ATX Version 3.0 Multi Rail Desktop Platform Power Supply
Design Guide
ID
336521
Date
02/01/2023
Public
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Revision History
Introduction
Processor Configurations
PCI Express* Add-in Card Considerations
Electrical
Mechanical
Acoustics
Environmental
Electromagnetic Compatibility
Safety
Reliability
CFX12V Specific Guidelines 2.0
LFX12V Specific Guidelines 2.0
ATX12V Specific Guidelines 3.0
SFX12V Specific Guidelines 4.0
TFX12V Specific Guidelines 3.0
Flex ATX Specific Guidelines 2.0
DC Output – REQUIRED
DC Voltage Regulation – REQUIRED
DC Output Current – REQUIRED
Remote Sensing - RECOMMENDED
Other Low Power System Requirements
Output Ripple Noise - REQUIRED
Capacitive Load – RECOMMENDED
Closed Loop Stability - REQUIRED
+5V DC / +3.3V DC Power Sequencing - REQUIRED
Voltage Hold-Up Time - REQUIRED
12V2 DC Minimum Loading - REQUIRED
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 4.0
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
Fan Requirements - REQUIRED
Standard SFX Profile Package – Physical Dimensions - REQUIRED
Fan Requirements - REQUIRED
PS3 Form Factor-Physical Dimensions - REQUIRED
Fan Requirements - REQUIRED
PCI Express* Add-in Card Considerations
The PCI Express* (PCIe*) Card Electromechanical Specification (CEM Spec) provides thermal, power, mechanical, and signal integrity design guidance for the PCI Express* Add-in Card (AIC) form factor. This includes the card’s electrical and mechanical interface with a host system board, chassis, and power supply.
The 5.0 Revision of the PCIe* spec introduces four significant updates that directly affect this power supply specification:
- A Power Excursion allowance was introduced to support brief, high current demands on power, beyond the rated TDP.
- The maximum power consumption for a single Add-in Card was doubled to 600 W. This is the per-card limit from all sources combined.
- A new 48V (nominal) power rail was added.
- Two new Auxiliary Power Connectors were introduced to provide the full 600 W on a single cable connector. The new 12VHPWR connector supports 600W on the 12V rail while the 48VHPWR provides 600W on the 48V rail. Four new sideband signal conductors permit simple signaling between the Add-in Card and power supply.