Intel Smoke Alarm 09 User Manual

Intel ATX  
Power Supply Design Guide  
Version 0.9  
 
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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Intel ATX Power Supply Design Guide  
Version 0.9  
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/2power 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  
ANSI C62.45-1992  
IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Circuits.  
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.  
Chemical Conversion Coatings on Aluminum and Aluminum Alloys.  
MIL-C-5541  
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,  
3
Safety of Information Technology Equipment including Electrical Business  
Equipment.  
rd edition  
UL 1950 without D3 Deviation,  
rd edition  
Safety of Information Technology Equipment including Electrical Business  
Equipment.  
3
IEC 950 plus A1, A2, A3, A4  
EN60 950 plus A1, A2, A3, A4  
EMKO-TSE (74-SEC) 207/94  
CISPR 22 and EN 55022  
Safety of Information Technology Equipment including Business Equipment.  
Safety of Information Technology Equipment including Business Equipment.  
Nordic National Requirement in addition to EN60950.  
Limits and Methods of Measurements of Radio Interference Characteristics of  
Information Technology Equipment, Class B.  
ANSI C63.4 – 1992  
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.  
EN50082-1 (1992)  
EN61000-3-2  
Electromagnetic compatibility/generic immunity standard.  
Limits for Harmonic Current Emission, Class D.  
Japan Electric Association  
Guidelines for the Suppression of Harmonics in Appliances and General Use  
Equipment.  
IEC801- / IEC1000-4-  
Electromagnetic compatibility for industrial-process measurement and control  
equipment.  
Part -2: ESD Requirements.  
Part -3: Immunity to Radiated Electromagnetic Fields.  
Part -4: Electrical Fast Transients/Burst Requirements.  
Part -5: Surge Immunity Requirements.  
IEC Publication 417  
International Graphic Symbol Standard.  
Graphic Symbols for Use on Equipment.  
FCC Rules.  
ISO Standard 7000  
CFR 47, Part 15, Subpart B  
PrEN 50082-1: 1995  
Electromagnetic compatibility, generic immunity.  
Standard, Part 1: Residential, commercial and light industry.  
ENV 50140  
ENV 50204  
ENV 50141  
EN 61000-4-11  
Radio frequency electromagnetic field test standard, Amplitude modulated.  
Radio frequency electromagnetic field-test standard, Keyed carrier.  
Radio frequency common mode test standard.  
Voltage dips and interruptions test standard.  
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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)  
Vin (230 VAC)  
Vin Frequency  
90  
115  
230  
--  
135  
265  
63  
VACrms  
VACrms  
Hz  
180  
47  
Iin (115 VAC)  
Iin (230 VAC)  
7.0  
3.5  
Arms  
Arms  
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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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  
Duration  
Sag /  
Operating AC Voltage  
Line  
Performance Criteria  
Surge  
Frequency  
0 to 500 ms  
10%  
15%  
30%  
50%  
Rated AC voltages  
50/60 Hz  
50/60 Hz  
50/60 Hz  
50/60 Hz  
No loss of function or  
performance  
0 to 15  
minutes  
Mid-point of rated AC  
voltages  
No loss of function or  
performance  
0 to ½ AC  
cycle  
Mid-point of rated AC  
voltages  
No loss of function or  
performance  
0 to 5 AC  
cycles  
Mid-point of rated AC  
Loss of function acceptable,  
self- recoverable  
sag only voltages  
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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Intel ATX Power Supply Design Guide  
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3.1.5 Catastrophic Failure Protection  
The primary circuit design and the components specified in the same should be such that,  
should a component failure occur, the power supply should not exhibit any of the  
following:  
Flame  
Excessive smoke  
Charred PCB  
Fused PCB conductor  
Startling noise.  
3.2 DC Output Requirements  
3.2.1 DC Voltage Regulation  
The DC output voltages shall remain within the regulation ranges shown in Table 3 when  
measured at the load end of the output connectors under all line, load, and environmental  
conditions. The voltage regulation limits shall be maintained under continuous operation  
for a period of time equal to or greater than the MTBF specified in Section 7.2 at any steady  
state temperature and operating conditions specified in Section 5.  
Table 3: DC Output Voltage Regulation  
Output  
Range  
Min.  
Nom.  
Max.  
Unit  
+12VDC*  
+5VDC  
+3.3VDC  
-5VDC  
±5%  
±5%  
+11.40  
+4.75  
+3.14  
-4.50  
+12.00  
+5.00  
+3.30  
-5.00  
+12.60  
+5.25  
+3.47  
-5.50  
Volts  
Volts  
Volts  
Volts  
Volts  
Volts  
±5%  
±10%  
±10%  
±5%  
-12VDC  
+5VSB  
-10.80  
+4.75  
-12.00  
+5.00  
-13.20  
+5.25  
* At +12 V peak loading, regulation at the +12VDC output can go to ±10%.  
3.2.2 Remote Sensing  
The +3.3VDC output should have provisions for remote sensing to compensate for 100 mV  
of cable, connector, and PCB trace drops. The default sense should be connected to pin 11  
of the ATX main power connector. The power supply should draw no more than 10 mA  
through the remote sense line to keep DC offset voltages to a minimum.  
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Intel ATX Power Supply Design Guide  
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3.3 Typical Power Distribution  
Although power requirements and distributions will depend on the specific system options  
and implementation, this section identifies several potential configurations. For a single  
processor mini-tower configuration with one ISA slot, three PCI slots, one shared slot, and  
six peripheral bays, a minimum 160 W sustained (200 W peak) power supply should be  
sufficient for a typical application. For a full tower, dual processor configuration with one  
ISA slot, five PCI slots, one shared slot, and six peripheral bays, a 300 W sustained power  
supply should be sufficient. Tables 4, 5, 6, and 7 list the suggested power distribution for  
various configurations and applications.  
Table 4: Typical Power Distribution for a 160 W Configuration  
Min.  
Max.  
Peak  
Current  
(amps)  
Current  
(amps)  
Current  
(amps)  
Output  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
Notes:  
0.0  
1.0  
0.3  
0.0  
0.0  
0.0  
6.0  
18.0  
14.0  
0.3  
8.0  
+3.3VDC and +5VDC combined power 110 W max  
Pin 11 default +3.3 V sense required  
-12VDC  
+5VSB  
0.8  
0.72  
See Section 3.4.3.  
Table 5: Typical Power Distribution for a 200 W Configuration  
Min.  
Max.  
Peak  
Current  
(amps)  
Current  
(amps)  
Current  
(amps)  
Output  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
Notes:  
0.0  
1.0  
0.3  
0.0  
0.0  
0.0  
6.0  
21.0  
14.0  
0.3  
8.0  
+3.3VDC and +5VDC combined power 125 W Max  
Pin 11 default +3.3 V sense required  
-12VDC  
+5VSB  
0.8  
0.72  
See Section 3.4.3.  
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Intel ATX Power Supply Design Guide  
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Table 6: Typical Power Distribution for a 250 W Configuration  
Min.  
Max.  
Peak  
Notes:  
Current  
(amps)  
Current  
(amps)  
Current  
(amps)  
Requires the 1x6 auxiliary power connector to carry  
the 3.3 V & 5 V currents to the PCB.  
Output  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
0.0  
1.0  
0.3  
0.0  
0.0  
0.0  
10.0  
25.0  
16.0  
0.3  
12.0  
+3.3VDC and +5VDC combined power 145 W Max  
Pin 11 default +3.3 V sense required  
-12VDC  
+5VSB  
0.8  
0.72  
See Section 3.4.3.  
Table 7: Typical Power Distribution for a 300 W Configuration  
Min.  
Max.  
Peak  
Notes:  
Current  
(amps)  
Current  
(amps)  
Current  
(amps)  
Requires the 1x6 auxiliary power connector to carry  
the 3.3 V & 5 V currents to the PCB.  
Output  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
0.0  
1.0  
0.3  
0.0  
0.0  
0.0  
10.0  
30.0  
28.0  
0.3  
12.0  
+3.3VDC and +5VDC combined power 220 W Max  
Pin 11 default +3.3 V sense required  
-12VDC  
+5VSB  
0.8  
0.72  
See Section 3.4.3.  
3.3.1 Power Limit  
Under short circuit or overload conditions, no output shall exceed 240 VA under any  
conditions including single component fault conditions.  
3.3.2 Efficiency  
The efficiency of the power supply should be met over the AC input range defined in  
Table 1, under the load conditions defined in Section 3.3, and under the temperature and  
operating conditions defined in Section 5. The power supply should be a minimum of 68%  
efficient under maximum load as defined in the applicable configuration.  
The “Energy Star” efficiency of the power supply should be a minimum of 56%. In the  
Energy Star state, the AC input power is limited to 15% of rated output power for the  
configuration. For example, in a 200 W configuration, the Energy Star input power limit is  
200 W × 0.15 = 30 W. In a 300 W configuration, the Energy Star input power is limited to  
300 W × 0.15 = 45 W.  
The +5VSB standby supply efficiency should be 50% at 500 mA output. Standby  
efficiency is measured with the main outputs off and with PS_ON# high. The AC input  
power shall not exceed 5 W when the main outputs are in the “DC disabled” state with 500  
mA load on +5VSB and the input is 230 VAC/50 Hz.  
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3.3.3 Output Ripple/Noise  
The following output ripple/noise requirements should be met throughout the load ranges  
specified in Section 3.3, and under all input voltage conditions as specified in Section 3.1.  
Ripple and noise are defined as periodic or random signals over a frequency band of 10 Hz  
to 20 MHz. Measurements shall be made with an oscilloscope with 20 MHz bandwidth.  
Outputs should be bypassed at the connector with a 0.1 µF ceramic disk capacitor and a  
10 µF electrolytic capacitor to simulate system loading.  
Table 8: DC Output Noise/Ripple  
Output  
Max Ripple & Noise  
(mVpp)  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
120  
50  
50  
100  
120  
50  
-12VDC  
+5VSB  
3.3.4 Output Transient Response  
The +3.3VDC and +5VDC outputs will see transients up to 30% of the rated output current  
(e.g., for a rated +5VDC output of 18 A, the transient step would be 0.3 × 18 A = 5.4 A).  
The +12VDC output will see transients up to 50% of the rated output current. The transient  
slew rate will be 2.5 A/µs. The power supply should be stable under all transient  
conditions from any steady state load, and the over/undershoot should be within the  
regulation band stated in Section 3.2.1.  
3.3.5 Capacitive Load  
The power supply should be able to power up and operate normally with the following  
capacitances simultaneously present on the DC outputs.  
Output:  
+12VDC  
+5VDC  
+3.3VDC  
-5VDC  
-12VDC  
+5VSB  
1,000  
10,000  
6,000  
350  
350  
350  
Capacitive load (µF):  
3.3.6 Closed Loop Stability  
The power supply shall be unconditionally stable under all line/load/transient load  
conditions including capacitive loads specified in Section 3.3.5. A minimum of 45 degrees  
phase and 10 dB-gain margin is required. The power supply vendor shall provide proof of  
the unit’s closed-loop stability with local sensing through the submission of Bode plots.  
Closed-loop stability must be ensured at the maximum and minimum loads as applicable.  
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3.3.7 +5VDC/+3.3VDC Power Sequencing  
The +5VDC output level must be equal to or greater than the +3.3VDC output at all times  
during power-up and normal operation. The time between the +5VDC output reaching its  
minimum in-regulation level and +3.3VDC reaching its minimum in-regulation level must  
be less than or equal to 20 ms.  
3.3.8 Voltage Hold-up Time  
The power supply shall maintain output regulation per Section 3.2.1 despite a loss of input  
power at the low-end nominal range (Low = 115 VAC, 57 Hz or 230 VAC, 47 Hz) at  
maximum continuous output load as applicable for a minimum of 17 ms.  
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3.4 Timing / Housekeeping / Control  
Off  
PS_ON#  
~
~
On  
95%  
+5VDC/+3.3VDC O/P 10%  
T5  
~
PWR_OK  
T3  
T2  
T4  
PWR_OK Sense Level = 95% of nominal  
Figure 1: Power Supply Timing  
Notes:  
T2 is defined in Section 3.4.5.  
T3, T4, and T5 are defined in Table 9.  
3.4.1 PWR_OK  
PWR_OK is a “power good” signal. It should be asserted high by the power supply to  
indicate that the +5VDC and +3.3VDC outputs are above the undervoltage thresholds listed  
in Section 3.2.1 and that sufficient mains energy is stored by the converter to guarantee  
continuous power operation within specification for at least the duration specified in  
Section 3.3.8. Conversely, PWR_OK should be deasserted to a low state when either the  
+5VDC or the +3.3VDC output voltages falls below the undervoltage threshold, or when  
mains power has been removed for a time sufficiently long such that power supply  
operation cannot be guaranteed beyond the hold-up time. The electrical and timing  
characteristics of the PWR_OK signal are given in Table 9 and in Figure 1.  
Table 9: PWR_OK Signal Characteristics  
Signal Type  
+5 V TTL compatible  
Logic level low  
< 0.4 V while sinking 4 mA  
Between 2.4 VDC and 5 VDC output while sourcing 200 µA  
1Kfrom output to common  
100 ms < T3 < 500 ms  
Logic level high  
High state output impedance  
PWR_OK delay  
PWR_OK rise time  
T5 10 ms  
Power down warning  
T4 > 1 ms  
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3.4.2 PS_ON#  
PS_ON# is an active-low, TTL-compatible signal that allows a motherboard to remotely  
control the power supply in conjunction with features such as soft on/off, wake-on-LAN, or  
wake-on-modem. When PS_ON# is pulled to TTL low, the power supply should turn on  
the five main DC output rails: +12VDC, +5VDC, +3.3VDC, -5VDC, and -12VDC. When  
PS_ON# is pulled to TTL high or open circuited, the DC output rails should not deliver  
current and should be held at zero potential with respect to ground. PS_ON# has no effect  
on the +5VSB output, which is always enabled whenever the AC power is present.  
The power supply shall provide an internal pull-up to TTL high. The power supply shall  
also provide debounce circuitry on PS_ON# to prevent it from oscillating on/off at startup  
due to activation by a mechanical switch. The DC output enable circuitry must be SELV-  
compliant.  
Table 10: PS_ON# Signal Characteristics  
Min.  
Max.  
VIL, Input Low Voltage  
0.0 V  
0.8 V  
IIL, Input Low Current, Vin = 0.4 V  
VIH, Input High Voltage, Iin = -200 µA  
VIH open circuit, Iin = 0  
-1.6 mA  
2.0 V  
5.25 V  
3.4.3 +5VSB  
+5VSB is a “standby” supply output that is active whenever the AC power is present. It  
provides a power source for circuits that must remain operational when the five main DC  
output rails are in a disabled state. Example uses include soft power control, wake-on-  
LAN, wake-on-modem, intrusion detection, or suspend state activities. +5VSB is required  
for the implementation of PS_ON#.  
The +5VSB output should be capable of delivering a minimum of 720 mA at +5 V ±5% to  
external circuits. Because trends indicate a growing demand for standby power, it is  
recommended that a family of designs be created to supply 720 mA, 1.0 A, or 1.5 A to meet  
various customer requirements. Overcurrent protection is required on the +5VSB output  
regardless of the output current rating. This ensures the power supply will not be damaged  
if external circuits draw more current than the supply can provide.  
3.4.4 Power-on Time  
The power-on time is defined as the time from when PS_ON# is pulled low to when the  
+5VDC and +3.3VDC outputs are within the regulation ranges specified in Section 3.2.1.  
The power-on time shall be less than 500 ms.  
+5VSB shall have a power-on time of 2 seconds maximum after application of valid AC  
voltages.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
3.4.5 Risetime  
The output voltages shall rise from <10% of nominal to within the regulation ranges  
specified in Section 3.2.1 within 0.1 ms to 20 ms (0.1 ms T2 20 ms).  
3.4.6 Overshoot at Turn-on/Turn-off  
The output voltage overshoot upon the application or removal of the input voltage, or the  
assertion/deassertion of PS_ON#, under the conditions specified in Section 3.1, shall be  
less than 10% above the nominal voltage. There must be a smooth and continuous ramp of  
each DC output voltage from 10% to 90% of its final set point within the regulation band,  
while loaded as specified in Section 3.3. The smooth turn-on requires that during the 10%  
to 90% portion of the rise time, the slope of the turn-on waveform must be positive and  
have a value of between 0 V/ms and [Vout,nominal] V / 0.1 ms. Also, for any 5 ms  
segment of the 10% to 90% rise-time waveform, a straight line drawn between the end  
points of the waveform segment must have a slope [Vout,nominal] V / 20 ms. No  
voltage of opposite polarity shall be present on any output during turn-on or turn-off.  
3.4.7 Reset after Shutdown  
If the power supply latches into a shutdown state due to fault condition on its outputs, the  
power supply shall return to normal operation only after the fault has been removed and the  
PS_ON# (or AC input) has been cycled OFF/ON with a minimum OFF time of 1 second.  
3.4.8 +5VSB at AC Power Down  
After AC power is removed, the +5VSB standby voltage output should remain at its steady  
state value for the minimum holdup time specified in Section 3.3.8 until it begins to  
decrease in voltage. The decrease shall be monotonic in nature, dropping to 0.0 V. There  
shall be no other perturbations of this voltage at or following removal of AC power.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
3.5 Output Protection  
3.5.1 Overvoltage Protection  
The overvoltage sense circuitry and reference shall reside in packages that are separate and  
distinct from the regulator control circuitry and reference. No single point fault shall be  
able to cause a sustained overvoltage condition on any or all outputs. The supply shall  
provide latch-mode overvoltage protection as defined below.  
Table 11: Overvoltage Protection  
Output  
Min.  
Nom.  
Max.  
Unit  
+12VDC  
+5VDC  
-
-
15.6  
7.0  
Volts  
Volts  
Volts  
5.74  
3.76  
6.3  
4.2  
+3.3VDC  
4.3  
3.5.2 Short Circuit Protection  
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 +3.3VDC, +5VDC, or +12VDC  
rails to return or any other rail. Shorts between main output rails and +5VSB shall not  
cause any damage to the power supply. The power supply shall either shut down and latch  
off or fold back for shorting the negative rails. The +5VSB must be capable of being  
shorted indefinitely, but when the short is removed, the power supply shall recover  
automatically or by cycling the PS_ON#. The power supply shall be capable of  
withstanding a continuous short-circuit to the output without damage or overstress to the  
unit (components, PCB traces, connectors, etc.) under the input conditions specified in  
Section 3.1. The maximum short-circuit energy in any output shall not exceed 240 VA.  
3.5.3 No Load Operation  
No damage or hazardous condition should occur with all the DC output connectors  
disconnected from the load. The power supply may latch into the shutdown state.  
3.5.4 Overcurrent Protection  
Overload currents applied to each tested output rail will cause the output to trip before  
reaching or exceeding 240 VA. For testing purposes, the overload currents should be  
ramped at a minimum rate of 10 A/s starting from full load.  
3.5.5 Output Bypass  
The output return may be connected to the power supply chassis. The return will be  
connected to the system chassis by the system components.  
Page 19  
 
Intel ATX Power Supply Design Guide  
Version 0.9  
4. Mechanical Requirements  
4.1 Labeling / Marking  
Each supply shall be marked with the following, at minimum:  
Access warning text (“Do not remove this cover. Trained service personnel only. No  
user serviceable components inside.”) in English, German, Spanish, French, Chinese,  
and Japanese with universal warning markings.  
Manufacturer information: manufacturer's name, part number, and lot date code in  
human-readable text format, etc.  
Nominal AC input operating voltages (100-127 VAC and 200-240 VAC) and current  
rating certified by all agencies specified in Section 8.  
DC output voltages and current ratings.  
4.2 Physical Dimensions  
The supply shall be enclosed and meet the physical outline shown in either Figure 2 or 3, as  
applicable.  
Page 20  
 
Intel ATX Power Supply Design Guide  
Version 0.9  
53 REF  
Air inlet grill, 55% open area.  
WIRE HARNESS  
16 REF  
150 REF  
20.0  
(2X)  
4.0X6  
(2X)  
Optional air  
inlet area.  
Optional air  
inlet area.  
146.0  
140 REF  
86 REF  
138.0  
No. 6-32 UNC-2B THREADED HOLE (4X)  
See Note 4.  
Notes; unless otherwise  
specified:  
1. Dimensions are in mm.  
2.  
Drawing is not to scale.  
64.0  
74.0  
3. Tolerances:  
X +/- 1  
X.X +/- 0.5  
4. If a wire grill is required  
for acoustics or thermals,  
the grill and screws must  
be flush mounted.  
114.0  
6.0  
16.0  
6.0 (2X)  
Figure 2: Power Supply Dimensions for Chassis in Which the P/S Does Not Cool  
Processor  
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Intel ATX Power Supply Design Guide  
Version 0.9  
53 REF  
WIRE HARNESS  
11.0 x 5.0 cutouts (4X);  
min 6.0 clearance under  
16 REF  
cutout from inside top cover.  
150 REF  
4.0X6  
20.0  
(2X)  
See Note 5.  
94.0  
5.0  
Area on top surface  
inside dotted lines should  
have 60% minimum open  
area for proper venting.  
Eight rectangular holes  
are for air duct mounting  
to direct airflow across  
processor heatsink.  
146.0  
80.0  
140 REF  
5.0  
45.0  
114.0  
138.0  
8.0  
No. 6-32 UNC-2B THREADED HOLE (4X)  
86 REF  
9.0 x 3.2 cutouts (4X);  
min 5.0 clearance under  
cutout from inside top cover.  
Notes; unless otherwise specified:  
1. Dimensions are in mm.  
See Note 4.  
2.  
Drawing is not to scale.  
3. Tolerances:  
X +/- 1  
X.X +/- 0.5  
4. If a wire grill is required  
for acoustics or thermals,  
the grill and screws must  
be flush mounted.  
5. Bottom side (not pictured)  
may be user-accessible in  
final system installation.  
Cover openings as  
64.0  
74.0  
6.0  
114.0  
16.0  
necessary to prevent  
access to non-SELV  
circuitry and to meet product  
safety requirements.  
6.0 (2X)  
Figure 3: Power Supply Dimensions for Chassis in Which the P/S Cools the Processor  
Page 22  
 
Intel ATX Power Supply Design Guide  
Version 0.9  
4.3 Airflow / Fan  
In general, exhausting warm air from the chassis enclosure via a power supply fan at the  
rear panel is the preferred system-level airflow solution. Other solutions may be  
implemented, however, and some system/chassis designers may reverse this airflow to meet  
specific system cooling requirements. Ultimately, the choice of fan location and direction  
for a power supply in an ATX system must yield acceptable cooling for the power supply  
and all integrated chassis components.  
It is suggested that an 80 mm ball bearing fan be used in conjunction with a thermally  
sensitive fan speed control circuit to balance system-level thermal and acoustic  
performance. The thermal fan speed control typically should sense the temperature of the  
secondary heatsink and/or incoming ambient air and adjust the fan speed as necessary to  
keep power supply and system component temperatures within specification. Both the  
power supply and system designer should be aware of the dependencies of the system and  
power supply temperatures on the control circuit response curve and fan size and specify  
them accordingly.  
The intake and exhaust grills of the power supply should remain suitably free of obstruction  
so as not to hinder airflow or generate excessive acoustic noise (i.e. no objects within 0.5  
inches of the intake or exhaust areas). The opening must be sufficiently protected to meet  
the safety requirements described in Section 8. For the grill pattern area relevant to a given  
chassis design, see Figures 2 and 3. A flush mount wire fan grill can be used instead of a  
stamped metal grill to maximize airflow and minimize acoustic noise.  
4.4 AC Connector  
The AC input receptacle should be an IEC 320 type or equivalent. In lieu of an additional  
switch, the IEC 320 receptacle may be considered the mains disconnect.  
4.5 DC Connectors  
Figure 4 shows pinouts and profiles for typical ATX power supply DC harness connectors.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
+3.3VDC  
-12VDC  
COM  
+3.3VDC  
Pin 11  
Pin 1  
Pin 1  
Pin 6  
COM  
Pin 1  
Pin 4  
+12VDC  
COM  
COM  
+3.3VDC  
COM  
COM  
+3.3VDC  
+3.3VDC  
COM  
PS_ON#  
COM  
+5VDC  
COM  
+5VDC  
+5VDC  
Peripheral Power  
Connector  
Aux Power Connector  
+5VDC  
COM  
(250 W & 300 W Systems)  
COM  
COM  
Pin 1  
Pin 4  
+5VDC  
COM  
-5VDC  
+5VDC  
+5VDC  
PWR_OK  
+5VSB  
COM  
+12VDC  
+12VDC  
Floppy Drive  
Power Connector  
ATX Main Power Connector  
Figure 4: ATX Power Supply Connectors  
(Pin-side view, not to scale)  
Listed or recognized component appliance wiring material (AVLV2), CN, rated min 85 °C,  
300 VDC shall be used for all output wiring. There are no specific requirements for length  
or color of wiring from the power supply. The following sections suggest wire color  
coding that is followed by many vendors, but this color coding is NOT required.  
4.5.1 ATX Main Power Connector  
Connector: MOLEX 39-01-2200 or equivalent  
(Mating motherboard connector is Molex 39-29-9202 or equivalent)  
18 AWG is suggested for all wires except for the +3.3 V supply and sense return wires  
combined into pin 11 (22 AWG).  
For 300 W configurations, 16 AWG is recommended for all +5VDC, +3.3VDC, and COM.  
Pin  
Signal  
Color  
Pin  
11  
Signal  
Color  
1
+3.3VDC  
Orange  
+3.3VDC  
Orange  
[11]  
[+3.3 V default [Brown]  
sense]  
2
+3.3VDC  
COM  
Orange  
Black  
Red  
12  
13  
14  
15  
16  
17  
18  
19  
20  
-12VDC  
COM  
Blue  
3
Black  
Green  
Black  
Black  
Black  
White  
Red  
4
+5VDC  
COM  
PS_ON#  
COM  
5
Black  
Red  
6
+5VDC  
COM  
COM  
7
Black  
Gray  
COM  
8
PWR_OK  
+5VSB  
+12VDC  
-5VDC  
+5VDC  
+5VDC  
9
Purple  
Yellow  
10  
Red  
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Intel ATX Power Supply Design Guide  
Version 0.9  
4.5.2 Auxiliary Power Connector  
(for 250 W and 300 W Configurations)  
Connector: Molex 90331-0010 (keyed  
pin 6) or equivalent  
Pin  
1
Signal  
COM  
16 AWG Wire  
Black  
2
COM  
Black  
3
COM  
Black  
4
+3.3VDC  
+3.3VDC  
+5VDC  
Orange  
Orange  
Red  
5
6
4.5.3 Peripheral Connector(s)  
Connector: AMP 1-480424-0 or MOLEX  
8981-04P or equivalent.  
Contacts: AMP 61314-1 or equivalent.  
Pin  
1
Signal  
+12VDC  
COM  
18 AWG Wire  
Yellow  
Black  
2
3
COM  
Black  
4
+5VDC  
Red  
4.5.4 Floppy Drive Connector  
Connector: AMP 171822-4 or equivalent  
Pin  
1
Signal  
+5VDC  
COM  
20 AWG Wire  
Red  
2
Black  
3
COM  
Black  
4
+12VDC  
Yellow  
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Intel ATX Power Supply Design Guide  
Version 0.9  
5. Environmental Requirements  
5.1 Temperature  
Operating ambient  
+10 °C min  
+50 °C max  
(At full load, with a maximum rate of change of 5 °C/10  
minutes, but no more than 10 °C/hr.)  
Nonoperating ambient  
-40 °C to +70 °C  
(Maximum rate of change of 20 °C/hr.)  
5.2 Thermal Shock (Shipping)  
Nonoperating  
-40 °C to +70 °C; 15 °C/min dT/dt 30 °C/min; 50 cycles;  
Duration of exposure to temperature extremes for each half  
cycle shall be 30 minutes.  
5.3 Humidity  
Operating  
To 85% relative humidity (noncondensing)  
Nonoperating  
To 95% relative humidity (noncondensing)  
Note: 95% RH is achieved with a dry bulb temperature of  
55 °C and a wet bulb temperature of 54 °C.  
5.4 Altitude  
Operating  
To 10,000 ft  
To 50,000 ft  
Nonoperating  
5.5 Mechanical Shock  
Nonoperating  
50 g, trapezoidal input; velocity change 170 in/s.  
Three drops on each of six faces are applied to each sample.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
5.6 Random Vibration  
Nonoperating  
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.  
5.7 Acoustics  
Acoustic requirements will be set by the final computer OEM system-level requirements.  
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Intel ATX Power Supply Design Guide  
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6. Electromagnetic Compatibility  
6.1 EMI  
The power supply shall comply with CISPR 22, Class B, for both conducted and radiated  
emissions with a 4 dB margin. Tests shall be conducted using a shielded DC output cable  
to a shielded load. The load shall be adjusted as follows for three tests: No load on each  
output; 50% load on each output; and 100% load on each output. Tests will be performed  
at 100 VAC 50 Hz, 120 VAC 60 Hz, and 220 VAC 50 Hz power.  
6.2 Input Line Current Harmonic Content (Optional)  
If applicable to sales in Japan or Europe, the power supply shall meet the requirements of  
EN61000-3-2 Class D and the Guidelines for the Suppression of Harmonics in Appliances  
and General Use Equipment Class D for harmonic line current content at full rated power.  
6.3 Magnetic Leakage Fields  
A PFC choke magnetic leakage field shall not cause any interference with a high-resolution  
computer monitor placed next to or on top of the end use chassis. Final acceptable leakage  
field strength will be determined by the end system vendor during system level testing in  
the end use chassis.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
7. Reliability  
7.1 Component Derating  
The following component derating guidelines shall be followed:  
Semiconductor junction temperatures shall not exceed 110 °C with an ambient of  
50 °C. Any exceptions are subject to final approval.  
Inductor case temperature shall not exceed safety agency requirements.  
Capacitor case temperature shall not exceed 95% of rated temperature.  
Resistor wattage derating shall be > 30%.  
Component voltage and current derating shall be > 10% at 50 °C. Any exceptions are  
subject to final approval.  
Magnetic saturation of any transformer will not be allowed under any line, load, startup,  
or transient condition including 100% transients on the five main outputs or +5VSB.  
7.2 Mean Time Between Failures (MTBF)  
The MTBF of the power supply shall be calculated utilizing the Part-Stress Analysis  
method of MIL-HDBK-217F using the quality factors listed in MIL-HDBK-217F. The  
calculated MTBF of the power supply shall be greater than 100,000 hours under the  
following conditions:  
Full rated load  
120 VAC input  
Ground benign  
25 °C ambient.  
The calculated MTBF of the power supply shall be greater than 30,000 hours under the  
following conditions:  
Full rated load  
120 VAC input  
Ground benign  
50 °C ambient.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
8. Safety Requirements  
8.1 North America  
The power supply must be certified by UL or CSA for use in the USA and Canada under  
the following conditions:  
The supply must be Recognized for use in Information Technology Equipment  
including Electrical Business Equipment per UL 1950, 3rd edition, without D3  
deviations and CAN/CSA C22.2 no. 950-95. The certification must include external  
enclosure testing for the AC receptacle side of the power supply (see Figures 2 and 3).  
The supply must have a full complement of tests conducted as part of the certification,  
such as input current, leakage current, hipot, temperature, energy discharge test,  
transformer output characterization test (open circuit voltage, short circuit current and  
maximum VA output), and abnormal testing (to include stalled fan tests and voltage  
select switch mismatch).  
The enclosure must meet fire enclosure mechanical test requirements per clauses 2.9.1  
and 4.2 of UL 1950, 3rd edition.  
The supplier must supply the complete certification report including a test record.  
Production hipot testing must be included as a part of the certification and indicated as such  
in the certification report.  
There must not be unusual or difficult conditions of acceptability such as mandatory  
additional cooling or power derating. The insulation system shall not have temperatures  
exceeding their rating when tested in the end product.  
The certification mark shall be marked on each power supply.  
A list of the minimum temperature ratings of all AC mains connected components and the  
printed wiring board(s) shall be provided. The power supply must be evaluated for  
operator-accessible secondary outputs (reinforced insulation) that meet the requirements for  
SELV and do not exceed 240 VA under any condition of loading.  
The proper polarity between the AC input receptacle and any printed wiring boards  
connections must be maintained (i.e., brown=line, blue=neutral, green=earth/chassis).  
Failure of any single component in the fan speed control circuit shall not cause the internal  
component temperatures to exceed the abnormal fault condition temperatures per IEC 950.  
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Intel ATX Power Supply Design Guide  
Version 0.9  
8.2 International  
The vendor must provide a complete CB certificate and test report to IEC 950, 2nd edition +  
A1, A2, A3, and A4. The CB report must include ALL CB member country national  
deviations. CB report must include evaluation to EN60 950, + A1, A2, A3, A4 and  
EMKO-TSE (74-SEC) 207/94.  
All evaluations and certifications must be for reinforced insulation between primary and  
secondary circuits.  
It is highly recommended that the CB report be issued by NEMKO.  
8.3 Proscribed Materials  
Cadmium should not be used in painting or plating.  
No quaternary salt electrolytic capacitors shall be used.  
Page 31  
 

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