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SFX12V
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Enhance SFX12V Version 3.0 Power Supply Design Guide

SFX12V Power Supply Design Guide

Version 3.0
SFX12V Power Supply Design Guide Version 3.0
IMPORTANT INFORMATION AND DISCLAIMERS
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Intel and Pentium are registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries.
Copyright
* Other names and brands may be claimed as the property of others
2004 Intel Corporation.
SFX12V Power Supply Design Guide

Revision History

Version Release Date Notes
1.0 Dec, 1997 Public release
1.1 Apr, 1998
2.0 May, 2001 • Added SFX12V description
2.1 Aug, 2001 • Section 4.4 Updated Figure 4 SFX/SFX12V Connectors
• Updated all mechanical outlines to clean up
dimensioning of mounting holes.
• Added chassis cutouts for all mechanical outlines to
clarify keep-out areas.
• Added Appendix C.
• Additional power ratings added
• Updated industry standards
• Increased standby current
• Section 5.8 removed vendor name
2.2 Dec, 2001 • Section 3.23 Typical Power Distribution. Change minimum loading on 5V rail to 0.3A
• Section 3.3.2 PS_ON#. Add text “The power supply should not latch into a shutdown state when PS_ON# is driven active by pulses between 10ms to 100ms during the decay of the power rails.”
2.3 April, 2003 • Reformat and update revision table
• Update Disclaimers
• Remove guidelines for SFX without 12V connector
• Updated power and current guidance
• Added efficiency targets for light and typical loading
• Increased minimum Efficiency at full load from 68% to 70%
• Updated guidance for standby efficiency
• Added Serial ATA connector
• Updated cross regulation graphs
3.0 February, 2004 • Updated power and current guidance
• Updated cross regulation graphs
• Updated load tables
• Updated required efficiency targets. Added recommended
efficiency targets.
• Increased required minimum efficiency at typical and light load.
• Required Serial ATA connector
• Added Terminology section
• Main Power Connector changes to 2x12.
• Separate current limit on 2x2 connector for 12V2 rail
SFX12V Power Supply Design Guide Version 3.0

Contents

1. Introduction ....................................................................................................................................7
1.1. Scope .....................................................................................................................................7
1.2. Changes for Version 3.0........................................................................................................7
1.2.1. Efficiency ...................................................................................................................7
1.2.2. Increased Power........................................................................................................7
1.2.3. Main Power Connector Change.................................................................................8
1.2.4. Separate Current Limit for 12V2 on the 2x2 Connector ............................................8
1.2.5. External Fan Control - Optional .................................................................................8
1.3. Terminology............................................................................................................................8
2. Applicable Documents ..................................................................................................................9
3. Electrical .........................................................................................................................................10
3.1. AC Input..................................................................................................................................10
3.1.1. Input Over-Current Protection....................................................................................10
3.1.2. Inrush Current Limiting ..............................................................................................10
3.1.3. Input Under Voltage...................................................................................................11
3.1.4. Regulatory..................................................................................................................11
3.1.5. Catastrophic Failure Protection .................................................................................12
3.2. DC Output...............................................................................................................................12
3.2.1. DC Voltage Regulation ..............................................................................................12
3.2.2. Remote Sensing ........................................................................................................12
3.2.3. Typical Power Distribution .........................................................................................13
3.2.4. Power Limit / Hazardous Energy Levels....................................................................19
3.2.5. Efficiency ...................................................................................................................19
3.2.6. Output Ripple/Noise...................................................................................................22
3.2.7. Output Transient Response.......................................................................................24
3.2.8. Capacitive Load .........................................................................................................24
3.2.9. Closed-loop Stability ..................................................................................................25
3.2.10. +5 VDC / +3.3 VDC Power Sequencing ..................................................................25
3.2.11. Voltage Hold-up Time ..............................................................................................25
3.3. Timing / Housekeeping / Control ............................................................................................25
3.3.1. PWR_OK ...................................................................................................................26
3.3.2. PS_ON#.....................................................................................................................26
3.3.3. +5 VSB.......................................................................................................................27
3.3.4. Power-on Time ..........................................................................................................28
3.3.5. Rise Time ..................................................................................................................28
3.3.6. Overshoot at Turn-on / Turn-off.................................................................................28
3.3.7. Reset after Shutdown ................................................................................................28
3.3.8. +5 VSB at AC Power-down........................................................................................28
3.4. Output Protection....................................................................................................................29
3.4.1. Over Voltage Protection.............................................................................................29
SFX12V Power Supply Design Guide
3.4.2. Short-circuit Protection ..............................................................................................29
3.4.3. No-load Operation .....................................................................................................29
3.4.4. Over Current Protection.............................................................................................29
3.4.5. Over-Temperature Protection....................................................................................30
3.4.6. Output Bypass ...........................................................................................................30
4. Mechanical......................................................................................................................................31
4.1. Labeling / Marking ..................................................................................................................31
4.2. Airflow / Fan............................................................................................................................32
4.3. AC Connector .........................................................................................................................33
4.4. DC Connectors .......................................................................................................................33
4.4.1. SFX Main Power Connector ......................................................................................35
4.4.2. Peripheral Connector(s).............................................................................................36
4.4.3. Floppy Drive Connector .............................................................................................36
4.4.4. +12 V2 Power Connector...........................................................................................36
4.4.5. Serial ATA Power Connector.....................................................................................37
5. Environmental ................................................................................................................................38
5.1. Temperature ...........................................................................................................................38
5.2. Thermal Shock (Shipping)......................................................................................................38
5.3. Humidity..................................................................................................................................38
5.4. Altitude....................................................................................................................................38
5.5. Mechanical Shock ..................................................................................................................38
5.6. Random Vibration...................................................................................................................39
5.7. Acoustics ................................................................................................................................39
5.8. Ecological Requirements .......................................................................................................39
6. Electromagnetic Compatibility .....................................................................................................40
6.1. Emissions ...............................................................................................................................40
6.2. Immunity ...................................................................................................................................40
6.3. Input Line Current Harmonic Content.....................................................................................40
6.4. Magnetic Leakage Fields........................................................................................................41
6.5. Reliability ................................................................................................................................41
6.6. Voltage Fluctuations and Flicker ...........................................................................................41
7. Safety ..............................................................................................................................................42
7.1. North America ........................................................................................................................42
7.2. International............................................................................................................................43
8. SYSTEM COOLING CONSIDERATIONS.......................................................................................44
APPENDIX A GUIDELINES FOR A LOWER PROFILE PACKAGE ...................................................45
APPENDIX B GUIDELINES FOR A TOP MOUNT FAN PACKAGE ...................................................48
APPENDIX C GUIDELINES FOR A REDUCED DEPTH, TOP MOUNT FAN PACKAGE ..................51
APPENDIX D GUIDELINES FOR A LOWER PROFILE PACKAGE ...................................................54
APPENDIX E GUIDELINES FOR PS3 FORM FACTOR .....................................................................57
SFX12V Power Supply Design Guide Version 3.0
Figures
Figure 1 Cross Loading Graph for 160W Configuration ........................................................................13
Figure 2 Cross Loading Graph for 180W Configuration ........................................................................14
Figure 3 Cross Loading Graph for 220W Configuration ........................................................................15
Figure 4 Cross Loading Graph for 240W Configuration ........................................................................16
Figure 5 Cross Loading Graph for 270W Configuration ........................................................................17
Figure 6 Cross Loading Graph for 300W Configuration ........................................................................18
Figure 7 Differential Noise Test Setup ..................................................................................................23
Figure 8 Power Supply Timing ..............................................................................................................25
Figure 9 PS_ON# Signal Characteristics ..............................................................................................27
Figure 10 SFX12V Connectors (Pin-side view, not to scale) ................................................................34
Figure 11 Serial ATA connector .............................................................................................................37
Figure 12 40 mm Profile Mechanical Outline........................................................................................46
Figure 13 Chassis Cutout .....................................................................................................................47
Figure 14 Top Mount Fan Profile Mechanical Outline...........................................................................49
Figure 15 Chassis Cutout .....................................................................................................................50
Figure 16 Recessed Fan Mounting.......................................................................................................50
Figure 17 Reduced Depth Top Mount Fan Profile Mechanical Outline.................................................52
Figure 18 Chassis Cutout .....................................................................................................................53
Figure 19 60 mm Mechanical Outline ...................................................................................................55
Figure 20 Chassis Cutout .....................................................................................................................56
Figure 21 PS3 Mechanical Outline........................................................................................................58
Tables
Table 1: AC Input Line Requirements ....................................................................................................10
Table 2: DC Output Voltage Regulation.................................................................................................12
Table 3: Typical Power Distribution for a 160 W SFX12V Configurations .............................................13
Table 4: Typical Power Distribution for 180 W SFX12V Configurations ................................................14
Table 5: Typical Power Distribution for 220 W SFX12V Configurations ................................................15
Table 6: Typical Power Distribution for 240 W SFX12V Configurations ................................................16
Table 7: Typical Power Distribution for 270 W SFX12V Configurations ................................................17
Table 8: Typical Power Distribution for 300 W SFX12V Configurations ................................................18
Table 9: Efficiency Vs Load ..................................................................................................................19
Table 10. Loading Table for Efficiency Measurements.........................................................................20
Table 11: Energy Star Input Power Consumption.................................................................................21
Table 12: DC Output Noise/Ripple........................................................................................................23
Table 13: DC Output Transient Step Sizes ...........................................................................................24
Table 14: Output Capacitive Loads.......................................................................................................24
Table 15: PWR_OK Signal Characteristics ..........................................................................................26
Table 16: PS_ON# Signal Characteristics ............................................................................................27
Table 17: Over Voltage Protection ........................................................................................................29
Table 18: Harmonic Limits, Class D Equipment ...................................................................................41
6
SFX12V Power Supply Design Guide

1. Introduction

1.1. Scope

This document provides design suggestions for a family of small form factor power supplies that are primarily intended for use with microATX and FlexATX systems. The connectors conform to the basic requirements of the ATX main board specification except that -5 V is not available. It should not be inferred that all SFX power supplies must conform exactly to the content of this document. The design specifics described are not intended to support all possible systems, because power supply needs vary depending on system configuration.

1.2. Changes for Version 3.0

This section provides a brief summary of the changes to the SFX Power Supply Design Guide for Version 3.0

1.2.1. Efficiency

Minimum measured efficiency is required to be 70% at full, typical (~50%) load and 60% at light (~20%) load. New recommended guidance has been added to provide direction for expected future requirements.

1.2.2. Increased Power

The trend for faster and more powerful systems results in an increasing need for higher rated power supplies. Additional power ratings have been added with increased 12 VDC current to meet the needs of present and future system needs. Wattages up to 300 W have been defined to meet the requirements of today’s and the next generation of high performance
®
Intel Pentium not intended to limit the choice of power ratings available. Loading table have been included to provide guidance for the loading on each voltage rail which can be used to determine if the minimum efficiency meet the recommendations. Included with the power recommendations are updated cross regulation graphs that show typical system power loading of 5V +3.3V rail vs. the 12V rail.
4 processor-based systems. These recommendations are for guidance and are
SFX12V Power Supply Design Guide Version 3.0

1.2.3. Main Power Connector Change

The main power connect has changed to a 2 x 12 connector from a 2 x 10 connector. This was changed to support 75 watt PCI Express* requirements.

1.2.4. Separate Current Limit for 12V2 on the 2x2 Connector

The 12V rail on the 2 x 2 power connector should be a separate current limited output to meet the requirements of UL and EN 60950.

1.2.5. External Fan Control - Optional

With the implementation of Suspend To RAM (STR or S3 sleep state), the system can obtain a low power condition without the need for external fan shutoff. In STR mode, the main outputs including 12 V are not available from the power supply and all system fans and the power supply fan will be off. FANC and FANM functions described in Version 1.1 have been removed for Version 2.0. Some vendors may still offer the external Fan functions as an option.

1.3. Terminology

The following terms are used in this document:
Term Description
Required
Recommended
Optional
B
A
CFM
Monotonically
The status given to items within this design guide, which are required to meet design guide and a large majority of system applications.
The status given to items within this design guide, which are not required to meet design guide, however, are required by many system applications.
The status given to items within this design guide, which are not required to meet design guide, however, some system applications may optionally use these features.
Declared sound power, LwAd. The declared sound power level shall be measured according to ISO* 7779 for the power supply and reported according to ISO 9296.
Cubic Feet per Minute (airflow).
A waveform changes from one level to another in a steady fashion, without intermediate retracement or oscillation.
Noise
The periodic or random signals over frequency band of 0 Hz to 20 MHz.
8
SFX12V Power Supply Design Guide

2. Applicable Documents

The latest revision in effect of the following documents forms a part of this document to the extent specified.
Document title Description
FCC Rules Part 15, Class B Title 47, Code of Federal Regulations, Part 15
ICES-003: 1997, Class B Interference-Causing Equipment Standard – Digital Apparatus
EN 55022: 1998 + Amendment A1:2000 Class B
CISPR 22: 1997, Class B
AS/NZS 3548:1995, Class B
EN 55024:1998
IEC 60950, 3rd ed., 1999 Safety of Information Technology Equipment
Information Technology Equipment – Radio disturbance characteristics – Limits and methods of measurement
Information Technology Equipment – Radio disturbance characteristics – Limits and methods of measurement
Information Technology Equipment – Radio disturbance characteristics – Limits and methods of measurement
Information Technology Equipment – Immunity Characteristics – Limits and methods of measurement
EN 60950: 2000 Safety of Information Technology Equipment
UL 60950, 3rd ed., 2000 Safety of Information Technology Equipment
CSA 22.2 No. 60950-00 Safety of Information Technology Equipment
SFX12V Power Supply Design Guide Version 3.0

3. Electrical

The electrical requirements that follow are to be met over the environmental ranges specified in Section 5 unless otherwise noted.

3.1. AC Input

Table 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 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 power supply must be able to start up under peak loading at 90 VAC
Table 1: AC Input Line Requirements
Parameter Minimum Nominal* Maximum Unit
Vin (115 VAC) 90 115 135 VAC
Vin (230 VAC) 180 230 265 VAC
Vin Frequency 47 -- 63 Hz
*Note: Nominal voltages for test purposes are considered to be within ±1.0 V of nominal.

3.1.1. Input Over-Current Protection

The power supply shall incorporate primary fusing for input over-current protection to prevent damage to the power supply and meet product safety requirements. Fuses should be
1
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.
rms
rms
1
. For Denmark and Switzerland international safety requirements, if the internal over-current protective devices exceed 8A for Denmark and 10A for Switzerland, then the power supply must pass international safety testing to EN 60950 using a maximum 16A over-current protected branch circuit, and this 16A (time delay fuse) branch circuit protector must not open during power supply abnormal operation (output short circuit and component fault) testing.
10
SFX12V Power Supply Design Guide

3.1.3. Input Under Voltage

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.

3.1.4. Regulatory

The power supply is required to be tested and comply with the most current version of the following regulatory specification requirements and/or standards
1.1.1.1 PRODUCT SAFETY
UL* 60950, 3
EN*60 950, 3
IEC*60 950, 3rd Edition (CB Report to include all national deviations)
EU* Low Voltage Directive (73/23/EEC) (CE Compliance)
rd
Edition –CAN/CSA-C22.2-60950-00,
rd
Edition
GB4943-90 CCIB* (China)
1.1.1.2 ELECTROMAGNETIC CAMPATIBILITY
FCC*, Class B, Part 15 (Radiated & Conducted Emissions)
CISPR* 22 / EN55022, 3rd Edition (Radiated & Conducted Emissions)
EN55024 (ITE Specific Immunity)
EN 61000-4-2 – Electrostatic Discharge
EN 61000-4-3– Radiated RFI Immunity
EN 61000-4-4– Electrical Fast Transients.
EN 61000-4-5 – Electrical Surge
EN 61000-4-6 – RF Conducted
EN 61000-4-8 – Power Frequency Magnetic Fields
EN 61000-4-11 – Voltage Dips, Short Interrupts and Fluctuations
EN61000-3-2 (Harmonics)
EN61000-3-3 (Voltage Flicker)
EU EMC Directive ((8/9/336/EEC) (CE Compliance)
1.1.1.3 Other Certifications and/or Declarations
GB925 (China/CCC*), CNS13438 (Taiwan/BSMI*)
AS/NZ3548 (Australia/C-tick* based on CISPR22)
SFX12V Power Supply Design Guide Version 3.0

3.1.5. Catastrophic Failure Protection

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
• Emission of molten material
• Earth ground fault (short circuit to ground or chassis enclosure)

3.2. DC Output

3.2.1. DC Voltage Regulation

The DC output voltages shall remain within the regulation ranges shown in Table 2 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 at any steady state temperature and operating conditions specified in Section 5. DC Output Voltage Regulation
Table 2: DC Output Voltage Regulation
Output Range Minimum Nominal Maximum Unit
+12V1DC ±5% +11.40 +12.00 +12.60 Volts
+12 V2DC (Note) ±5% +11.40 +12.00 +12.60 Volts
+5 VDC ±5% +4.75 +5.00 +5.25 Volts
+3.3 VDC ±5% +3.14 +3.30 +3.47 Volts
-12 VDC ±10% -10.80 -12.00 -13.20 Volts
+5 VSB ±5% +4.75 +5.00 +5.25 Volts
Note: At +12 VDC peak loading, regulation at the +12 VDC output can go to ± 10%.

3.2.2. Remote Sensing

The +3.3 VDC output should have provisions for remote sensing to compensate for excessive cable drops. The default sense should be connected to pin 11 of the 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.
12
SFX12V Power Supply Design Guide

3.2.3. Typical Power Distribution

DC output power requirements and distributions will vary based on specific system options and implementation. Significant dependencies include the quantity and types of processors, memory, add-in card slots, and peripheral bays, as well as support for advanced graphics or other features. Tables 3 through xx show the power distribution for power supplies in the range of 160 W to 300 W. Figure 2 through Figure 4 graphically shown the recommendations for cross regulation. It is ultimately the responsibility of the designer to define a power budget for a given target product and market.
Table 3: Typical Power Distribution for a 160 W SFX12V Configurations
Minimum
Current
Output
+12 VDC 1.0 9.0 10.0
+5 VDC 0.3 12.0 (Note)
+3.3 VDC 0.5 16.7 (Note)
-12 VDC 0.0 0.3
+5 VSB 0.0 1.5 2.0
Note: Total combined output of 3.3 V and 5 V is
Peak currents may last up to 17 seconds with not more than one occurrence per minute
(amps)
70
60
50
40
30
20
10
5V + 3.3V power (watts)
0
0 50 100 150
Maximum
Current
(amps)
:
160W Cross Regulation
(5V rail + 3.3V rail vs. 12V)
12V power (watts)
Peak Current
(amps)
Combined Power (5V rail + 3.3V rail)
Figure 1 Cross Loading Graph for 160W Configuration
SFX12V Power Supply Design Guide
p
(
)
Table 4: Typical Power Distribution for 180 W SFX12V Configurations
Peak
Current
(amps)
Output Minimum
Current
(amps)
+12 VDC 1.0 13.0 15.0
+5 VDC 0.3 12.0 (Note)
+3.3 VDC 0.5 16.7 (Note)
-12 VDC 0.0 0.3
+5 VSB 0.0 2.0 2.5
Note: Total combined output of 3.3 V and 5 V is
Peak currents may last up to 17 seconds with not more than one occurrence per minute
Maximum
Current
(amps)
:
180W Cross Regulation
(5V rail + 3.3V rail vs. 12V)
70
60
watts
50
40
ower
30
Combined Power (5V rail + 3.3V rail)
20
10
5V + 3.3V
0
0 50 100 150 200
12V power (w atts)
Figure 2 Cross Loading Graph for 180W Configuration
14
SFX12V Power Supply Design Guide
Table 5: Typical Power Distribution for 220 W SFX12V Configurations
Peak Current (amps)
Minimum Current
Output
+12 VDC 1.0 15.0 17.0
+5 VDC 0.3 13.0 (Note)
+3.3 VDC 0.5 17.0 (Note)
-12 VDC 0.0 0.3
+5 VSB 0.0 2.0 2.5
Note: Total combined output of 3.3 V and 5 V is
Peak currents may last up to 17 seconds with not more than one occurrence per minute
(amps)
Maximum Current (amps)
:
220W Cross Regulat ion
(5V rail + 3.3V rai l vs. 12V)
90
80 70
60
50 40
Combined Power (5V rail + 3.3V rail)
30
20 10
5V + 3.3V power (watts)
0
0 50 100 150 200
12V power (watts)
Figure 3 Cross Loading Graph for 220W Configuration
SFX12V Power Supply Design Guide Version 3.0
Table 6: Typical Power Distribution for 240 W SFX12V Configurations
Peak
Current
(amps)
Output Minimum
Current
(amps)
+12 VDC 1.0 16.0 18.0
+5 VDC 0.3 18.0 (Note)
+3.3 VDC 0.5 17.0 (Note)
-12 VDC 0.0 0.3
+5 VSB 0.0 2.0 2.5
Note: Total combined output of 3.3 V and 5 V is
Peak currents may last up to 17 seconds with not more than one occurrence per minute
Maximum
Current
(amps)
:
240W Cross Regulation
(5V rail + 3.3V rail vs. 12V)
120
100
80
60
Combined Power (5V rail + 3.3V rail)
40
20
5V + 3.3V power (watts)
0
0 50 100 150 200
12V power (watts)
Figure 4 Cross Loading Graph for 240W Configuration
16
SFX12V Power Supply Design Guide
p
(
)
Table 7: Typical Power Distribution for 270 W SFX12V Configurations
Output Minimum
Current
(amps)
+12 V1DC
+12 V2DC
+5 VDC
+3.3 VDC
-12 VDC
+5 VSB
Note: Total combined output of 3.3 V and 5 V is 120 W
Peak currents may last up to 17 seconds with not more than one occurrence per minute
1.0 7.0 9.0
1.0 13.0
0.3 18.0
0.5 17.0
0.0 0.3
0.0 2.0 2.5
Maximum
Current
(amps)
Peak
Current
(amps)
270W Cross Regulation
(5V rail + 3.3V rail vs. 12V1 +12V2)
120
100
watts
80
60
ower
Combined Power (5V rail + 3.3V rail)
40
20
5V + 3.3V
0
0 40 80 120 160 200 240
12V power (watts)
Figure 5 Cross Loading Graph for 270W Configuration
SFX12V Power Supply Design Guide Version 3.0
Table 8: Typical Power Distribution for 300 W SFX12V Configurations
Recommended for Appendix E (PS3)
Minimum Current
Output
+12 V1DC
+12 V2DC
+5 VDC
+3.3 VDC
-12 VDC
+5 VSB
(amps)
1.0 8.0 10.0
1.0 14.5
0.3 18.0
0.5 18.0
0.0 0.4
0.0 2.0 2.5
Maximum Current (amps)
Peak Current (amps)
Note: Total combined output of 3.3 V and 5 V is
Peak currents may last up to 17 seconds with not more than one occurrence per minute
140
120
100
80
60
40
5V + 3.3V power (watts)
20
0
0 40 80 120 160 200 240 280
:
300W Cross Regulation
(5V rail + 3.3V rail vs . 12V1 + 12V2)
12V pow er (watts)
Combined Power (5V rail + 3.3V rail)
18
Figure 6 Cross Loading Graph for 300W Configuration
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