Enhance EPS12V Version 2.0 Power Supply Design Guide
SSI
EPS12V
Power Supply Design Guide
A Server System Infrastructure (SSI) Specification
For Entry Chassis Power Supplies
Version 2.0
Revision History
Orig./Rev. Description of Changes Date
1.7 Initial release
2.0 Added higher power levels for 650W power supplies and updated 12V peak
requirements for 450W and 550W power levels.
Added PS/2 and 230mm stretch PS/2 form-factor options.
Added requirements for the higher power levels: 3rd 240VA channel, output connector,
efficiency, and output loading.
Updated requirements for PWOK.
Removed temperature rise requirements from thermal section.
9/24/2002
SSI
EPS12V Power Supply Design Guide, V2.0
Disclaimer:
THIS SPECIFICATION IS PROVIDED "AS IS" WITH NO WARRANTIES
WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY,
NONINFRINGEMENT, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY
WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR
SAMPLE. WITHOUT LIMITATION, THE PROMOTERS (Intel Corporation, Dell
Computer Corporation, Hewlett Packard Company, Silicon Graphics Inc., and
International Business Machines Corporation) DISCLAIM ALL LIABILITY FOR COST OF
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOST PROFITS, LOSS
OF USE, LOSS OF DATA OR ANY INCIDENTAL, CONSEQUENTIAL, DIRECT,
INDIRECT, OR SPECIAL AMAGES, WHETHER UNDER CONTRACT, TORT,
WARRANTY OR OTHERWISE, ARISING IN ANY WAY OUT OF USE OR RELIANCE
UPON THIS SPECIFICATION OR ANY INFORMATION HEREIN.
The Promoters disclaim all liability, including liability for infringement of any proprietary
rights, relating to use of information in this specification. No license, express or implied,
by estoppel or otherwise, to any intellectual property rights is granted herein.
This specification and the information herein is the confidential and trade secret
information of the Promoters. Use, reproduction and disclosure of this specification and
the information herein is subject to the terms of the S.S.I. Specification Adopter's
Agreement.
Copyright Intel Corporation, Dell Computer Corporation, Hewlett Packard Company, Silicon Graphics Inc., International Business
Machines Corporation, 2002.
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EPS12V Power Supply Design Guide, V2.0
Contents
1 Purpose .....................................................................................................................................5
2 Conceptual Overview..................................................................................................................5
3 Definitions/Terms/Acronyms.......................................................................................................5
4 Mechanical Overview..................................................................................................................7
4.1 Airflow Requirements.................................................................................................................8
4.2 Temperature Requirements ........................................................................................................8
5 AC Input Requirements...............................................................................................................9
5.1 AC Inlet Connector....................................................................................................................9
5.2 AC Input Voltage Specification....................................................................................................9
5.3 Input Under Voltage...................................................................................................................9
5.4 Efficiency .................................................................................................................................9
5.5 AC Line Dropout......................................................................................................................10
5.6 AC Line Fuse..........................................................................................................................10
5.7 AC Inrush...............................................................................................................................10
5.8 AC Line Transient Specification.................................................................................................11
5.9 AC Line Fast Transient Specification..........................................................................................11
6 DC Output Specification............................................................................................................12
6.1 Output Connectors ..................................................................................................................12
6.1.1 Required Baseboard power connector..................................................................................12
6.1.2 Required Processor Power Connector..................................................................................13
6.1.3 Required Peripheral Power Connectors ................................................................................14
6.1.4 Floppy Power Connector....................................................................................................15
6.1.5 Optional Server Signal Connector........................................................................................15
6.1.6 Optional Workstation Power Connector................................................................................16
6.2 Grounding..............................................................................................................................16
6.3 Remote Sense........................................................................................................................16
6.4 Output Power/Currents.............................................................................................................17
6.4.1 Standby Outputs...............................................................................................................20
6.5 Voltage Regulation..................................................................................................................20
6.6 Dynamic Loading....................................................................................................................21
6.7 Capacitive Loading..................................................................................................................22
6.8 Ripple / Noise.........................................................................................................................22
6.9 Timing Requirements...............................................................................................................22
7 Protection Circuits....................................................................................................................26
7.1 Current Limit...........................................................................................................................26
7.2 240VA Protection....................................................................................................................26
7.3 Over Voltage Protection...........................................................................................................27
7.4 Over Temperature Protection....................................................................................................27
8 Control and Indicator Functions................................................................................................28
8.1 PSON#..................................................................................................................................28
8.2 PWOK (Power OK)..................................................................................................................29
8.3 Field Replacement Unit (FRU) Signals........................................................................................29
8.3.1 FRU Data........................................................................................................................29
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8.3.2 FRU Data Format..............................................................................................................30
EPS12V Power Supply Design Guide, V2.0
9 MTBF.......................................................................................................................................32
10 Agency Requirements...............................................................................................................32
Figures
Figure 1: Enclosure Drawing...................................................................................................................7
Figure 2: Output Voltage Timing............................................................................................................23
Figure 3: Turn On/Off Timing (Single Power Supply).................................................................................25
Figure 4: PSON# Signal Characteristics .................................................................................................28
Tables
Table 1: Thermal Requirements ..............................................................................................................8
Table 2: AC Input Rating........................................................................................................................9
Table 3: Efficiency...............................................................................................................................10
Table 4: AC Line Sag Transient Performance..........................................................................................11
Table 5: AC Line Surge Transient Performance.......................................................................................11
Table 6: P1 Baseboard Power Connector – 450/550W..............................................................................12
Table 7: P1 Baseboard Power Connector – 550/650W..............................................................................13
Table 8: Processor Power Connector – 450/550W ...................................................................................13
Table 9: Processor Power Connector – 550/650W ...................................................................................14
Table 10: Peripheral Power Connectors..................................................................................................14
Table 11: P8 Floppy Power Connector...................................................................................................15
Table 12: Server Signal Connector........................................................................................................15
Table 13: Workstation Power Connector.................................................................................................16
Table 14: 650 W Load Ratings ..............................................................................................................17
Table 15: 550 W Load Ratings – Dual +12V Rails for Processor Power.......................................................18
Table 16: 550 W Load Ratings – Single +12V Rail for Processor Power......................................................19
Table 17: 450 W Load Ratings ..............................................................................................................20
Table 18: Voltage Regulation Limits.......................................................................................................21
Table 19: Optional +5V Regulation Limits...............................................................................................21
Table 20: Transient Load Requirements.................................................................................................21
Table 21: Capacitive Loading Conditions ................................................................................................22
Table 22: Ripple and Noise...................................................................................................................22
Table 23: Output Voltage Timing...........................................................................................................23
Table 24: Turn On/Off Timing................................................................................................................24
Table 25: Over Current Protection.........................................................................................................26
Table 26: Over Current Limits ...............................................................................................................27
Table 27: Over Voltage Limits...............................................................................................................27
Table 28: PSON# Signal Characteristic...................................................................................................28
Table 29: PWOK Signal Characteristics..................................................................................................29
Table 30: FRU Device Information.........................................................................................................30
Table 31: FRU Device Product Information Area......................................................................................30
Table 32: MultiRecord information Area..................................................................................................31
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EPS12V Power Supply Design Guide, V2.0
1 Purpose
This specification defines a non-redundant power supply that supports entry server computer systems.
Recommendations for 450 W, 550 W, and 650 W power supplies with 6 outputs (3.3 V, 5 V, 12V1, 12V2, 12V3, 12 V, and 5 VSB) are provided. The form factor is based on the PS/2 power supply, with three enclosure lengths
defined to support output power levels ranging from 400 to 700W. Connector/cable assemblies are required for
the motherboard power, remote sensing and control functions, and peripheral power. Because of its connector
leads, the entry-level power supply is not intended to be a hot swap type of power supply. The cooling fan should
meet the acoustical requirements for the system, while providing system cooling.
The parameters of this supply are defined in this specification for open industry use.
2 Conceptual Overview
In the Entry server market, the bulk power system must source power on several output rails.
These rails are typically as follows:
• +3.3 V
• +5 V
• +12 V
• –12 V
• +5 V standby
NOTE
Local DC-DC converters shall be utilized for processor power, and will ideally convert power from the +12 V
rail, however, they may also convert power from other rails.
3 Definitions/Terms/Acronyms
Required The status given to items within this design guide, which are required to
Recommended The status given to items within this design guide which are not required to
Optional The status given to items within this design guide, which are not required to
Autoranging A power supply that automatically senses and adjusts itself to the proper
CFM Cubic Feet per Minute (airflow).
Dropout A condition that allows the line voltage input to the power supply to drop to
meet SSI guidelines and a large majority of system applications.
meet SSI guidelines, however, are required by many system applications.
meet SSI guidelines, however, some system applications may optionally
use these features.
input voltage range (110 VAC or 220 VAC). No manual switches or
manual adjustments are needed.
below the minimum operating voltage.
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EPS12V Power Supply Design Guide, V2.0
Latch Off A power supply, after detecting a fault condition, shuts itself off. Even if the
Monotonically A waveform changes from one level to another in a steady fashion, without
Noise The periodic or random signals over frequency band of 0 Hz to 20 MHz.
Overcurrent A condition in which a supply attempts to provide more output current than
PFC Power Factor Corrected.
Ripple The periodic or random signals over a frequency band of 0 Hz to 20 MHz.
Rise Time Rise time is defined as the time it takes any output voltage to rise from
Sag The condition where the AC line voltage drops below the nominal voltage
Surge The condition where the AC line voltage rises above nominal voltage.
VSB or Standby Voltage An output voltage that is present whenever AC power is applied to the AC
MTBF Mean time between failure.
PWOK A typical logic level output signal provided by the supply that signals the
fault condition disappears the supply does not restart unless manual or
electronic intervention occurs. Manual intervention commonly includes
briefly removing and then reconnecting the supply, or it could be done
through a switch. Electronic intervention could be done by electronic
signals in the Server System.
intermediate retracement or oscillation.
the amount for which it is rated. This commonly occurs if there is a "short
circuit" condition in the load attached to the supply.
10% to 95% of its nominal voltage.
conditions.
inputs of the supply.
Server System that all DC output voltages are within their specified range.
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Top View
EPS12V Power Supply Design Guide, V2.0
4 Mechanical Overview
STATUS
Required
Three enclosure size options are defined to accommodate power levels from 400 to 700 watts. Recommended
power levels for each enclosure length are shown below. Refer to Figure 1 for details. The two rear mounting
tabs on the enclosure are OPTIONAL and may not be required for many systems.
Length Recommended power levels
140mm < 450W
180mm 450W to 600W
230mm > 600W
12 mm
55 mm
Optional mounting tab Optional mounting tab
11 mm
130 mm
110 mm
97.2 mm
15 mm
138 mm
Up
150 mm
Warning
Label
Airflow
AC
Inlet
86 mm
6x32 THREADED HOLE
(4x)
74 mm
Length
140 mm
Length
146 mm
+ 6mm
Label Area
16 mm
6 mm 114 mm
Figure 1: Enclosure Drawing
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4.1 Airflow Requirements
STATUS
Recommended
The power supply shall have a two-speed fan(s) and provide cooling to both the supply and the system. During
low-speed fan operation, the power supply must not exceed a noise level of 38 dBa measured at one meter on all
faces. At low fan speed, the power supply shall provide a minimum of 12 CFM of airflow with 0.003 inH2O of
system backpressure. At high fan speed, the power supply shall provide a minimum of 20 CFM with 0.006 inH2O
of system backpressure.
4.2 Temperature Requirements
STATUS
Recommended
The power supply shall operate within all specified limits over the Top temperature range. The average air
temperature difference (∆Tps ) from the inlet to the outlet of the power supply shall not exceed the values shown
below in Table 1. All airflow shall pass through the power supply and not over the exterior surfaces of the power
supply.
Table 1: Thermal Requirements
ITEM DESCRIPTION MIN MAX UNITS
Top Operating temperature range. 0 50 °C
T
Non-operating temperature range. -40 70 °C
non-op
The power supply must meet UL enclosure requirements for temperature rise limits. All sides of the power supply
with exception of the air exhaust side, must be classified as “Handle, knobs, grips, etc. held for short periods of
time only”.
EPS12V Power Supply Design Guide, V2.0
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EPS12V Power Supply Design Guide, V2.0
5 AC Input Requirements
STATUS
Required
The power supply shall incorporate universal power input with active power factor correction, which shall reduce
line harmonics in accordance with the EN61000-3-2 and JEIDA MITI standards.
5.1 AC Inlet Connector
STATUS
Required
The AC input connector shall be an IEC 320 C-14 power inlet. This inlet is rated for 15 A/250 VAC.
5.2 AC Input Voltage Specification
STATUS
Required
The power supply must operate within all specified limits over the following input voltage range. Harmonic
distortion of up to 10% THD must not cause the power supply to go out of specified limits. The power supply shall
operate properly at 85 VAC input voltage to guarantee proper design margins.
Table 2: AC Input Rating
PARAMETER MIN RATED MAX
Voltage (110) 90 V
Voltage (220) 180 V
Frequency 47 Hz 63 Hz
5.3 Input Under Voltage
STATUS
Required
The power supply shall contain protection circuitry such that application of an input voltage below the minimum
specified in Section 5.2 shall not cause damage to the power supply.
5.4 Efficiency
STATUS
Recommended
The following efficiency requirements are provided as a recommendation to allow for proper power supply cooling
when installed in a system.
100-127 V
rms
200-240 V
rms
140 V
rms
264 V
rms
rms
rms
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Table 3: Efficiency
Power Level Efficiency Airflow (reference)
450W 68% 20 CFM
550W 70% 20 CFM
650W 72% 24 CFM
5.5 AC Line Dropout
STATUS
Required
An AC line dropout is defined to be when the AC input drops to 0 VAC at any phase of the AC line for any length
of time. During an AC dropout of one cycle or less the power supply must meet dynamic voltage regulation
requirements over the rated load. An AC line dropout of one cycle or less shall not cause any tripping of control
signals or protection circuits. If the AC dropout lasts longer than one cycle, the power supply should recover and
meet all turn on requirements. The power supply must meet the AC dropout requirement over rated AC voltages,
frequencies, and output loading conditions. Any dropout of the AC line shall not cause damage to the power
supply.
5.6 AC Line Fuse
STATUS
Required
The power supply shall incorporate one input fuse on the LINE side for input over-current protection to prevent
damage to the power supply and meet product safety requirements. Fuses should be slow blow type or
equivalent to prevent nuisance trips. AC inrush current shall not cause the AC line fuse to blow under any
conditions. All protection circuits in the power supply shall not cause the AC fuse to blow unless a component in
the power supply has failed. This includes DC output load short conditions.
5.7 AC Inrush
STATUS
Required
The power supply must meet inrush requirements for any rated AC voltage, during turn on at any phase of AC
voltage, during a single cycle AC dropout condition, during repetitive ON/OFF cycling of AC, and over the
specified temperature range (Top). The peak inrush current shall be less than the ratings of its critical components
(including input fuse, bulk rectifiers, and surge limiting device).
STATUS
Recommended
An additional inrush current limit is recommended for some system applications that require multiple systems on a
single AC circuit. AC line inrush current shall not exceed 50 A peak for one-quarter of the AC cycle, after which,
the input current should be no more than the specified maximum input current from Table 2.
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EPS12V Power Supply Design Guide, V2.0
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