ATX12VO (12V Only) Desktop Power Supply
Design Guide
ID
613768
Date
05/01/2024
Public
Legal
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)
System Power Telemetry Feature
When ATX12VO was designed one pin was reserved in the main 10 pin connector for a Telemetry feature. This Telemetry feature is the ability of the power supply to report the percentage of rated power being used by the system. The system components can then react when the power supply rated power limit is reached or exceeded. This is reported as a percentage because power supplies come in many different power ratings and there is no way for the power supply to tell the system its rated power limit. The percentage method allows for a consistent method of telemetry between all ATX12VO power supplies and the system.
The electrical details are explained further in Section 4.3.7.