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)
Timing, Housekeeping, and Control – REQUIRED
Figure 4-2: Power on Timing
Table 4-9: Power Supply Timing
Parameter | Description | Value | |
Required | Recommended | ||
T0 | AC power on time7 | <2s | |
T1 | Power-on time6 | <150ms1 | <100 ms |
T2 | Rise time | 0.2–20 ms | |
T3 | PWR_OK delay6 | 1ms – 150ms1 | 1–100 ms |
T4 | PWR_OK rise time | < 10 ms | |
T5 | AC loss to PWR_OK hold-up time | > 11 ms2 | > 16 ms3 |
T6 | PWR_OK inactive to DC loss delay | > 1 ms4 | > 1 ms5 |
- T1 and T3 required values are set to meet timing requirement for computers that use ALPM.
- T5 Required value to be defined for both Full/Light load condition.
- T5 Recommended value is defined for 80% of full load condition.
- T6 Required value to be defined for coming from both Full/Light load conditions.
- T6 Recommended value is defined for coming from 80% of full load condition.
- PSUs are recommended to label or indicate the timing value for system designer and integrator reference for T1 and T3. This allows system designers to optimize “turn on” time within the system.
- T0 is shown in Section 4.3.3, Figure 4-4.