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Intel ATX12V manual Introduction, Scope, Increased +12 VDC output capability, Minimum Efficiency

Models: ATX12V

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1. Introduction

ATX12V Power Supply Design Guide

Version 2.0

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 configuration, and pertinent electrical and signal timing specifications.

This document is provided as a convenience only and is not intended to replace the user’s independent design and validation activity. It should not be inferred that all ATX12V power supplies must conform exactly to the content of this document. The design specifics described herein are not intended to support all possible system configurations. System power supply needs vary widely depending on factors such as the application (that is, for desktop, workstation, or server), intended ambient environment (temperature, line voltage), or motherboard power requirements.

1.2.Key Changes for ATX12V Version 2.0 as Compared with ATX Power Supply

This section briefly summarizes the major changes made to this document that now defines ATX12V power supply. With the move to 12V voltage regulators for the processor, ATX guidelines for 5V as main power are no longer provided.

1.2.1. Increased +12 VDC output capability

System components that use 12V are continuing to increase in power. In cases where expected current requirements is greater than 18A a second 12 V rail should be made available. ATX12V power supplies should be designed to accommodate these increased +12 VDC currents.

1.2.2. Minimum Efficiency

Minimum measured efficiency is required to be 70% at full and typical (~50%) load and 60% at light (~20%) load. New recommended guidance has been added to provide direction for future requirements.

†2.03 is the current version of the ATX Specification as of this writing. Future references to the ATX Specification in this document imply version 2.03 or later, as applicable.

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Intel ATX12V manual Introduction, Scope, Increased +12 VDC output capability, Minimum Efficiency

Contents

ATX12V Power Supply Design Guide VersionIMPORTANT INFORMATION AND DISCLAIMERS Applicable Documents ContentsIntroduction Electrical5. Environmental Safety4. Mechanical 6. Electromagnetic CompatibilityATX12V Power Supply Design Guide Version FiguresTables 1.2.1. Increased +12 VDC output capability 1. Introduction1.1. Scope 1.2.2. Minimum Efficiency1.2.3. Main Power Connector 1.2.4. Separate current limit for 12V2 on the 2x2 connector1.3 Terminology 2. Applicable Documents Document TitleDescription 3.1.1. Input Over-current Protection 3. Electrical3.1. AC Input 3.1.2. Inrush Current LimitingPRODUCT SAFETY 3.1.3. Input Under-voltage3.1.4. Regulatory ELECTROMAGNETIC CAMPATIBILITY3.2. DC Output 3.1.5. Catastrophic Failure Protection3.2.1. DC Voltage Regulation 3.2.3. Typical Power Distribution 3.2.2. Remote Sensing3.2.3.1. ATX12V Configurations Table 3. Typical Power Distribution for a 250 W ATX12V ConfigurationFigure 1. Cross Loading Graph for 250W Configuration Table 4. Typical Power Distribution for a 300 W ATX12V Configuration Figure 2. Cross Loading Graph for 300W ConfigurationTable 5. Typical Power Distribution for a 350 W ATX12V Configuration Figure 3. Cross Loading Graph for 350W ConfigurationTable 6. Typical Power Distribution for a 400 W ATX12V Configuration Figure 4. Cross Loading Graph for 400W Configuration3.2.5.1. General 3.2.4. Power Limit / Hazardous Energy Levels3.2.5. Efficiency Table 7. Minimum Efficiency Vs LoadATX12V Power Supply Design Guide Table 8. Loading Table for Efficiency Measurements3.2.5.3. Other Low Power System Requirements 3.2.6. Output Ripple/NoiseTable 9. Energy Star Input Power Consumption 3.2.5.2. Energy StarTable 10. DC Output Noise/Ripple Figure 5. Differential Noise Test SetupPower Supply ScopeTable 11. DC Output Transient Step Sizes 3.2.7. Output Transient Response3.2.8. Capacitive Load Table 12. Output Capacitive Loads3.2.9. Closed-loop Stability 3.2.10. +5 VDC / +3.3 VDC Power Sequencing3.3. Timing / Housekeeping / Control 3.2.11. Voltage Hold-up Time3.3.1. PWROK 3.3.2. PSON#Table 13. PWROK Signal Characteristics 3.3.3. +5 VSB Table 14. PSON# Signal CharacteristicsFigure 7. PSON# Signal Characteristics 3.3.8. +5 VSB at AC Power-down 3.3.4. Power-on Time3.3.7. Reset after Shutdown 3.3.5. Risetime3.4.2. Short-circuit Protection 3.4. Output Protection3.4.1. Over-voltage Protection 3.4.3. No-load Operation3.4.5. Over-temperature Protection 3.4.6. Output Bypass4.2. Physical Dimensions 4. Mechanical4.1. Labeling / Marking Second optional fan may go in this location Air inlet grill, 55% open areain optional venting Second optionalfan may be located area or on topside4.3. Airflow / Fan 4.4. AC Connector 4.5. DC ConnectorsMain Power Connector PSON#4.5.1. ATX Main Power Connector 4.5.2. +12 V Power Connector 4.5.3. Peripheral ConnectorsATX12V Power Supply Design Guide Version This is a required connector for systems with Serial ATA devices 4.5.4. Serial ATA Power Connector4.5.5. Floppy Drive Connector Figure 11. Serial ATA ConnectorThermal Shock Shipping EnvironmentalTemperature Humidity5.7. Acoustics 5.5. Mechanical Shock5.6. Random Vibration ATX12V Power Supply Design Guide Version 2.0 Final Review Copy6. Electromagnetic Compatibility 6.1. Emissions6.2. Immunity 6.3. Input Line Current Harmonic Content and Line Flicker 6.4. Magnetic Leakage FieldsTable 16. Harmonic Limits, Class D Equipment 7. Reliability 7.1. Component De-rating8. Safety 8.1. North America8.2. International 8.3. Proscribed Materials