5, 6 - 7, 8) 9 turns of 2 strands of #26 bifilar wound over 1 layer with tape cuffed ends. Self-leads to separate pins as shown below. Vacuum varnish assembly Hipot: 3 kV from Vcc/primary to secondary for 1 minute Lead Breakout / Pinout Schematic (Bottom View - facing pins) 4 5 6 Pri 4 3 2 1 Sec 1 2 7 8 5 6 7 8 Vcc 3 Transformer is Mesa Power Systems part # 13-1410 July 2009, Rev. 0 www.onsemi.com 3 DN06058/D Breadboard Test Data1 • • • • • Vout at 1 A load, 120 Vac in: 12.045 Vdc Vout at 100 mA load, 120 Vac in: 12.053 Vdc Regulation, line and load: Better than 2% Overcurrent trip point: 2.1 A Full load (1A) AC input drop out voltage: 33 Vac (line voltage where output starts to drop out of regulation) • Efficiency with 1 A load: 78% at 40 Vac input; 81% at 120 Vac input; 80% at 240 Vac input Output Ripple: 300 mV peak-to-peak with 1 A load Startup profile into 1 A load at 120 Vac: 1 © 2009 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 F. Cathell, e-mail: [email protected] July 2009, Rev. 0 www.onsemi.com 4