DN06017/D Design Note – DN06017/D Efficient, Low Cost, Low Standby Power (<100 mW), 2.5 W Cell Phone Charger Device Application Input Voltage Output Power Topology I/O Isolation NCP1011 Cell Phone Charger 90 – 270 Vac 2.5 W Flyback Yes Other Specifications Output Voltage Ripple Nominal Current Max Current Min Current Others Output 1 Output 2 Output 3 Output 4 5.0 V (adjustable) 100 mV max 500 mA 620 mA 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 PFC (Yes/No) No Minimum Efficiency 65% Inrush Limiting / Fuse Yes Operating Temp. Range Cooling Method/Supply Orientation Signal Level Control 0 to +50°C Convection No Standby (no load) input power = 90 mW @ 230 Vac Circuit Description Key Features This design note features a very simple, yet highly effective low power cell phone charger designed around ON Semi’s NCP1011 very high voltage switching regulator. The topology is a discontinuous mode flyback with a constant current – constant voltage (CCCV) output profile with better than 100 mA current regulation and 2 % voltage regulation. Plots of the efficiency curves and output current/voltage profile are shown on page 4 of this document. The circuit also includes an input pi filter for conducted EMI compliance. The existing circuit can easily be modified to accommodate other voltage and current combinations and is applicable up to 5 watts output if the NCP1014 is used for U1 with the appropriate rating and/or value changes to C4, D2, D5, R4 and R6. y October 2006, Rev. 1 Constant current – constant voltage output profile suitable Lithium Ion batteries y Over-current, over-voltage and over-temperature protection y Conducted EMI filter y Simple half-wave input rectifier y < 100 mW input standby power when auxiliary winding on transformer used y 90 mW @ 230 Vac y 75 mW @ 120 Vac y Very low cost components y Circuit easily tailored for other voltage/current combinations www.onsemi.com 1 DN06017/D Schematic D1 20, 2W 1N4007 AC input C8 4.7 nF "X" C1 T1 3.5 mH Np/Ns=10:1 1 L1 1 mH 4.7 uF, 400Vdc x2 C5 R2 C2 D2 Ns C9 U1 5.0V, 500 mA _ Charger Output 3 Q1 10 D4 2N2907 D5 (4.3V) R8 R6 2K R5 2 4 4 + 100 nF C7 2 NCP1011ST Is 4 R7 10 uF 25V 3 R4 C4 5,6 MUR160 1N4148 1.2, 1/2W 1000 uF 6.3V Np D3 + MBR150 7,8 150K 1 nF 1 kV 1N5229B R1 1 C6 + C3 10 uF 25V U2 1 1 nF Jumper 100 R3 200 3 opto 2 Notes: 1. D5 and R6 sets Vout (R6 = jumper for 5V; R6 increases voltage) 2. R4 sets Imax (Imax = .65/R4) 3. U1 is SOT223, 100 kHz version of NCP1011 4. L1 is Coilcraft RFB0807-102L (1 mH, 300 mA) 5. U2 is Vishay SFH-615A-4 or similar optocoupler October 2006, Rev. 1 www.onsemi.com NCP1011 CVCC Cell Phone Charger 5.0 Vout, 500 mA 2 DN06017/D MAGNETICS DESIGN DATA SHEET Project / Customer: ON Semiconductor - NCP1011/1014 Generic CP charger Part Description: 5 watt flyback transformer, 4 - 9 volts out (REV 3) Schematic ID: T1 Core Type: EF16 (E16/8/5); 3C90 material or similar Core Gap: Gap for 3.5 mH Inductance: 3.5 mH +/-5% Bobbin Type: 8 pin horizontal mount for EF16 Windings (in order): Winding # / type Turns / Material / Gauge / Insulation Data Vcc/Boost (2 - 3) 28 turns of #35HN spiral wound over 1 layer. Insulate with 1 layer of tape (500V insulation to next winding) Primary (1 - 4) 150 turns of #35HN over 3 layers. Insulate for 3 kV to the next winding. 5V Secondary (5, 6 - 7, 8) 14 turns of #25HN spiral wound over one layer with 0.050" (1.3mm) end margins. Vacuum varinish assembly. Hipot: 3 kV from boost/primary to secondary for 1 minute. Vendor for xfmr: Mesa Power Systems (Escondido, CA) part # 131296 Lead Breakout / Pinout Schematic (Bottom View - facing pins) 1 8 7 4 4 6 5 3 2 1 5 6 7 8 3 2 October 2006, Rev. 1 www.onsemi.com 3 DN06017/D Test Results 1 Results • Configuration: Half-wave input rectifier; no EMI inductor • Transformer Np/Ns: 10:1; Lprimary = 3.5 mH • Vout nominal: 5.065 V • Current limit : 530 mA (Vout at 4.90 V) • I short circuit: 620 mA @ 120 Vac; 606 mA @ 230 Vac • Vac regulation dropout: 85 Vac with 500 mA load; Vout = 4.90 V • Output Ripple (500 mA load): 90 mV p/p • Standby Input Power: < 100 mW y 90 mW @ 230 Vac y 75 mW @ 120 Vac Efficiency - no auxiliary winding 80% 70% 60% 50% 40% 30% 20% 10% 0% Efficiency Efficiency Efficiency with auxiliary winding 120 Vac 230 Vac 0 100 200 300 400 80% 70% 60% 50% 40% 30% 20% 10% 0% 500 120 Vac 230 Vac 0 Load (mA) 100 200 300 400 500 Load (mA) CV - CC Profile 6 Vout (V) 5 4 3 Vout (V) 2 1 0 0 100 200 300 400 500 600 700 Load (m A) 1 © 2006 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] October 2006, Rev. 1 www.onsemi.com 4