ATX12VO (12V Only) Desktop Power Supply
Design Guide
ID
613768
Date
11/01/2023
Public
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Introduction
Processor Configurations
PCI Express* Add-in Card Considerations
Electrical
Mechanical
Acoustics
Environmental
Electromagnetic Compatibility
Safety
Reliability
CFX12V Specific Guidelines 2.1
LFX12V Specific Guidelines 2.1
ATX12V Specific Guidelines 3.1
SFX12V Specific Guidelines 4.1
TFX12V Specific Guidelines 3.1
Flex ATX Specific Guidelines 2.1
DC Output – REQUIRED
DC Voltage Regulation – REQUIRED
DC Output Current – REQUIRED
Remote Sensing – RECOMMENDED
Other Low Power System Requirements – REQUIRED
Output Ripple Noise – REQUIRED
Capacitive Load – RECOMMENDED
Closed Loop Stability – REQUIRED
Multiple 12V Rail Power Sequencing – REQUIRED
Voltage Hold-Up Time – REQUIRED/RECOMMENDED
Over Voltage Protection (OVP) - REQUIRED
Short Circuit Protection (SCP) - REQUIRED
No-Load Situation - REQUIRED
Over Current Protection (OCP) - REQUIRED
Over Temperature Protection (OTP) - REQUIRED
Output Bypass - REQUIRED
Separate Current Limit for 12V2 - OPTIONAL
Overall Power Supply Efficiency Levels
Power Supply Efficiency for Energy Regulations – ENERGY STAR* and CEC (California Energy Commission) PC Computers with High Expandability Score – RECOMMENDED
SFX12V Specific Guidelines 4.1
Lower Profile Package – Physical Dimensions (Required)
Fan Requirements (Required)
Top Fan Mount Package – Physical Dimensions (Required)
Fan Requirements (Required)
Reduced Depth Top Mount Fan – Physical Dimensions (Required)
Fan Requirements (Required)
Standard SFX Profile Package – Physical Dimensions (Required)
Fan Requirements (Required)
PS3 Form Factor – Physical Dimensions (Required)
Fan Requirements (Required)
Power Supplies and Alternative Low Power Mode
Computers are continuing to change and introducing new power states. One of these new power states is generically called an Alternative Low Power Mode (ALPM). Some examples of Alternative Low Power Modes are Microsoft* Windows 10 Modern Standby or Google* Chrome Lucid Sleep. These low power states have created requirements for power supplies. Below is a summary of these requirements as they are mentioned throughout the document. All ALPM features are required in this Single Rail Desktop Power Supply Design Guide.
- Section 4.2.4: Other Lower Power System Requirements
- Table 4-5 shows that ALPM requirements are at the 230 mA and 625 mA load levels.
- Section 4.3:
- Table 4-10 “Required” timing values of T1 and T3 support ALPM. Multi rail power supply design guide has the Required T1 and T3 timing values as recommended for ALPM.
- Section 4.2.2– PS_ON#
- Section 10.2:
- The number of times a PSU toggles on and off is expected to increase.
- Section 4.3.2:
- PSU response quickly to toggling of PS_ON# signal.