TopSwitchGX 180W
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www.powerint.com Design Idea DI-30 TOPSwitch-GX 180 W PC Main SFX Supply December 2002 DI-30 ® Application PC Main TOP249Y 3.3 V / 5 V / 12 V / -12 V Power Output 180 W Input Voltage Output Voltage Topology Device 90-130 VAC / 180-265 VAC Forward Design Highlights • 180 W cont. (200 W peak) in PC SFX form factor • Includes passive power factor correction (PFC) • TOPSwitch-GX integrated features enable extremely low component count • Meets 1 W standby spec (0.91 W input, 0.5 W output) • High efficiency (71% minimum) • Integrated line undervoltage and overvoltage detection • Low EMI due to frequency jitter • SOURCE referenced TO-220 tab lowers conducted EMI • Maximum duty cycle reduction (DC MAX ) prevents transformer saturation for fault and transient loads • Uses conventional magamp for 3.3 V output • Meets CISPR22B/EN55022B conducted EMI Operation TOPSwitch-GX integrates many features designed for use with forward converters. Passive power factor correction (PFC) is implemented using inductors LPFC1 and LPFC2. Transistors Q4, Q6, R1, R2, R3, R5, and R6 form an active capacitor (C2, Figure 1. 180 W (200 W pk.) PC Main Power Supply Schematic (Note: Schematic does not include transformer Y-capacitor). C3) balancing circuit, operating only as needed to minimize zero-load power consumption. Resistors R3, R5 and R6 implement start-up undervoltage lockout, which prevents the supply from starting below 180 VDC. Components R4, R14, Q1 and R30 implement an independent undervoltage using the X pin, which allows the supply to continue delivering power all the way down to 140 VDC (increasing holdup time). Resistor R7 provides additional hysteresis. The primary side components D1, VR3-5 and C4, along with secondary side C9 and R30, implement the Zener/capacitor reset/clamp circuit. This circuit provides reset voltage for the transformer and clamps the DRAIN pin voltage to a safe level (<~600 V) under all conditions. The reset circuit works in conjunction with the DC MAX reduction circuit (R8, R36, C22, VR19 and D18) to limit the maximum duty cycle and prevent transformer saturation under fault and transient conditions. ® C13 220 μF 63 V C3 470 μF 200 V C2 470 μF 200 V L G N RTN +5 V +12 V R20 270 kΩ R16 1 kΩ U5 TL431 D S C L F X CONTROL R19 4.12 kΩ 1% F1 4 A RV1 275 V, 14 mm R10 560 K 1/2 W CX2 0.33 μF 250V CY4 2.2 nF (Safety) RT1 10 Ω CY3 2.2 nF (Safety) JP9 CX1 0.047 μF 250 VAC L7 8.2 mH BR1 KBL06 To AC Selector Switch R1 330 kΩ R2 330 kΩ D1 1N5407 R3 2.2 MΩ R5 180 kΩ R6 2.2 MΩ R8 130 kΩ 1% R14 75 kΩ R12 12 kΩ R30 3.3 kΩ Q1 2N3908 C22 100 pF 50 V C10 1 nF 50 V C20 330 pF 50 V D7 MBR3045 R36 43.2 kΩ 1% R13 10 Ω D18 BAV20 VR19 1N5229 R4 2.2 MΩ R7 560 kΩ R11 300 Ω Coupled choke L1 13 μH R30 1 Ω 1 W D8 MBR6045 C9 47 nF 50 V C12 2200 μF 6.3 V C11 1000 μF 16 V L2 0.5 μH U2 SFH615A-2 R17 15 kΩ C16 100 nF 50 V D6 BAV20 C8 0.033 μF 50 V R9 47 Ω C6 47 μF 16 V C7 100 nF 50 V D105 1N4148 Remote ON/OFF R38 5.1 kΩ U3 LTV817 R37 10 kΩ R106 27 kΩ +12 V STBY C23 33 nF 50 V VR3 BZY97C- 200 C4 2.2 nF 1 kV VR4 BZY97C- 180 VR5 BZY97C- 180 D20 UF4002 C5 1 μF 100 V C27 330 pF 50 V R11 330 Ω LM 320 C25 1 μF 50 V TO MAGAMP OUT (3.3 V) - 12 V R18 4.74 kΩ 1% R15 1.8 kΩ C17 100 nF 50 V C24 330 μF 25 V Q7 2N3904 PI-3384-120902 TOPSwitch-GX U1 TOP249 2 1 13 14 11,12 8, 9, 10 4 3 4 5 1, 2 7, 8 3 6 Q6 MPSA92 Q4 MPSA42 R21 270 Ω LPFC1 LPFC2
description
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Transcript of TopSwitchGX 180W
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www.powerint.com
Design Idea DI-30TOPSwitch-GX180 W PC Main SFX Supply
December 2002DI-30
ApplicationPC Main TOP249Y 3.3 V / 5 V / 12 V / -12 V
Power Output180 W
Input Voltage Output Voltage TopologyDevice90-130 VAC / 180-265 VAC Forward
Design Highlights 180 W cont. (200 W peak) in PC SFX form factor Includes passive power factor correction (PFC) TOPSwitch-GX integrated features enable extremely low
component count Meets 1 W standby spec (0.91 W input, 0.5 W output) High efficiency (71% minimum) Integrated line undervoltage and overvoltage detection Low EMI due to frequency jitter SOURCE referenced TO-220 tab lowers conducted EMI Maximum duty cycle reduction (DCMAX) prevents transformer
saturation for fault and transient loads Uses conventional magamp for 3.3 V output Meets CISPR22B/EN55022B conducted EMI
OperationTOPSwitch-GX integrates many features designed for use withforward converters. Passive power factor correction (PFC) isimplemented using inductors LPFC1 and LPFC2. TransistorsQ4, Q6, R1, R2, R3, R5, and R6 form an active capacitor (C2,
Figure 1. 180 W (200 W pk.) PC Main Power Supply Schematic (Note: Schematic does not include transformer Y-capacitor).
C3) balancing circuit, operating only as needed to minimizezero-load power consumption.
Resistors R3, R5 and R6 implement start-up undervoltagelockout, which prevents the supply from starting below180 VDC. Components R4, R14, Q1 and R30 implement anindependent undervoltage using the X pin, which allows thesupply to continue delivering power all the way down to140 VDC (increasing holdup time). Resistor R7 providesadditional hysteresis.
The primary side components D1, VR3-5 and C4, along withsecondary side C9 and R30, implement the Zener/capacitorreset/clamp circuit. This circuit provides reset voltage for thetransformer and clamps the DRAIN pin voltage to a safe level(
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www.powerint.comB12/02
DI-30
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Figure 2. Magamp for Independent 3.3 V Secondary Regulation.
The components R12, C7, R38, Q7, C23, R37, U3, R106 andD105 implement the remote ON/OFF drive circuit. Duringthe ON state, U3 and hence Q7 conduct, pulling the X pin toSOURCE via resistor R12 (which sets the current limit).
During the OFF state, U3 and Q7 are off, allowing the X pinto be pulled high by the +15 V standby supply via R38 and R12and putting the TOPSwitch-GX into the OFF state. ComponentsR38 and D105 reduce device consumption to around 2mW bysupplying external current to the CONTROL pin from the+15 V standby supply. Resistor R11 is required to allowexternal bias feed.
Key Design Points The passive PFC inductors (LPFC1 and LPFC2) are
constrained by both thermal and efficiency requirements.Design of these inductors is not covered in this Design Idea.
Transformer reset: Use recommended Zener/capacitor
clamp/reset circuit to maintain drain voltage < 600 V andDCMAX reduction to prevent transformer saturation.
Maintain maximum flux density on transformer (T1)< 2500 gauss.
Check for balanced currents on coupled inductor (L1) forall load combinations.
Use PI Expert (PIXls) Design Spreadsheet and refer toApplication Note AN-30 for details on designing forwardconverters with TOPSwitch-GX.
This particular PC SFX 12 specification delivers a largerproportion of power on the 12 V winding; efficiency would belower if that power were drawn from the 3.3 V output.
Due to the complexity of this design it is not possible to includeall details in this Design Idea. An Engineering Prototype Report(EPR) will be available for this design Dec. 2000. For updatesand all other information please refer to Power Integrations'Web site.
For the latest updates, visit our Web site: www.powerint.comPower 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 anylicense under its patent rights or the rights of others. The products and applications illustrated herein (including circuits external to theproducts and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreignpatent applications assigned to Power Integrations. A complete list of Power Integrations patents may be found at www.powerint.com.The PI Logo, TOPSwitch, TinySwitch, LinkSwitch and EcoSmart are registered trademarks of Power Integrations, Inc.PI Expert is a trademark of Power Integrations, Inc. Copyright 2002, Power Integrations, Inc.
3.3 V
RTNRTN
PI-3385-093002
D11UF4002 D10
UF4002
R223
Q2TIP32
D9MBR2045 L420 H
L50.5 H
R3433
R27390
R231 k
R252.7 k
C180.1 F50 V
R243.84 k
1%
R2610 k
1%U8
TL431
C211 F50 V
L3Mag Amp6 Turns
C141200 F
10 V
C151200 F
10 V
FROM MAINCONVERTER5 V WINDING
