DN06021/D Design Note – DN06021/D 16 W, 12 Vdc Modem Power Supply Device Application Input Voltage Output Power Topology I/O Isolation NCP1027 AC-DC adapter for modem, hub, router 90 to 264 Vac 16 W DCM Flyback Yes – 3 kV Other Specifications Output Voltage Ripple Nominal Current Max Current Min Current Output 1 Output 2 Output 3 Output 4 12 V +/- 5% 1% max (120 mV) 1.3 A 1.5 A (10 sec) zero N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A No 76.4% at 120 Vac; 78% at 230 Vac averaged over 25%, 50%, 75% and 100% of the load 8 ohm resistor + 1 A fuse 0 to +45°C Convection PFC (Yes/No) Average Efficiency Inrush Limiting / Fuse Operating Temperature Range Cooling Method/Supply Orientation Others Total regulation (line and load): better than 2% Circuit Description Key Features This design note presents a simple yet feature loaded 16 watt output, universal AC input adapter power supply for modems, hubs or similar applications. The circuit is a discontinuous mode (DCM) flyback converter topology designed around ON Semiconductor’s NCP1027 monolithic current mode controller with internal 700V Mosfet. The output will provide up to 1.5 amps peak and will regulate at full output as low as 85 Vac input. The supply also includes an EMI input filter as well as adjustable brown-out and power limit features. A very simple zener diode and optocoupler feedback scheme is used that provides good output regulation with a minimum of components. The schematic of an optional resonant snubber is also shown which will improve the efficiency an additional two percentage points over the standard RCD snubber for the 120 Vac input range (see figure 2 and plots). y Simple, low cost, yet highly effective power supply circuit y Over-current, over-voltage and over- temperature protection y Efficiency and no-load (standby) parameters meet Energy Star requirements (see data below) y Small and simple flyback transformer construction for easy mass production y Optional resonant snubber for even higher efficiency January 2007, Rev. 0 www.onsemi.com 1 DN06021/D Figure 1. Schematic for the 16 W, 12 V AC-DC modem adapter L1 3.9 mH R1 8.2, 2W AC input F1 C1 10 nF "x" 1 A, 250 Vac D1-D4 1N4007 T1 C2 100 nF "x" R2 4.7 10 uF, 400Vdc x2 C3 C5 180pF 2 kV C4 L2 680 uH D6 MBRS360T 10 R3 39K, 1W 1 5 9 6 D5 MURS160 R4 100K C12 + 12V @ 1.3A 0.1 C7 C6 _ 470 uF 16V x2 2 MMSD1N4148A R14 omit R11 2.2M R13 omit R15 10 NCP1027 (100 kHz) C11 1 nF 3 8 Z1 MMSZ5241B (11V) C13 C10 10 uF 25V 2.2nF "Y2" R5 Vtrim (0 ohm) R9 1K 5 3 R10 30K D7 + R12 2.2M R6 U1 2 4 4 7 1 8 R8 0 ohm U2 47 1 R7 330 C8 + C9 1 nF 10 uF 25V 3 opto 2 NOTES: 1. L1 is Coilcraft E3491-AL common mode EMI inductor (3.9 mH) 2. L2 is Coilcraft part RFB0810-681L or similar (680 uH, 500 mA) 3. See Magnetics Data Sheet for T1 construction details. 4. R9 sets OVP trip level. 5. R8, R13, R14 for optional power limit feature (see NCP1027 data sheet.) 6. Z1 zener sets Vout: Vout = Vz + 0.85V; R5 is optional voltage trim resistor 7. R10 sets AC input brownout level. 8. R1 is optional inrush limiter. 9. U1 requires Aavid #580100W00000G clip-on DIP8 heatsink or similar. 10. Crossed schematic lines are not connected Snubber Figure 2 shows an alternative to the classical RCD snubber network, using a non-dissipative resonant snubber. This resonant snubber not only recycles the leakage energy to the input bulk capacitor C4, but also provides more effective shaping of the Mosfet’s load line, thus lowering switching losses. At Mosfet turn-off, the leakage inductance energy of T1 is transferred to Cr and the rate of rise of the drain voltage (dV/dt) is slowed. When the Mosfet turns back on the capacitor is discharged by transferring its energy to Lr in the resonant circuit formed by LR/Cr. During the next offperiod the energy is then transferred back to the bulk cap through the series diodes. This action can actually be best interpreted as a resonant “charge pump” in which the leakage inductance energy is returned to the bulk cap. The additional component cost includes the small inductor Lr and another ultrafast diode. The overall converter circuit efficiency improvement should be several percentage points, particularly at light loads. January 2007, Rev. 0 Figure 2. Non dissipative resonant snubber option T1 10 10 uF, 400Vdc x2 C3 www.onsemi.com C4 MURS160 x2 Lr = 1.5 mH L2 680 uH Bulk common Lr is Coilcraft RFB0810-152L 1 Cr 180pF 2 kV 9 2 Drain terminal 2 DN06021/D MAGNETICS DESIGN DATA SHEET Project / Customer: ON Semiconductor - 16 - 18 watt, 12 vout adapter supply Part Description: 18 watt NCP1027 flyback transformer, 100 kHz, 12V / 1.5 A (Rev 1) Schematic ID: T1 Core Type: E24/25 (E25/10/6); 3C90 material or similar Core Gap: Gap for 750 to 800 uH across pins 2 and 10 with pins 1 and 9 connected Inductance: 775 uH +/-5% (across pins 2 and 10 with pins 1 and 9 connected) Bobbin Type: 10 pin horizontal mount for E24/25 (E25/10/6) Windings (in order): Winding # / type Turns / Material / Gauge / Insulation Data Primary A (1 - 10) 25 turns of #30HN over 1 layer. Insulate for 1 kV to next winding. Self leads to pins.. Vcc (3 - 8) 5 turns of #30 HN spiral wound over 1 layer with 3 mm end margins minimum. Self leads to pins. Insulate to 3 kV to next winding 12V Secondary (5 - 6) 5 turns of three strands of #26HN (trifilar) over previous winding with 1.5 mm end margins approximately. Winding ends should be cuffed with tape to avoid edge breakdown other windings. Insulate for 3 kV to next winding. Self leads to pins. Primary B (2 - 9) Same as Primary A. Hipot: 3 kV from primaries & Vcc to secondary for 1 minute. Lead Breakout / Pinout Schematic (Top View) 10 10 9 8 7 6 1 Vendor: Mesa Power Systems, Escondido, CA. 760-489-8162 Part # 13-1302 5 9 2 3 6 12 3 4 5 8 January 2007, Rev. 0 www.onsemi.com 3 DN06021/D Results Efficiency Traditional RCD snubber Efficiency @ 25C 230 Vac 73 78.2 80 80.6 78.0% 74% % Load 120 Vac 230 Vac 25 76.2 74.4 50 79 79.8 75 79 80.5 100 78.2 81 Average efficiency Minimum efficiency per ENERGY STAR: [0.09 * Ln(16W)] + 0.49 78.1% 78.9% 74% 74% 90 90 80 80 Efficiency (%) Efficiency (%) Efficiency @ 25C % Load 120 Vac 25 74 50 77 75 77.6 100 76.8 Average efficiency 76.4% Minimum efficiency per ENERGY STAR: 74% [0.09 * Ln(16W)] + 0.49 Non-Dissipative resonant snubber 70 60 70 60 50 50 0 10 20 30 40 50 60 70 80 90 100 % Load 120 Vac 0 10 20 30 40 50 60 70 80 90 100 % Load 230 Vac 120 Vac 230 Vac No load input power Traditional RCD snubber 290 mW @ 120 Vac 210 mW @ 240 Vac Non-Dissipative resonant snubber 240 mW @ 120 Vac 200 mW @ 240 Vac Line Regulation: < 0.5% Load Regulation: 2% AC mains dropout voltage with full load: 84 Vac Vout ripple (p/p):120 mV January 2007, Rev. 0 www.onsemi.com 4 DN06021/D Bill of Materials 16W, NCP10127 Adaptor BOM (Rev. 4) Part Qty ID Description Comments ON Semi ON Semi ON Semi ON Semi Vishay ON Semi Vishay Vishay Vishay Vishay Vishay UCC, Rubycon UCC, Rubycon UCC, Rubycon Ohmite Ohmite Ohmite MRA4007 MURS160 MBRS360T Schottky MMSZ5241B zener diode Optocoupler, SFH6156A-4 (4 pin) NCP1027 (100 kHz) "X" cap, disc type "Y" cap, disc type Ceramic cap, disc Ceramic cap, monolythic Ceramic cap, monolythic Electrolytic cap Electrolytic cap Electrolytic cap Resistor, 2W Resistor, 1W Resistor, 1/4W 4 1 1 1 1 1 2 1 1 1 2 2 2 2 1 1 1 D1 - D4 D5 D6 Z1 U2 U1 C1, C2 C13 C5 C12 C8, C11 C3, C4 C6, C7 C9, C10 R1 R3 R2 Resistor, 1/4W Resistor, 1/8W Resistor, 1/8W Resistor, 1/4W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/8W Resistor, 1/4W Resistor, 1/4W Heatsink for U1 Inductor, 680 uH EMI Inductor, 3.9 mH 1 1 1 1 1 1 1 1 2 2 1 1 1 R8 R7 R6 R4 R5 R15 R9 R10 R11, R12 R13, R14 L2 L1 1A, 800V diode 1A, 600V UFR diode 3A, 60V Schottky 11V, 250 mW zener Optocoupler 100 kHz current mode controller 10 nF "X2" capacitor, 250 Vac 2.2 nF, "Y2" capacitor, 250 Vac 4.7 nF, 2 kV capacitor (snubber) 0.1 uF, 50V ceramic cap 1 nF, 50V ceramic cap 10 uf, 400Vdc 470 uf, 16 V (low ESR) 10uf, 25V 8.2 ohm, 2W ceramic 39K, 1W 4.7 ohm, 1/4W 0 ohms, 1/4 W (jumper - power limit) 330, 1/8 W 47 ohms, 1/8 W 100K, 1/4W 0 ohms, 1/8 W (jumper) 10 ohms 1K ohms 30K 2.2Meg TBD (optional for power limit) Aavid 580100W00000G RFB0810-681L E3491-AL Transformer 1 T1 Flyback Xfmr #13-1302 Ohmite Ohmite Ohmite Ohmite Ohmite Ohmite Ohmite Ohmite Ohmite Ohmite Aavid Coilcraft Coilcraft Mesa Power Systems 1 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. 0 www.onsemi.com 5