Intel ATX Guide

Document Number: 336521 - 003
ATX Multi Rail Desktop Power
Supply
Design Guide
June 2020
Revision 003

2 Design Guide
You may not use or facilitate the use of this document in connection with any infringement or other legal analysis concerning Intel
products described herein. You agree to grant Intel a non-exclusive, royalty-free license to any patent claim thereafter drafted
which includes subject matter disclosed herein.
No license (express or implied, by estoppel or otherwise) to any intellectual property rights is granted by this document.
Intel technologies’ features and benefits depend on system configuration and may require enabled hardware, software or service
activation. Learn more at Intel.com, or from the OEM or retailer.
No computer system can be absolutely secure. Intel does not assume any liability for lost or stolen data or systems or any
damages resulting from such losses.
The products described may contain design defects or errors known as errata which may cause the product to deviate from
published specifications. Current characterized errata are available on request.
Intel disclaims all express and implied warranties, including without limitation, the implied warranties of merchantability, fitness
for a particular purpose, and non-infringement, as well as any warranty arising from course of performance, course of dealing, or
usage in trade.
ENERGY STAR is a system-level energy specification, defined by the US Environmental Protection Agency, which relies on all
system components, such as processor, chipset, power supply, etc. For more information, visit http://www.energystar.gov/.
All information provided here is subject to change without notice. Contact your Intel representative to obtain the latest Intel
product specifications and roadmaps.
Copies of documents which have an order number and are referenced in this document may be obtained by calling 1-800-548-
4725 or visit www.intel.com/design/literature.htm.
By using this document, in addition to any agreements you have with Intel, you accept the terms set forth below.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
Intel, Core, and the Intel logo are trademarks of Intel Corporation in the U.S. and/or other countries.
*Other names and brands may be claimed as the property of others.
Copyright © 2017-2020, Intel Corporation. All rights reserved.

Design Guide 3
Contents
1Introduction .....................................................................................................8
1.1 Alternative Low Power Mode for Power Supplies..........................................8
1.2 References ............................................................................................8
1.3 Terminology ..........................................................................................9
2Processor Configurations..................................................................................11
2.1 Processor Configurations – Recommended ...............................................11
2.2 High End Desktop Market Processor Considerations ...................................12
2.2.1 Modular Power Supply Connectors .............................................12
2.2.2 Overclocking Recommendations ................................................13
3Electrical .......................................................................................................14
3.1 AC Input - Required..............................................................................14
3.1.1 Input Over Current Protection – Required ...................................14
3.1.2 Inrush Current – Required ........................................................14
3.1.3 Input Under Voltage – Required ................................................14
3.2 DC Output - Required ...........................................................................15
3.2.1 DC Voltage Regulation – Required..............................................15
3.2.2 DC Output Current – Required...................................................15
3.2.3 Remote Sensing - Recommended ..............................................16
3.2.4 Other Low Power System Requirements - Recommended ..............16
3.2.5 Output Ripple Noise - Required .................................................17
3.2.6 Capacitive Load – Recommended...............................................18
3.2.7 Closed Loop Stability - Required ................................................18
3.2.8 +5V DC / +3.3V DC Power Sequencing - Required ....................... 18
3.2.9 Voltage Hold-Up Time - Required...............................................19
3.2.10 12V2 DC Minimum Loading - Required........................................19
3.3 Timing, Housekeeping, and Control – Required .........................................20
3.3.1 PWR_OK – Required ................................................................21
3.3.2 Power-Up Cross Loading Condition – Required .............................21
3.3.3 PS_ON# – Required.................................................................22
3.3.4 +5VSB – Required...................................................................23
3.3.5 Power-On Time – Required .......................................................24
3.3.6 Rise Time – Required ...............................................................24
3.3.7 Overshoot at Turn-On/Turn-Off – Required .................................25
3.4 Reset After Shutdown ...........................................................................25
3.4.1 +5VSB at Power-Down – Required.............................................25
3.4.2 +5VSB Fall Time - Recommendation ..........................................26
3.5 Output Protection .................................................................................26
3.5.1 Over Voltage Protection (OVP) – Required...................................26
3.5.2 Short Circuit Protection (SCP) – Required ...................................27
3.5.3 No-Load Situation – Required....................................................27
3.5.4 Over Current Protection (OCP) – Required...................................27
3.5.5 Over Temperature Protection (OTP) – Required ...........................27
3.5.6 Output Bypass – Required ........................................................27
3.5.7 Separate Current Limit for 12V2 - Recommended.........................27
3.5.8 Overall Power Supply Efficiency Levels .......................................28
3.5.9 Power Supply Efficiency for Energy Regulations - Energy Star* and
CEC PC Computers with High Expandability Score - Recommended.28

4 Design Guide
4Mechanical.....................................................................................................30
4.1 Labeling and Marking - Recommended ....................................................30
4.2 Connectors - Required ..........................................................................30
4.2.1 AC Connector .........................................................................30
4.2.2 DC Connectors........................................................................30
4.3 Airflow and Fans - Recommended ...........................................................35
4.3.1 Fan Location and Direction........................................................35
4.3.2 Fan Size and Speed .................................................................36
4.3.3 Venting..................................................................................36
5Acoustics .......................................................................................................37
5.1 Acoustics – Recommended ....................................................................37
6Environmental ................................................................................................38
6.1 Temperature – Recommended................................................................38
6.2 Thermal Shock (Shipping) – Recommended .............................................38
6.3 Humidity – Recommended .....................................................................38
6.4 Altitude – Recommended.......................................................................38
6.5 Mechanical Shock – Recommended .........................................................39
6.6 Random Vibration – Recommended.........................................................39
7Electromagnetic Compatibility ...........................................................................40
7.1 Emissions – Required ............................................................................40
7.2 Immunity - Required ............................................................................40
7.3 Input Line Current Harmonic Content - Optional ....................................... 40
7.4 Magnetic Leakage Field - Required ..........................................................41
7.5 Voltage Fluctuations and Flicker – Required..............................................41
8Safety ...........................................................................................................42
8.1 North America – Required......................................................................42
8.2 International – Required........................................................................43
8.3 Proscribed Materials - Required ..............................................................43
8.4 Catastrophic Failure Protection - Recommended........................................43
9Reliability ......................................................................................................44
9.1 Reliability - Recommended ....................................................................44
9.2 Reliability – PS_ON# Toggle for S0ix Mode - Required ...............................44
10 CFX12V Specific Guidelines 1.63 .......................................................................45
10.1 Physical Dimensions – Required..............................................................45
11 LFX12V Specific Guidelines 1.43........................................................................46
11.1 Physical Dimensions - Required ..............................................................46
12 ATX12V Specific Guidelines 2.53 .......................................................................49
13 SFX12V Specific Guidelines 3.43 .......................................................................51
13.1 Lower Profile Package - Physical Dimensions - Required .............................51
13.2 Fan Requirements - Required .................................................................51
13.3 Top Fan Mount Package - Physical Dimensions -Required ...........................53
13.4 Fan Requirements - Required .................................................................53
13.5 Reduced Depth Top Mount Fan - Physical .................................................54
13.6 Fan Requirements - Required .................................................................54

Design Guide 5
13.7 Standard SFX Profile Package – Physical Dimensions - Required .................. 55
13.8 Fan Requirements - Required .................................................................56
13.9 PS3 Form Factor- Physical Dimensions - Required .....................................57
13.10 Fan Requirements - Required .................................................................57
14 TFX12V Specific Guidelines 2.53........................................................................59
14.1 Physical Dimensions - Required ..............................................................59
14.2 Mounting Options - Recommended..........................................................61
14.3 Chassis Requirements - Recommended ...................................................62
15 Flex ATX Specific Guidelines 1.23 ......................................................................64
15.1 Physical Dimensions – Required..............................................................64
Figures
Figure 3-1: Differential Noise Test Setup ............................................................17
Figure 3-2: Power Supply Timing.......................................................................19
Figure 3-3: Power on Timing ............................................................................20
Figure 3-4: PS_ON# Signal Characteristics .........................................................23
Figure 3-5: +5VSB Power on Timing Versus VAC .................................................24
Figure 3-6: Rise Time Characteristics .................................................................25
Figure 3-7: 5VSB Fall Time...............................................................................26
Figure 4-1: Connectors (Pin-side View, Not to Scale)............................................31
Figure 4-2: Serial ATA* Power Connector ...........................................................35
Figure 10-1: CFX12V Mechanical Outline ............................................................45
Figure 11-1: LFX 12V Mechanical Outline............................................................46
Figure 11-2: Mechanical Details ........................................................................47
Figure 11-3: PSU Slot Feature Detail..................................................................47
Figure 11-4: Recommended Chassis Tab Feature.................................................48
Figure 12-1: Power Supply Dimensions for Chassis Not Requiring Top Venting .........49
Figure 12-2: Power Supply Dimensions for Chassis Requiring Top Venting ............... 50
Figure 13-1: 40 mm Profile Mechanical Outline....................................................52
Figure 13-2: Chassis Cutout .............................................................................52
Figure 13-3: Top Mount Fan Profile Mechanical Outline .........................................53
Figure 13-4: Chassis Cutout .............................................................................54
Figure 13-5: Recessed Fan Mounting .................................................................54
Figure 13-6: Reduced Depth Top Mount Fan Profile Mechanical Outline ...................55
Figure 13-7: Chassis Cutout .............................................................................55
Figure 13-8: 60 mm Mechanical Outline .............................................................56
Figure 13-9: Chassis Cutout .............................................................................57
Figure 13-10: PS3 Mechanical Outline ................................................................58
Figure 14-1: Mechanical Outline ........................................................................59
Figure 14-2: Dimensions and Recommended Feature Placements (Not to Scale) ...... 60
Figure 14-3: Power Supply Mounting Slot Detail ..................................................61
Figure 14-4: Fan Right and Fan Left Orientations of Power Supply in a Chassis ........62
Figure 14-5: Suggested TFX12V Chassis Cutout ..................................................62
Figure 14-6: Suggested Mounting Tab (Chassis Feature).......................................63
Figure 15-1: Mechanical Outline ........................................................................64
Figure 15-2: Dimensions and Recommended Feature Placements (Not to Scale) ...... 65

6 Design Guide
Tables
Table 1-1: Conventions and Terminology..............................................................9
Table 1-2: Support Terminology........................................................................10
Table 2-1: 12V2 Current for Processor Configurations ..........................................11
Table 3-1: AC Input Line Requirements ..............................................................14
Table 3-2: DC Output Voltage Regulation ...........................................................15
Table 3-3: DC Output Transient Step Sizes .........................................................15
Table 3-4: Recommended System DC and AC Power Consumption .........................16
Table 3-5: DC Output Noise/Ripple ....................................................................17
Table 3-6: Output Capacitive Loads ...................................................................18
Table 3-7: 12V2 DC Minimum Current................................................................19
Table 3-8: Power Supply Timing........................................................................20
Table 3-9: PWR_OK Signal Characteristics ..........................................................21
Table 3-10: PS_ON# Signal Characteristics.........................................................22
Table 3-11: Over Voltage Protection ..................................................................26
Table 3-12: Efficiency Versus Load Minimum Requirements...................................28
Table 3-13: Low Load Efficiency Requirements Increase Over Time ........................28
Table 3-14: Efficiency versus Load for Energy Star*.............................................29
Table 3-15: Efficiency Versus Load for CEC PC Computers with High Expandability
Computers* .............................................................................................29
Table 4-1: Main Power Connector Pin-Out...........................................................32
Table 4-2: Peripheral Connector Pin-Out.............................................................32
Table 4-3: Floppy Connector Pin-Out .................................................................33
Table 4-4: PCIe* Graphics Card 6 Pin Connector Pin-Out ......................................33
Table 4-5: PCI-E Graphics Card 8 Pin (6+2) Connector Pin-Out..............................33
Table 4-6: +12 V Power 4 Pin Connector Pin-Out.................................................34
Table 4-7: +12 V Power 8 Pin Connector Pin-Out.................................................34
Table 4-8: Serial ATA* Power Connector Pin-Out .................................................35
Table 5-1: Recommended Power Supply Acoustic Targets .....................................37
Table 7-1: EMC Requirement by Country ............................................................40

Design Guide 7
Revision History
Document
Number
Revision
Number
Description Revision Date
336521
001 •Initial Release September, 2017
002
•Updated Table 2-1: 12V2 Current for Processor
Configurations.
•Updated Figure 3: Power Supply Timing.
•Added Figure 5: +5VSB Power on timing versus VAC.
•Added note Table 4-8: +3.3V is removed from SATA
V3.2 spec.
•Updated Chapter 10:
−CFX12V Specific Guidelines to version 1.62
−LFX12V Specific Guidelines to version 1.42
−ATX12V Specific Guidelines to version 2.52
−SFX12V Specific Guidelines to version 3.42
−TFX12V Specific Guidelines to version 2.52
−Flex ATX Specific Guidelines to version 1.22
•Removed Chapter 16 test plan. Refer to Document
#595284 for test plan.
•Added Section 9.2. Reliability – PS_ON# toggle for S0ix
mode.
June, 2018
003
•Added Section 1.1 Alternative Low Power Mode for
Power Supplies.
•Updated Table 2-1: 12V2 Current for 10th Gen Intel®
CoreTM Processor Configurations.
•Added PSU Addendum for all future processor support
in Section 2.1.
•Update Table 3-4: 5VSB efficiency
•Updated Table 3-6: -12VDC capacitive load from
3300uF to 330uF.
•Updated Section 3.5.8 and added Table 3-13.
•Updated Section 3.5.9 to support Energy Star v8.
•Updated Section 4.3.2 for PS_ON# is asserted.
•Updated Section 9.2 Reliability – PS_ON# toggle for
S0ix mode.
•Updated Chapter 10-15:
−CFX12V Specific Guidelines to version 1.63
−LFX12V Specific Guidelines to version 1.43
−ATX12V Specific Guidelines to version 2.53
−SFX12V Specific Guidelines to version 3.43
−TFX12V Specific Guidelines to version 2.53
−Flex ATX Specific Guidelines to version 1.23
June, 2020
§ §

Introduction
8 Design Guide
1Introduction
This document provides design suggestions for various power supply form factors. The
power supplies are primarily intended for use with desktop system designs. It should
not be inferred that all power supplies must conform exactly to the content of this
document, though there are key parameters that define mechanical fit across a
common set of platforms. Since power supply needs vary depending on system
configuration, the design specifics described are not intended to support all possible
systems. The required sections are intended to be followed for all systems where the
recommended sections could be modified based on system design.
1.1 Alternative Low Power Mode for Power Supplies
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* Modern Standby or Google*
Chrome* Lucid Sleep. These new power states have created new requirements for
power supplies. Below is a summary of these requirements as they are mentioned
throughout the document.
•Section 3.2.4 – Other Lower Power System Requirements
Table 3-4 shows that ALPM requirements are at the 0.55A and 1.5A load levels.
•Section 3.3 – Timing, housekeeping and Control
Table 3-8 has a column for require values of T1 and T3 to support ALPM.
•Section 9.2 – Reliability – PS_ON# Toggle for S0ix Mode
The number of times a PSU toggles on and off is expected to increase.
1.2 References
The following documents are referenced in various sections of this design guide. The
document may not up-to-date; refer to the latest version. For guidelines not
specifically mentioned here, refer to the appropriate document.
Document Title Document
Number /Source
European Association of Consumer Electronics Manufacturers (EACEM*)
Hazardous Substance List / Certification AB13-94-146
IEEE* Recommended Practice on Surge Voltages in Low-Voltage AC Circuits ANSI* C62.41-1991
IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC
Power Circuits ANSI C62.45-1992
Nordic national requirement in addition to EN 60950 EMKO-TSE (74-
SEC) 207/94

Introduction
Design Guide 9
Document Title Document
Number /Source
American National Standard for Methods of Measurement of Radio-Noise
Emissions from Low-Voltage Electrical and Electronic Equipment in the Range
of 9 kHz to 40 GHz for EMI testing
ANSI C63.4
UL 60950-1 First Edition –CAN/CSA-C22.2 No. 60950-1-03
First Edition,
IEC 60950-1: 2001 + Amendments and National Deviations,
EN 60950-1: 2001 + Amendment A11:
EU Low Voltage Directive (73/23/EEC) (CE Compliance)
GB-4943 (China)
CNS 14336: (Taiwan BSMI)
FCC*, Class B, Part 15 (Radiated and Conducted Emissions)
CISPR* 22 / EN55022, 5th Edition (Radiated and Conducted Emissions)
EN55024 (ITE Specific Immunity)
EN 61000-4-2 – Electrostatic Discharge
EN 61000-4-3– Radiated RFI Immunity
EN 61000-4-4– Electrical Fast Transients
EN 61000-4-5 – Electrical Surge
EN 61000-4-6 – RF Conducted
EN 61000-4-8 – Power Frequency Magnetic Fields
EN 61000-4-11 – Voltage Dips, Short Interrupts and Fluctuations
EN61000-3-2 (Harmonics)
EN61000-3-3 (Voltage Flicker)
EU EMC Directive ((8/9/336/EEC) (CE Compliance))
IEC 62368
1.3 Terminology
Table 1-1 defines the acronyms, conventions, and terminology that are used
throughout the design guide.
Table 1-1: Conventions and Terminology
Acronym/Convention
/Terminology Description
ASM
Alternative Sleep Mode, ASM replaces the traditional Sleep Mode
(ACPI S3) with a new sleep mode. An example of ASM is with
Microsoft* Modern Standby* or Lucid Sleep with Google* Chrome*
AWG American Wire Gauge
BA
Declared sound power, LwAd. The declared sound power level shall
be measured according to ISO* 7779 for the power supply and
reported according to ISO 9296.
CFM Cubic Feet per Minute (airflow).

Introduction
10 Design Guide
Acronym/Convention
/Terminology Description
Monotonically A waveform changes from one level to another in a steady fashion,
without oscillation.
MTBF Mean time between failure.
Noise The periodic or random signals over frequency band of 0 Hz to 20
MHz.
Non-ASM Computers that do not use Alternative Sleep Mode use traditional
Sleep Mode (ACPI S3).
Overcurrent
A condition in which a supply attempts to provide more output
current than the amount for which it is rated. This commonly
occurs if there is a "short circuit" condition in the load attached to
the supply.
PFC Power Factor Correction.
P-P Peak to Peak Voltage Measurement.
PWR_OK
PWR_OK is a “power good” signal used by the system power
supply to indicate that the +5VDC, +3.3 VDC and +12VDC outputs
are above the under voltage thresholds of the power supply.
Ripple Noise The periodic or random signals over a frequency band of 0 Hz to
20 MHz.
Rise Time Rise time is defined as the time it takes any output voltage to rise
from 10% to 90% of its nominal voltage.
Surge The condition where the AC line voltage rises above nominal
voltage.
VSB or Standby Voltage An output voltage that is present whenever AC power is applied to
the AC inputs of the supply.
Table 1-2: Support Terminology
Category Description
Optional
The status given to items within this design guide, which are not
required to meet design guide, however, some system applications
may optionally use these features. May be a required or
recommended item in a future design guide.
Recommended
The status given to items within this design guide, which are not
required to meet design guide, however, are required by many
system applications. May be a required item in a future design guide.
Required
The status given to items within this design guide, which are
required to meet design guide and a large majority of system
applications.
§ §