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
Alternative Low Power Mode for Power Supplies
Computers continue to change and introduce 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 new power states have created requirements for power supplies. Below is a summary of these requirements as they are mentioned throughout the document.
- Section Section 4.2.4 – Other Lower Power System Requirements:
- Table 4-5 shows that ALPM requirements are at the 0.55 A and 1.5 A load levels.
- Section 4.3 - Timing, Housekeeping and Control:
- Table 4-9 has a column for require values of T1 and T3 to support ALPM.
- Section Section 4.2.2–Reliability – PS_ON# Toggle for S0ix Mode and 4.2.2Section 10.2:
- The number of times a PSU toggles on and off is expected to increase.
- PSU response quickly to toggling of PS_ON# signal.
Section Section 4.3.3: