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ATX Version 3.0 Multi Rail Desktop Platform Power Supply Design Guide Revision 2.0 February 2022 Document Number: 336521...
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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.
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Figure 12-3: PSU Slot Feature Detail ..................70 Figure 12-4: Recommended Chassis Tab Feature ..............71 Figure 13-1: Power Supply Dimensions for Chassis that does not Require Top Venting ....72 Figure 13-2: Power Supply Dimensions for Chassis that Require Top Venting ......73 Figure 14-1: 40 mm Profile Mechanical Outline ..............
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Revision History Document Revision Description Revision Number Number Date • Initial release of combined power supply design guide January 2006 • Combined CFX12V, LFX12V, ATX12V, SFX12V, and TFX12V content into one desktop power supply design guide • CFX12V content derived from revision 1.2 ...
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Document Revision Revision Description Number Number Date • Section updated configuration charts • Removed dates from reference documentation. Refer to the latest version available • Updated Figure 58 • Updated Section 4.2.3 Remote sensing to recommended July 2012 level • Added Section 4.2.10 12 V2DC Minimum Loading Recommendation •...
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• Sections 11, 12, 13, 14, and 16 Added form factor revision summary to beginning of each form factor specific section • Added new Intel Test Plan Section 1.41 • Update Section – Table 2-1...
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Document Revision Revision Description Number Number Date 1.42 • Update Table 2-1: 12V2 Current for Processor May 2018 Configurations. • Update Figure 4-3: Power Supply Timing. • Add Figure 4-5: +5VSB Power on timing versus VAC. • Add note Table 5-10: Serial ATA* Power Connector Pin- out: +3.3V is removed from SATA V3.2 spec.
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Document Revision Description Revision Number Number Date • Added Table 4-4: DC Output Transient Slew Rate and text describing Slew Rate • Updated Table 4-9: Power Supply Timing – Previous Required value is now Legacy Timings and Previous Recommended is now Required. •...
Introduction Introduction This document aligns to ATX Specification Version 3.0 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.
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Introduction Document Number Document /Source IEEE* Recommended Practice on Surge Voltages in Low-Voltage AC ANSI* C62.41-1991 Circuits IEEE Guide on Surge Testing for Equipment Connected to Low- ANSI C62.45-1992 Voltage AC Power Circuits EMKO-TSE (74-SEC) Nordic national requirement in addition to EN 60950 207/94 American National Standard for Methods of Measurement of Radio- Noise Emissions from Low-Voltage Electrical and Electronic...
Introduction Document Number Document /Source ENERGY STAR for Computers Version 8.0 https://www.energystar .gov/products/spec/co mputers_version_8_0_ European Union Energy Related Products(ErP) Lot 6 https://ec.europa.eu/en ergy/en/topics/energy- efficiency/energy- efficient- products/standby Power Supply Efficiency Labeling Program – 80 plus Organization 80plus.org Generalized Test Protocol for Calculating the Energy Efficiency of EPRI –...
Introduction Acronym, Convention/ Description Terminology Power Factor Correction. 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.
Processor Configurations Processor Configurations Processor Configurations - RECOMMENDED The processor power in a desktop computer is provided by the 12V2 power rail of power supplies with multiple power rails. To meet the desktop processor power needs a desktop power supply must provide the current value list in Table 2-1 for the 12V2 voltage rail.
Processor Configurations 2.2.1 Modular Power Supply Connectors A modular power supply, with multiple detachable cable options is recommended to provide the greatest flexibility to the end user. This approach reduces the chassis volume consumed by unused power cables to improve cable routing and cooling. The dedicated 12V CPU connectors on the motherboard are either a single 8 pin (2x4) connector, or one or two 4 pin (2x2) connectors, detailed in Section 5.2.2.5...
Processor Configurations connected chassis component such as a PCIe* Card or motherboard 12V CPU connector(s). For example, a standard 2x3 PCIe* power connector supporting a graphics card will draw no more than 6.75 Amps total through its three power pins and two ground pins. Similarly, the 2x4 PCIe* power connector will draw no more than 13.5 Amps total through three power pins and three ground pins.
PCI Express* Add-in Card Considerations 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.
PCI Express* Add-in Card Considerations integrated into the specification itself in upcoming releases. This ECN is titled “Power Excursion Limits for 300W-600W PCIe* AICs” (Doc# 16495). This ECN defines power excursions, which are a “temporary condition in which the power exceeds the maximum sustained power”.
PCI Express* Add-in Card Considerations Average Power Calculation Ratio of Average Power1 in Interval Length in Notes microseconds(µs) Interval “T” Divided by Maximum Sustain Power “T” ≥ 1,000,000 µs (1 sec) NOTES: average power during internal T Max Sustained Power (ie.TDP) This is also the max ratio of instantaneous power relative to maximum sustained power.
PCI Express* Add-in Card Considerations 3. Rest-of-Platform power demand Rest-of-Platform(ROP) collectively includes anything in a system (memory, storage, motherboard, peripherals, etc.) not including the PCIe Add-in Cards or CPU. Table 3-2 provides examples that generally balance these three power demands to obtain an overall PSU power rating.
PCI Express* Add-in Card Considerations If Rest of Platform power is higher than what is in the table, increase the PSU size respectively. If Rest of Platform power is lower than what is listed in the table the PSU size ...
PCI Express* Add-in Card Considerations Figure 3-2: Duty Cycle Definition Table 3-4: Duty Cycle Example Test Criteria for a 1000W PSU – RMS Time for Power Time Constant Power @ Power Duty Cycle Excursion (T 100 µs 900 µs 2000 W 817 W 1 ms 4 ms...
PCI Express* Add-in Card Considerations tolerance required to the PCIe* Add-in Card at both the motherboard edge card connector and Auxiliary Power connectors. Each Auxiliary Power Connector must have voltage pins that belong to the same +12V power converter, if multiple voltage rails exist from the PSU.
PCI Express* Add-in Card Considerations 3.3.1 Sense1 / Sense0 (Required) These two sideband signals provide important information from the PSU to the Add-in Card and are therefore required from the power supply. These signals allow the PSU to tell the Add-in Card how much power the Add-in Card can use during both Initial Power Up and Maximum Permitted Power.
PCI Express* Add-in Card Considerations The Add-in Card will set this signal to Open (high impedance) whenever its local power rails that are critical to correct operation are within their operating limits. When the Add-in Card directly drives this signal low (0 / Ground), any of its local power rails are outside of their operating limits results in a fault for the Add-in Card.
PCI Express* Add-in Card Considerations 0/1 sideband signals. If this feature is used and the SENSE 0/1 signals are dynamically changed they must be changed only when the power supply is in Standby Mode (PS_ON# is de-asserted and Main Power rails are not on). Once PS_ON# and the main power rails achieve their full voltages the SENSE 0/1 sideband signals must not be changed.
Electrical Electrical The following electrical requirements are required and must be met over the environmental ranges as defined in Chapter 7 (unless otherwise noted). AC Input - REQUIRED Table 4-1 lists AC input voltage and frequency requirements for continuous operation. The power supply shall be capable of supplying full-rated output power over two input voltage ranges rated 90-135 VAC and 180-265 VAC rms nominal.
Electrical DC Output - REQUIRED 4.2.1 DC Voltage Regulation – REQUIRED The DC output voltages are required to remain within the regulation ranges shown in Table 4-2, when measured at the load end of the output connectors under all line, load, and environmental conditions specified in Chapter 7.
Electrical Maximum Step Size Maximum Step Size Output (% of rated output amps) -12VDC +5VSB NOTES: Example of how to use this table, for a rated +5 VDC output of 14A, the transient step would be 30% x 14 A = 4.2 A. Testing for a 4.2 A step size would result in testing starting at 9.8A going up to 14A.
Electrical 4.2.3 Remote Sensing - RECOMMENDED Remote sensing is recommended. Remote sensing can accurately control motherboard loads by adding it to the PSU connector. The +3.3 VDC output should have provisions for remote sensing to compensate for excessive cable drops. In low power PSU, remote sensing is recommended.
Electrical Table 4-6: DC Output Noise/Ripple Output Maximum Ripple and Noise (mV p-p) +12V1DC +12V2DC +5VDC +3.3VDC -12VDC +5VSB Figure 4-1: Differential Noise Test Setup 4.2.6 Capacitive Load – RECOMMENDED The power supply should be able to power up and operate within the regulation limits defined in Table 4-2, with the following capacitances simultaneously present on the...
Electrical μ Output Capacitive Load ( +5VDC 3,300 +3.3VDC 3,300 -12VDC +5VSB 3,300 4.2.7 Closed Loop Stability - REQUIRED The power supply shall be unconditionally stable under all line/load/transient load conditions including capacitive loads specified in Section 4.2.6. A minimum of 45 degrees phase margin and 10 dB gain margin is recommended at both the maximum and minimum loads.
Electrical 4.2.9 Voltage Hold-Up Time - REQUIRED The power supply shall maintain output regulations per Table 4-2 despite a loss of input power at the low-end nominal range-115 VAC / 47 Hz or 230 VAC / 47 Hz – at maximum continuous output load as applicable for a minimum of 17ms (T5+T6).
Electrical Table 4-9: Power Supply Timing Value Parameter Description Recommended Legacy Timings Required for ALPM AC power on time <2s Power-on time < 500 ms < 200 ms <150 ms Rise time 0.2 – 20 ms PWR_OK delay 100 ms –...
Electrical Table 4-10: PWR_OK Signal Characteristics Signal Type +5 V TTL compatible Logic level low < 0.4 V while sinking 4 mA Logic level high Between 2.4 V and 5 V output while sourcing 200 μA High state output impedance 1 kΩ...
Electrical Parameter Minimum Maximum open circuit -5.25 V Ripple / Noise 400 mV p-p NOTES: Negative current indicates that the current is flowing from the power supply to the motherboard. Due to PS_ON# toggle on/off frequently, system and PSU component’s reliability should be considered based on the days, months, or years of claimed warranty listed on product specification.
Electrical Some scenarios like USB Power Charging in ALPM could require more current on the 5VSB rail. Figure 4-5 +5VSB Power on timing versus VAC 4.3.5 Power-On Time – REQUIRED The power-on time is defined as the time from when PS_ON# is pulled low to when the +12 VDC, +5 VDC, and +3.3 VDC outputs are within the regulation ranges specified in Table...
Electrical Figure 4-6: Rise Time Characteristics 4.3.7 Overshoot at Turn-On / Turn-Off – REQUIRED The output voltage overshoot upon the application or removal of the input voltage, or the assertion/de-assertion of PS_ON#, under the conditions specified in Table 4-2, shall be less than 10% above the nominal voltage. No voltage of opposite polarity shall be present on any output during turn-on or turn-off.
Power supply 5VSB is recommended to go down to low level within 2 seconds under any load condition after AC power is removed as shown in Figure 4-7. Intel test plan ® will test at Light 20% Load. If system requires specific +5VSB fall time, the PSU design is recommended to support it.
Electrical 4.5.2 Short Circuit Protection (SCP) – REQUIRED An output short circuit is defined as any output impedance of less than 0.1 ohms. The power supply shall shut down and latch off for shorting the +3.3V DC, +5V DC, or +12V DC rails to return or any other rail.
Electrical to meet a 240VA Energy Hazard Safety Requirement, most power supplies are not currently designed to meet this requirement. 4.5.8 Overall Power Supply Efficiency Levels The efficiency of the power supply should be tested at nominal input voltage of 115 VAC input and 230 VAC input, under the load conditions defined in the Generalized Test Protocol for Calculating the Energy Efficiency of Internal Ac-Dc and Dc-Dc Power Supplies document.
Electrical 4.5.9 Power Supply Efficiency for Energy Regulations - ENERGY STAR* and CEC (California Energy Commission) PC Computers with High Expandability Score - RECOMMENDED The efficiency of the power supply should be tested at nominal input voltage of 115 VAC input and 230 VAC input, under the load conditions defined in the form factor specific sections, and under the temperature and operating conditions defined in Chapter 7.
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Electrical *Details about High Expandability Computers definition check CEC computer regulation. The RECOMMENDED minimum efficiency levels shown in Table 4-15 are required for internal power supplies within the ENERGY STAR* for Computers Version 8.0 specification. §§ 336521...
Mechanical Mechanical This chapter contains mechanical guidelines that apply to desktop power supplies regardless of form factor. For form factor specific design guides refer to Chapter 11 through Chapter Labeling and Marking - RECOMMENDED The following is a non-inclusive list of suggested markings for each power supply unit. Product regulation stipulations for sale into various geographies may impose additional labeling requirements.
Mechanical Connectors - REQUIRED 5.2.1 AC Connector The AC input receptacle must be an IEC 320 type or equivalent. In lieu of a dedicated switch, the IEC 320 receptacle may be considered the mains disconnect. 5.2.2 DC Connectors : Main Power Connector Pin-Out Table 5-1 shows pin outs and profiles for typical power supply DC harness connectors.
Mechanical 5.2.2.1 Main Power Connector – REQUIRED Connector: Molex* Housing: 24 Pin Molex Mini-Fit Jr. PN# 39-01-2240 or equivalent. Contact: Molex 44476-1112 (HCS) or equivalent (Mating motherboard connector is Molex 44206-0007 or equivalent). 18 AWG is suggested for all wires except for the +3.3 V supply and sense return wires combined into pin 13 (22 AWG).
Mechanical Table 5-2: Peripheral Connector Pin-out Signal Color +12V1 DC Yellow Black Black +5 VDC NOTE: 18 AWG wire. 5.2.2.3 Floppy Drive Connector – Do Not Include (For Historical Reference Only) Connector: AMP* 171822-4 or equivalent. Table 5-3: Floppy Connector Pin-out Signal Color +5V DC...
Mechanical • Pin Contact Base Material: Brass alloy or equivalent • Pin Contact Plating: Sn alloy • Flammability: UL94V-1 Minimum - Material certification or certificate of compliance is required with each lot to satisfy the Underwriters Laboratories follow-up service requirements. •...
Mechanical • Flammability: UL94V-1 Minimum - Material certification or certificate of compliance is required with each lot to satisfy the Underwriters Laboratories follow-up service requirements. • Lead Free Soldering: Connector must be compatible with lead free soldering process Table 5-5: PCIe* 2x4 Auxiliary Power Connector Pin Assignment (150 Watts) Signal Color Signal...
Mechanical Figure 5-4: 12VHPWR Cable Assembly The cable plug connector housing for the 12VHPWR connector has all dimensions shown in mm. Slight changes to this connector that does not affect matting with its associated plug may happen. Reference latest PCI-SIG documentation for latest information about this connector.
Mechanical • Signal Pin Contact Plating: Tin plated on contact area • All dimensions are in mm • Connector must be compatible with lead-free soldering process. Wire Details: • Power/Ground Pin Wire Size: 16 AWG All 12 pins must be connected to the power supply using 16 AWG cable •...
Mechanical Table 5-9: +12 V Power 8 pin Connector Pin-Out Signal Color Signal Color Black +12V2 DC Yellow Black +12V2 DC Yellow Black +12V2 DC Yellow Black +12V2 DC Yellow NOTE: 18 AWG wire. 5.2.2.6 Serial ATA* Connectors – REQUIRED This is a required connector for systems with Serial ATA devices.
Mechanical Figure 5-5: Serial ATA* Power Connector Airflow and Fans - RECOMMENDED The designer's choice of a power supply cooling solution depends in part on the targeted end-use system application(s). At a minimum, the power supply design should ensure its own reliable and safe operation. 5.3.1 Fan Location and Direction In general, exhausting air from the system chassis enclosure via a power supply fan...
Mechanical 5.3.3 Venting In general, more venting in a power supply case yields reduced airflow impedance and improved cooling performance. Intake and exhaust vents should be large, open, and unobstructed as possible so as not to impede airflow or generate excessive acoustic noise.
Acoustics Acoustics Acoustics – RECOMMENDED It is recommended that the power supply be designed with an appropriate fan, internal impedance, and fan speed control circuitry capable of meeting the acoustic targets listed in Table 6-1: Recommended Power Supply Acoustic Targets. The power supply assembly should not produce, and prominent discrete tone determined according to ISO 7779, Annex D.
Environmental Environmental The following subsections define environmental specifications and test parameters, based on the typical conditions to which a power supply may be subjected during operation or shipment. Temperature – RECOMMENDED • Operating ambient +10 °C to +50 °C (At full load, with a maximum temperature rate of change of 5 °C/10 minutes, but no more than 10 °C/hr.) •...
Environmental Random Vibration – RECOMMENDED • Non-operating 0.01 g²/Hz at 5 Hz, sloping to 0.02 g²/Hz at 20 Hz, and maintaining 0.02 g²/Hz from 20 Hz to 500 Hz. The area under the PSD curve is 3.13 gRMS. The duration shall be 10 minutes per axis for all three axes on all samples. §§...
Electromagnetic Compatibility Electromagnetic Compatibility The following subsections outline applicable product regulatory requirements for the power supplies. Additional requirements may apply dependent upon the design, product end use, target geography, and other variables. Emissions – REQUIRED The power supply shall comply with FCC Part 15, EN55023 and CISPR 22, 5th ed., meeting Class B for both conducted and radiated emissions with a 4 dB margin.
Electromagnetic Compatibility Voltage Fluctuations and Flicker – REQUIRED The power supply shall meet the specified limits of EN61000-3-3 (IEC 61000-3-3) and amendment A1 to EN 61000-3-3 (IEC 61000-3-3/A1) for voltage fluctuations and flicker for equipment drawing not more than 16VAC, connected to low voltage distribution systems.
Safety Safety The following subsections outline sample product regulations requirements for a typical power supply. Actual requirements will depend on the design, product end use, target geography, and other variables. Consult your company’s Product Safety and Regulations department or an accredited third-party certification agency for more details.
Safety The power supply must meet the RoHS requirements for the European Union, Peoples Republic of China and other countries which have adopted the RoHS requirements for banned materials. Proscribed Materials - REQUIRED The following materials must not be used during design and/or manufacturing of this product: Cadmium shall not be used in painting or plating - REQUIRED.
Reliability – PS_ON# toggle for S0ix mode - REQUIRED In order to optimize desktop platform power consumption, Intel provides design recommendation to enable PSU PS_ON# toggle on/off during S0 idle power mode (S0ix) to save both system and PSU power. The PSU PS_ON# may toggle on/off every...
CFX12V Specific Guidelines 2.0 CFX12V Specific Guidelines 2.0 For Compact Form Factor with 12-volt connector power supplies. All Form Factors Revision Summary: PSU DG CFX12V LFX12V ATX12V SFX12V TFX12V Flex ATX 11.1 Physical Dimensions – REQUIRED The power supply shall be enclosed and meet the physical outline shown. Figure 11-1: CFX12V Mechanical Outline §§...
LFX12V Specific Guidelines 2.0 LFX12V Specific Guidelines 2.0 For Low Profile Form Factor with 12-volt connector power supplies. All Form Factors Revision Summary: PSU DG CFX12V LFX12V ATX12V SFX12V TFX12V Flex ATX 12.1 Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 12-1, applicable.
ATX12V Specific Guidelines 3.0 ATX12V Specific Guidelines 3.0 For ATX Form Factor with 12-volt connector power supplies. All Form Factors Revision Summary: PSU DG CFX12V LFX12V ATX12V SFX12V TFX12V Flex ATX Figure 13-1: Power Supply Dimensions for Chassis that does not Require Top Venting 336521...
SFX12V Specific Guidelines 4.0 SFX12V Specific Guidelines 4.0 For Small Form Factor with 12-volt connector power supplies. All Form Factors Revision Summary: PSU DG CFX12V LFX12V ATX12V SFX12V TFX12V Flex ATX 14.1 Lower Profile Package - Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 14-1.
SFX12V Specific Guidelines 4.0 14.3 Top Fan Mount Package - Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 14-3. 14.4 Fan Requirements - REQUIRED The fan will draw air from the computer system cavity pressurizing the power supply enclosure.
SFX12V Specific Guidelines 4.0 Figure 14-4: Chassis Cutout Figure 14-5: Recessed Fan Mounting 14.5 Reduced Depth Top Mount Fan - Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 14-6. 14.6 Fan Requirements - REQUIRED The fan will draw air from the computer system cavity pressurizing the power supply enclosure.
SFX12V Specific Guidelines 4.0 14.7 Standard SFX Profile Package – Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 14-8. 14.8 Fan Requirements - REQUIRED The fan will draw air from the computer system cavity pressurizing the power supply enclosure.
SFX12V Specific Guidelines 4.0 Figure 14-9: Chassis Cutout 14.9 PS3 Form Factor-Physical Dimensions - REQUIRED The power supply shall be enclosed and meet the physical outline shown in Figure 14-10. 14.10 Fan Requirements - REQUIRED An 80 mm axial fan is typically needed to provide enough cooling airflow through a high performance Micro ATX system.
TFX12V Specific Guidelines 3.0 Figure 15-3: Power Supply Mounting Slot Detail 15.2 Mounting Options - RECOMMENDED The TFX12V mechanical design provides two options for mounting in a system chassis. The unit can be mounted using one of the mounting holes on the front end (non- vented end) or a chassis feature can be designed to engage the slot provided in the bottom of the supply.
TFX12V Specific Guidelines 3.0 orientation as shown in Figure 15-2. Details of a suggested geometry for the mounting slot are shown in Figure 15-3. Figure 15-4: Fan Right and Fan Left Orientations of Power Supply in a Chassis 15.3 Chassis Requirements - RECOMMENDED To ensure the power supply can be easily integrated, the following features should be designed into a chassis intended to use a TFX12V power supply: •...
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