ATX12V電源設計指南(pdf 43頁)(英文)

1. Introduction ....................................................................................................... 6
1.1. Scope ....................................................................................................................................6
1.2. Key Changes for ATX12V Version 2.0 as Compared with ATX Power Supply......................6
1.2.1. Increased +12 VDC output capability ........................................................................6
1.2.2. Minimum Efficiency....................................................................................................6
1.2.3. Main Power Connector: .............................................................................................7
1.2.4. Separate current limit for 12V2 on the 2x2 connector: ...............................................7
1.3 Terminology............................................................................................................................7
2. Applicable Documents ..................................................................................... 8
3. Electrical ............................................................................................................ 9
3.1. AC Input.................................................................................................................................9
3.1.1. Input Over-current Protection ....................................................................................9
3.1.2. Inrush Current Limiting ..............................................................................................9
3.1.3. Input Under-voltage ...................................................................................................10
3.1.4. Regulatory..................................................................................................................10
3.1.5. Catastrophic Failure Protection .................................................................................11
3.2. DC Output..............................................................................................................................11
3.2.1. DC Voltage Regulation ..............................................................................................11
3.2.2. Remote Sensing ........................................................................................................12
3.2.3. Typical Power Distribution .........................................................................................12
3.2.4. Power Limit / Hazardous Energy Levels ....................................................................17
3.2.5. Efficiency ...................................................................................................................17
3.2.6. Output Ripple/Noise...................................................................................................19
3.2.7. Output Transient Response.......................................................................................21
3.2.8. Capacitive Load .........................................................................................................21
3.2.9. Closed-loop Stability ..................................................................................................22
3.2.10. +5 VDC / +3.3 VDC Power Sequencing ..................................................................22
3.2.11. Voltage Hold-up Time..............................................................................................22
3.3. Timing / Housekeeping / Control ............................................................................................22
3.3.1. PWR_OK...................................................................................................................23
3.3.2. PS_ON#.....................................................................................................................23
3.3.3. +5 VSB.......................................................................................................................24
3.3.4. Power-on Time ..........................................................................................................25
3.3.5. Risetime.....................................................................................................................25
3.3.6. Overshoot at Turn-on / Turn-off.................................................................................25
3.3.7. Reset after Shutdown ................................................................................................25
3.3.8. +5 VSB at AC Power-down........................................................................................25
3.4. Output Protection....................................................................................................................26
3.4.1. Over-voltage Protection .............................................................................................26
3.4.2. Short-circuit Protection ..............................................................................................26
3.4.3. No-load Operation .....................................................................................................26
3.4.4. Over-current Protection .............................................................................................26
3.4.5. Over-temperature Protection .....................................................................................27
3.4.6. Output Bypass ...........................................................................................................27
4. Mechanical......................................................................................................... 28
4.1. Labeling / Marking ..................................................................................................................28
4.2. Physical Dimensions ..............................................................................................................28
4.3. Airflow / Fan............................................................................................................................31
4.4. AC Connector .........................................................................................................................32
4.5. DC Connectors......................................................................................................................32
4.5.1. ATX Main Power Connector ......................................................................................34
4.5.2. +12 V Power Connector.............................................................................................35
4.5.3. Peripheral Connector(s).............................................................................................35
4.5.4. Serial ATA Power Connector.....................................................................................36
4.5.5. Floppy Drive Connector .............................................................................................36
5. Environmental ................................................................................................... 37
5.1. Temperature..........................................................................................................................37
5.2. Thermal Shock (Shipping)......................................................................................................37
5.3. Humidity.................................................................................................................................37
5.4. Altitude...................................................................................................................................37
5.5. Mechanical Shock ..................................................................................................................38
5.6. Random Vibration...................................................................................................................38
5.7. Acoustics ...............................................................................................................................38
6. Electromagnetic Compatibility......................................................................... 39
6.1. Emissions ...............................................................................................................................39
6.2. Immunity..................................................................................................................................39
6.3. Input Line Current Harmonic Content and Line Flicker ..........................................................40
6.4. Magnetic Leakage Fields........................................................................................................40
7. Reliability ........................................................................................................... 41
7.1. Component De-rating .............................................................................................................41
8. Safety ................................................................................................................. 42
8.1. North America ........................................................................................................................42
8.2. International...........................................................................................................................43
8.3. Proscribed Materials...............................................................................................................43
ATX12V Power Supply Design Guide
Version 2.0
5
Figures
Figure 1. Cross Loading Graph for 250W Configuration .......................................................................13
Figure 2. Cross Loading Graph for 300W Configuration .......................................................................14
Figure 3. Cross Loading Graph for 350W Configuration .......................................................................15
Figure 4. Cross Loading Graph for 400W Configuration .......................................................................16
Figure 5. Differential Noise Test Setup.................................................................................................20
Figure 6. Power Supply Timing.............................................................................................................22
Figure 7. PS_ON# Signal Characteristics.............................................................................................24
Figure 8. Power Supply Dimensions for Chassis That Does Not Require Top Venting .......................29
Figure 9. Power Supply Dimensions for Chassis That Require Top Venting........................................30
Figure 10. ATX12V Power Supply Connectors.....................................................................................33
Figure 11. Serial ATA Connector ...........................................................................................................36
Tables
Table 1. AC Input Line Requirements...................................................................................................9
Table 2. DC Output Voltage Regulation................................................................................................11
Table 3. Typical Power Distribution for a 250 W ATX12V Configuration..............................................13
Table 4. Typical Power Distribution for a 300 W ATX12V Configuration..............................................14
Table 5. Typical Power Distribution for a 350 W ATX12V Configuration..............................................15
Table 6. Typical Power Distribution for a 400 W ATX12V Configuration..............................................16
Table 7. Minimum Efficiency Vs Load...................................................................................................17
Table 8. Loading Table for Efficiency Measurements...........................................................................18
Table 9. Energy Star Input Power Consumption...................................................................................19
Table 10. DC Output Noise/Ripple........................................................................................................20
Table 11. DC Output Transient Step Sizes...........................................................................................21
Table 12. Output Capacitive Loads.......................................................................................................21
Table 13. PWR_OK Signal Characteristics ..........................................................................................23
Table 14. PS_ON# Signal Characteristics ............................................................................................24
Table 15. Overvoltage Protection .........................................................................................................26
Table 16. Harmonic Limits, Class D Equipment ...................................................................................40

1. Introduction
1.1. Scope
This document provides design suggestions and reference specifications for a family of
power supplies that comply with the ATX Specification, Version 2.03? for motherboards
and chassis. It includes supplementary information not expressly detailed in the ATX
Specification, such as information about the physical form factor of the power supply,
cooling requirements, connector

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