Intel ATX 0.9 User Manual
Intel ATX Power Supply Design Guide
Version 0.9
Intel ATX Power Supply Design Guide
Version 0.9
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Copyright 1998 Intel Corporation. All rights reserved.
Version 0.9, Septem ber 1998
†
Third-party brands and names are the property of t hei r respective owners.
Revision History
0.9 Initial Release
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Intel ATX Power Supply Design Guide
Version 0.9
Contents
1. Scope.................................................................................................................. 6
2. Applicable Documents...................................................................................... 7
3. Electrical Specification .....................................................................................8
3.1 AC Input Requirements .........................................................................................................8
3.1.1 Input Overcurrent Protection.....................................................................................8
3.1.2 Inrush Current Limiting .............................................................................................8
3.1.3 Input Undervoltage ...................................................................................................8
3.1.4 Immunity...................................................................................................................9
3.1.5 Catastrophic Failure Protection ................................................................................11
3.2 DC Output Requirements ......................................................................................................11
3.2.1 DC Voltage Regulation .............................................................................................11
3.2.2 Remote Sensing.......................................................................................................11
3.3 Typical Power Distribution.....................................................................................................12
3.3.1 Power Limit...............................................................................................................13
3.3.2 Efficiency ..................................................................................................................13
3.3.3 Output Ripple/Noise..................................................................................................14
3.3.4 Output Transient Response......................................................................................14
3.3.5 Capacitive Load........................................................................................................14
3.3.6 Closed Loop Stability................................................................................................14
3.3.7 +5VDC/+3.3VDC Power Sequencing .......................................................................15
3.3.8 Voltage Hold-up Time...............................................................................................15
3.4 Timing / Housekeeping / Control...........................................................................................16
3.4.1 PWR_OK..................................................................................................................16
3.4.2 PS_ON#....................................................................................................................17
3.4.3 +5VSB.......................................................................................................................17
3.4.4 Power-on Time .........................................................................................................17
3.4.5 Risetime....................................................................................................................18
3.4.6 Overshoot at Turn-on/Turn-off..................................................................................18
3.4.7 Reset after Shutdown ...............................................................................................18
3.4.8 +5VSB at AC Power Down .......................................................................................18
3.5 Output Protection...................................................................................................................19
3.5.1 Overvoltage Protection .............................................................................................19
3.5.2 Short Circuit Protection.............................................................................................19
3.5.3 No Load Operation ...................................................................................................19
3.5.4 Overcurrent Protection..............................................................................................19
3.5.5 Output Bypass ..........................................................................................................19
4. Mechanical Requirements ................................................................................ 20
4.1 Labeling / Marking .................................................................................................................20
4.2 Physical Dimensions..............................................................................................................20
4.3 Airflow / Fan...........................................................................................................................23
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4.4 AC Connector........................................................................................................................23
4.5 DC Connectors......................................................................................................................23
4.5.1 ATX Main Power Connector .....................................................................................24
4.5.2 Auxiliary Power Connector (for 250 W and 300 W Configurations) .........................25
4.5.3 Peripheral Connector(s)............................................................................................25
4.5.4 Floppy Drive Connector............................................................................................25
5. Environmental Requirements...........................................................................26
5.1 Temperature..........................................................................................................................26
5.2 Thermal Shock (Shipping).....................................................................................................26
5.3 Humidity.................................................................................................................................26
5.4 Altitude...................................................................................................................................26
5.5 Mechanical Shock .................................................................................................................26
5.6 Random Vibration..................................................................................................................27
5.7 Acoustics ...............................................................................................................................27
6. Electromagnetic Compatibility......................................................................... 28
6.1 EMI ........................................................................................................................................28
6.2 Input Line Current Harmonic Content (Optional)...................................................................28
6.3 Magnetic Leakage Fields.......................................................................................................28
7. Reliability............................................................................................................ 29
7.1 Component Derating .............................................................................................................29
7.2 Mean Time Between Failures (MTBF)...................................................................................29
8. Safety Requirements......................................................................................... 30
8.1 North America........................................................................................................................30
8.2 International...........................................................................................................................31
8.3 Proscribed Materials..............................................................................................................31
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Intel ATX Power Supply Design Guide
Version 0.9
Figures
Figure 1: Power Supply Timing.............................................................................................................16
Figure 2: Power Supply Dimensions for Chassis in Which the P/S Does Not Cool Processor ............21
Figure 3: Power Supply Dimensions for Chassis in Which the P/S Cools the Processor.....................22
Figure 4: ATX Power Supply Connectors .............................................................................................24
Tables
Table 1: AC Input Line Requirements...................................................................................................8
Table 2: AC Line Voltage Transient Limits............................................................................................9
Table 3: DC Output Voltage Regulation................................................................................................11
Table 4: Typical Power Distribution for a 160 W Configuration ............................................................12
Table 5: Typical Power Distribution for a 200 W Configuration ............................................................12
Table 6: Typical Power Distribution for a 250 W Configuration ............................................................13
Table 7: Typical Power Distribution for a 300 W Configuration ............................................................13
Table 8: DC Output Noise/Ripple..........................................................................................................14
Table 9: PWR_OK Signal Characteristics ............................................................................................16
Table 10: PS_ON# Signal Characteristics ............................................................................................17
Table 11: Overvoltage Protection..........................................................................................................19
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Intel ATX Power Supply Design Guide
Version 0.9
1. Scope
This document outlines a reference ATX power supply that complies with the ATX
Specification, Version 2.02 for motherboards and chassis. It is intended to provide
additional power supply design information not detailed in the ATX 2.02 specification,
including information about the physical form factor of the power supply, cooling
requirements, connector configuration, and pertinent electrical and signal timing
specifications.
This document is provided as a convenience only and is not intended to replace or
supplement the user’s independent design and validation activity. It should not be inferred
that all ATX power supplies must conform exactly to the content of this document. Neither
are the design specifics described herein intended to support all possible system
configurations, as system power supply needs will vary widely depending on application
(desktop / workstation / server), intended ambient environment (temperature, line voltage),
motherboard power requirements, etc.
With a few modifications, a standard PS/2† power supply can support an ATX form-factor
system. At a high level, these modifications include consolidating various motherboard
connectors into a single 20-pin connector, adding +3.3VDC and +5VSB output supply
rails, adding a PS_ON# control input, and possibly repositioning the fan and/or venting
locations.
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Intel ATX Power Supply Design Guide
Version 0.9
2. Applicable Documents
The latest revision in effect of the following documents forms a part of this document to the
extent specified.
AB13-94-146 EACEM European Association of Consumer Electronics Manufacturers.
Hazardous Substance List / Certification.
ANSI C62.41-1991 IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Circuits.
ANSI C62.45-1992 IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC
Power Circuits.
MIL-STD-105K Quality Control.
MIL-STD-217F Reliability Predictions for Electronic Equipment.
MIL-C-5541 Chemical Conversion Coatings on Aluminum and Aluminum Alloys.
CSA C22.2 No.234, Level 3 Safety of Component Power Supplies. Intended for use with Electronic Data
Processing Equipment and Office Machines.
CAN/CSA C22.2 No.950-95,
rd
edition
3
UL 1950 without D3 Deviation,
rd
edition
3
IEC 950 plus A1, A2, A3, A4 Safety of Information Technology Equipment including Business Equipment.
EN60 950 plus A1, A2, A3, A4 Safety of Information Technology Equipment including Business Equipment.
EMKO-TSE (74-SEC) 207/94 Nordic National Requirement in addition to EN60950.
CISPR 22 and EN 55022 Limits and Methods of Measurements of Radio Interference Characteristics of
ANSI C63.4 – 1992 American National Standard for Methods of Measurement of Radio-Noise
EN50082-1 (1992) Electromagnetic compatibility/generic immunity standard.
EN61000-3-2 Limits for Harmonic Current Emission, Class D.
Japan Electric Association Guidelines for the Suppression of Harmonics in Appliances and General Use
IEC801- / IEC1000-4- Electromagnetic compatibility for industrial-process measurement and control
IEC Publication 417 International Graphic Symbol Standard.
ISO Standard 7000 Graphic Symbols for Use on Equipment.
CFR 47, Part 15, Subpart B FCC Rules.
PrEN 50082-1: 1995 Electromagnetic compatibility, generic immunity.
ENV 50140 Radio frequency electromagnetic field test standard, Amplitude modulated.
ENV 50204 Radio frequency electromagnetic field-test standard, Keyed carrier.
ENV 50141 Radio frequency common mode test standard.
EN 61000-4-11 Voltage dips and interruptions test standard.
Safety of Information Technology Equipment including Electrical Business
Equipment.
Safety of Information Technology Equipment including Electrical Business
Equipment.
Information Technology Equipment, Class B.
Emissions from Low-Voltage Electrical and Electronic Equipment in the
Range of 9 kHz to 40 GHz for EMI testing.
Equipment.
equipment.
Part -2: ESD Requirements.
Part -3: Immunity to Radiated Electromagnetic Fields.
Part -4: Electrical Fast Transients/Burst Requirements.
Part -5: Surge Immunity Requirements.
Standard, Part 1: Residential, commercial and light industry.
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Intel ATX Power Supply Design Guide
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3. Electrical Specification
The electrical requirements that follow are to be met over the environmental ranges
specified in Section 5 unless otherwise noted.
3.1 AC Input Requirements
The power supply shall be capable of supplying full rated output power over two input
voltage ranges rated 100-127 VAC and 200-240 VAC RMS nominal. The correct input
range for use in a given environment may be either switch-selectable or auto-ranging. The
power supply shall automatically recover from AC power loss. The input voltage, current,
and frequency requirements for continuous operation are stated below. (Note that nominal
voltages for test purposes are considered to be within ±1.0 V of nominal.) The power
supply must be able to start up under peak loading at 90 VAC.
Table 1: AC Input Line Requirements
Parameter Min Nom Max Unit
Vin (115 VAC) 90 115 135 VAC
Vin (230 VAC) 180 230 265 VAC
Vin Frequency 47 -- 63 Hz
Iin (115 VAC) 7.0 A
Iin (230 VAC) 3.5 A
rms
rms
rms
rms
3.1.1 Input Overcurrent Protection
The power supply shall incorporate primary fusing for input overcurrent protection. Fuses
should be slow-blow type or equivalent to prevent nuisance trips.
3.1.2 Inrush Current Limiting
Maximum inrush current from power-on (with power on at any point on the AC Sine) and
including, but not limited to, three line cycles, shall be limited to a level below the surge
rating of the input line cord, AC switch if present, bridge rectifier, fuse, and EMI filter
components. Repetitive ON/OFF cycling of the AC input voltage should not damage the
power supply or cause the input fuse to blow.
3.1.3 Input Undervoltage
The power supply shall contain protection circuitry such that the application of an input
voltage below the minimum specified in Section 3.1, Table 1, shall not cause damage to the
power supply.
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Intel ATX Power Supply Design Guide
3.1.4 Immunity
3.1.4.1 Slow Transients
The DC output(s) shall not exceed the limits specified in Section 3.2.1 as a result of the
input power line noise defined in Table 2 under any load condition per EN 61000-4-11.
Table 2: AC Line Voltage Transient Limits
Version 0.9
Duration Sag /
Surge
0 to 500 ms 10% Rated AC voltages 50/60 Hz No loss of function or
0 to 15
minutes
0 to ½ AC
cycle
0 to 5 AC
cycles
15% Mid-point of rated AC
30% Mid-point of rated AC
50%
sag only
Operating AC Voltage Line
Frequency
50/60 Hz No loss of function or
voltages
50/60 Hz No loss of function or
voltages
Mid-point of rated AC
voltages
50/60 Hz Loss of function acceptable,
Performance Criteria
performance
performance
performance
self- recoverable
3.1.4.2 Surge Voltages
Input Surge Withstand Capability (Line Transients). The power supply shall meet the
IEC801-5/IEC 1000-4-5 Level 1, Level 2, and Level 3 criteria for surge withstand
capability, with the following conditions and exceptions. The power supply must meet the
surge withstand test for the range of operation specified in Section 3.1.
The peak value of the injected unipolar wave form shall be 2.0 kV measured at the input of
the power supply for the common and the normal modes of transient surge injection.
The surge withstand test must not produce:
• Damage to the power supply
• Disruption of the normal operation of the power supply
• Output voltage deviation exceeding the limits of Section 3.2.1.
3.1.4.2.1 Surge Immunity, IEC801-5/IEC1000-4-5
No unsafe operation is allowed under any condition. No user-noticeable performance
degradation for 1 kV Differential Mode (DM) or 2 kV Common Mode (CM) is allowed.
Automatic or manual recovery is allowed for other conditions.
3.1.4.2.2 Electrical Fast Transient / Burst, IEC801-4/IEC1000-4-4
No unsafe operation is allowed under any condition. No user-noticeable performance
degradation up to 1 kV is allowed. Automatic or manual recovery is allowed for other
conditions.
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3.1.4.2.3 Ring Wave, ANSI C62.45-1992
The crest value of the first half peak of the injected oscillatory wave will be 3.0 kV open
circuit, with 200 and 500 A short circuit currents for the common and the normal modes of
transient surge injection, respectively. No unsafe operation is allowed under any condition.
No user-noticeable performance degradation for 1 kV Differential Mode (DM) or 2 kV
Common Mode (CM) is allowed. Automatic or manual recovery is allowed for other
conditions.
3.1.4.2.4 Electrostatic Discharge, IEC801-2/IEC1000-4-2
In addition to IEC 801-2 / IEC1000-4-2, the following ESD tests should be conducted.
Each surface area of the unit under test should be subjected to twenty (20) successive static
discharges, at each of the following voltages: 2 kV, 3 kV, 4 kV, 5 kV, 6 kV, 8 kV, 10 kV,
15 kV, and 25 kV.
Performance criteria:
• All power supply outputs shall continue to operate within the parameters of this design
guide, without glitches or interruption, while the supply is operating as defined and
subjected to 2 kV through 15 kV ESD pulses. The direct ESD event shall not cause any
out-of-regulation conditions such as overshoot or undershoot. The power system shall
withstand these shocks without nuisance trips of the overvoltage protection, overcurrent
protection, or remote +5VDC shutdown circuitry.
• The power supply, while operating as defined, shall not have a component failure when
subjected to any discharge voltages up to and including 25 kV. Component failure is
defined as any malfunction of the power supply that causes component degradation or
failure requiring component replacement to correct the problem.
3.1.4.3 Radiated Immunity
3.1.4.3.1 IEC801-3/IEC 1000-4-3
Frequency Electric Field Strength
27 MHz to 500 MHz, unmodulated 3 V/m
3.1.4.3.2 ENV 50140
Frequency Electric Field Strength
80 to 1000 MHz, 1 kHz sine wave, 80% AM 3 V/m
3.1.4.3.3 Radio Frequency Common Mode, ENV 50141
Frequency Level
.15 to 30 MHz, 1 kHz sine wave, 80% AM 3 V
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