Design Idea DI-21 ® TOPSwitch-GX 45 W, Universal ® Input, LCD Monitor External Adapter Application Device Power Output Input Voltage Output Voltage Topology LCD Monitor TOP247Y 45 W 90-265 VAC 12 V Flyback Design Highlights current limit is further reduced as a function of line voltage by R4-R6 to provide approximately constant overload power vs. line. The larger TOPSwitch-GX selection reduces conduction losses, raising efficiency (without circuit changes or increased overload power), and permits a high inductance design with a small EE30 core for higher efficiency. • High efficiency, >82% at 90 VAC • Low part count solution • Extremely low EMI – frequency jitter helps meet EN55022B and FCC B limits with output return grounded • Low zero load power consumption, <250 mW at 115 VAC • Line undervoltage detection (UV) and overvoltage (OV) power system surge protection • Differential and common mode surge immunity to 4 kV (EN61000-4-5) • 100 kHz ring wave immunity to 4 kV (IEEE C62.41) Key Design Points • Nominal UV and OV set points are calculated according to the equations: VUV = (50 µA x R1) + 2.5 V, VOV= (R1 x 225 µA) + 2.9 V • C2 provides high frequency bypass for high voltage DC bus, reducing high frequency EMI. • C3 reduces clamp Zener temperature and increases efficiency. R18 in series with C3 damps drain ringing. • Ferrite beads, instead of RC snubbers are used on output rectifier D7 to reduce zero load power consumption. • L5 and L6 reduce common mode conducted interference at high frequencies (>10 MHz). • T1 shield winding (pins 2-3) reduces EMI. R7 damps ringing caused by shield capacitive currents. Operation The design in Figure 1 utilizes the TOP247Y and takes advantage of many of the device’s features. Line UV and OV (100 V and 450 V, respectively) are implemented using a single 2 MΩ resistor (R1). Undervoltage eliminates power-up/down output glitches and overvoltage provides protection for both short duration transients and long duration power system surges, removing the need for an input MOV. Resistor R8 programs the internal current limit of the TOP247Y to 50% of nominal. The R4-R6 2.7 MΩ D1 D2 CY1 R7 2.2 nF 220 Ω Y1 R18 68 Ω 0.5 W VR1 P6KE 200 R4 D1-D4 RL205 2 A, 600 V F1 L 3.15 A 90-265 VAC N CX1 330 nF X2 t° C1 100 µF 400 V C2 20 nF 1 kV R5 2 3 C3 4.7 nF 1 kV D5 UF4005 R6 D3 1 R1 2 MΩ 0.5 W D 7, 9 D4 S R8 15 kΩ C7, C8 680 µF 35 V F C4 100 nF C10 100 nF C9 220 µF 35 V RTN 10,12 5 D6 1N4148 4 6 TOPSwitch-GX U1 CONTROL CONTROL C TOP247Y X L6 1T Through Ferrite Bead 12 V, 3.75 A L2 3.3 µH, 5 A C6 1 µF 50 V U2 LTV817A R11 1 kΩ L GND L5 3T Ground Wire Through Ferrite Bead L4 Bead T1 D7 MBR20100 L1 10 mH 1.4 A RT1 5 Ω, 2.8 A L3 Bead Note: Beads L3 and L4 are placed on D7 anode leads R10 470 Ω R9 6.8 Ω C5 47 µF 10 V C12 22 µF 25 V R13 38.3 kΩ 1% C11 47 nF R12 4.7 kΩ U3 TL431 R14 10 kΩ 1% PI-3003-051303 Figure 1. TOPSwitch-GX 45 W LCD Monitor Adapter. DI-21 www.powerint.com May 2003 DI-21 EE30 TDK PC40EE30-Z or equivalent, Gap for ALG of 1045 nH/T2 Bobbin E130 12 pin (Yih Hwa YW-016 or equivalent) Winding Details Shield: 10T, 2 x 28 AWG Primary: 22T, 25 AWG Bias: 3T, 4 x 28 AWG Secondary: 3T, 5 x 25 AWG T.I.W. (T.I.W. = Triple Insulated Wire) Winding Order (Pin Numbers) Tape, Shield (2-3), Tape, Primary (4-1), Tape, Bias (6-5), Tape, Secondary (7,8,9-10,11,12), Tape Inductance Primary: 490 µH ± 10%, Leakage: 6 µH (maximum) Primary Resonant Frequency 2 MHz (minimum) Table 1. Transformer Construction Information. PI-3004-073102 QP Limit Line 60 AV Limit Line 50 40 30 20 -10 0 Quasi-Peak Scan Average Scan -10 -20 0.15 1 EN_V_QP EN_V_AV 10 30 Frequency (MHz) Figure 2. 115 V Conducted EMI for LCD Monitor Supply. Meets FCC Part 15 Class B. 80 PI-3005-073102 Core Material 70 Amplitude (dBµV) TRANSFORMER PARAMETERS 80 70 QP Limit Line 60 Amplitude (dBµV) • Capacitor C12 is added to eliminate output start-up overshoot. • Feedback compensation is accomplished with C11 and R12 across TL431 reference amplifier U3 and correct choice of optocoupler series resistor R10. AV Limit Line 50 40 30 20 -10 0 Quasi-Peak Scan Average Scan -10 -20 0.15 1 EN_V_QP EN_V_AV 10 30 Frequency (MHz) Figure 3. 230 V Conducted EMI for LCD Monitor Supply. Meets EN55022 EMI spec. For the latest updates, visit our Web site: www.powerint.com Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power Integrations does not assume any liability arising from the use of any device or circuit described herein, nor does it convey any license under its patent rights or the rights of others. The products and applications illustrated herein may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com. The PI Logo, TOPSwitch, TinySwitch and EcoSmart are registered trademarks of Power Integrations, Inc. PI Expert is a trademark of Power Integrations, Inc. ©Copyright 2003, Power Integrations, Inc. WORLD HEADQUARTERS AMERICAS Power Integrations, Inc. San Jose, CA 95138 USA Customer Service: Phone: +1 408-414-9665 Fax: +1 408-414-9765 e-mail: [email protected] CHINA Power Integrations International Holdings, Inc. China Phone: +86-755-8367-5143 Fax: +86-755-8377-9610 e-mail: [email protected] B 5/03 EUROPE & AFRICA Power Integrations (Europe) Ltd. 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