Enhance EPS1U Version 2.1 Power Supply Design Guide
SSI
EPS1U
Power Supply Design Guide
A Server System Infrastructure (SSI) Specification
For 1U Rack Chassis Power Supplies
Revision 2.1
Revision History
Orig./Rev. Description of Changes Date
2.0 Added 355mm length power supply form factor. Changed layout of form factor
descriptions. Deleted temp rise requirements from thermal section. Added efficiency
recommendations and airflow ref for each power level. Added 450W and 500W
power levels. Added 450W and 500W connector pinout. Updated step load
requirements. Updated 240VA requirements. Updated signal description for PSON#,
PWOK, and ACWarning.
2.1
Section 4.2 - Added optional fan placement to alternate enclosure drawing
Section 4.4 - Changed operating temperature to 45°C from 50°C
Section 6.4 - Changed output load rating tables
Defined one load range per output level (vs. two)
Increased +12V currents for 450 & 500W supplies
Section 6.6 - Adjusted transient load requirements
Section 7.2 – Changed over current protection table (added +12V3 peak value)
8/21/2002
5/18/2003
SSI
EPS1U Power Supply Design Guide, V2.1
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, NEC
Corporation, Dell Computer Corporation, Data General a division of EMC Corporation, Compaq Computer Corporation, 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 DAMAGES, 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 are 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, 2001 – 2003.
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EPS1U Power Supply Design Guide, V2.1
Contents
1 Purpose.......................................................................................................................................................... 5
2 Conceptual Overview ................................................................................................................................... 5
3 Definitions/Terms/Acronyms....................................................................................................................... 6
4 Mechanical Overview ................................................................................................................................... 7
4.1 Card Edge Form Factor ...................................................................................................................... 7
4.2 Wire Harness ...................................................................................................................................... 8
4.3 Airflow Requirements.......................................................................................................................... 9
4.4 Temperature Requirements................................................................................................................ 9
5 AC Input Requirements.............................................................................................................................. 10
5.1 AC Inlet Connector............................................................................................................................ 10
5.2 AC Input Voltage Specification ......................................................................................................... 10
5.3 Input Under Voltage.......................................................................................................................... 10
5.4 Efficiency........................................................................................................................................... 11
5.5 AC Line Dropout ............................................................................................................................... 11
5.6 AC Line Fuse .................................................................................................................................... 12
5.7 AC Inrush .......................................................................................................................................... 12
5.8 AC Line Transient Specification........................................................................................................ 13
5.9 AC Line Fast Transient Specification................................................................................................ 13
6 DC Output Specification ............................................................................................................................ 14
6.1 Connector ......................................................................................................................................... 14
6.1.1 Power Connector (125W, 250W, 350W, 400W) .................................................................. 14
6.1.2 Power Connector (450W, 500W) ......................................................................................... 16
6.2 Grounding ......................................................................................................................................... 18
6.3 Remote Sense .................................................................................................................................. 18
6.4 Output Power/Currents ..................................................................................................................... 18
6.4.1 Standby Outputs................................................................................................................... 21
6.5 Voltage Regulation............................................................................................................................ 21
6.6 Dynamic Loading .............................................................................................................................. 21
6.7 Capacitive Loading ........................................................................................................................... 22
6.8 Ripple / Noise.................................................................................................................................... 22
6.9 Timing Requirements........................................................................................................................ 23
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 AC Warning....................................................................................................................................... 29
8.4 Field Replacement Unit (FRU) Signals............................................................................................. 30
8.4.1 FRU Data.............................................................................................................................. 30
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EPS1U Power Supply Design Guide, V2.1
8.4.2 FRU Data Format .................................................................................................................30
8.5 LED Indicator .................................................................................................................................... 32
9 MTBF ............................................................................................................................................................ 33
10 Agency Requirements................................................................................................................................ 33
Figures
Figure 1: Enclosure Drawing .................................................................................................................................... 7
Figure 2: Alternate Enclosure Drawing..................................................................................................................... 8
Figure 3: Edge Finger Layout ................................................................................................................................. 15
Figure 4: Edge Finger Layout ................................................................................................................................. 17
Figure 5: Output Voltage Timing............................................................................................................................. 23
Figure 6: Turn On/Off Timing (Signal Power Supply)............................................................................................. 25
Figure 7: PSON# Signal Characteristics ................................................................................................................ 28
Tables
Table 1: Definitions, Terms, and Acronyms (listed alphabetically)........................................................................... 6
Table 2: Thermal Requirements ............................................................................................................................... 9
Table 3: AC Input Rating ........................................................................................................................................ 10
Table 4: Efficiency .................................................................................................................................................. 11
Table 5: AC Line Sag Transient Performance........................................................................................................ 13
Table 6: AC Line Surge Transient Performance .................................................................................................... 13
Table 7: Edge Finger Pinout................................................................................................................................... 14
Table 8: Edge Finger Pinout................................................................................................................................... 16
Table 9: 125 W Load Ratings ................................................................................................................................. 19
Table 10: 250 W Load Ratings ............................................................................................................................... 19
Table 11: 350 W Load Ratings ............................................................................................................................... 19
Table 12: 400 W Load Ratings ............................................................................................................................... 20
Table 13: 450 W Load Ratings ............................................................................................................................... 20
Table 14: 500 W Load Ratings ............................................................................................................................... 20
Table 15: Voltage Regulation Limits....................................................................................................................... 21
Table 16: Optional +5V Regulation Limits .............................................................................................................. 21
Table 17: Transient Load Requirements ................................................................................................................ 22
Table 18: Capacitive Loading Conditions............................................................................................................... 22
Table 19: Ripple and Noise .................................................................................................................................... 22
Table 20: Output Voltage Timing............................................................................................................................ 23
Table 21: Turn On/Off Timing................................................................................................................................. 24
Table 22: Over Current Protection.......................................................................................................................... 26
Table 23: Over Current Protection.......................................................................................................................... 27
Table 24: Over Voltage Limits ................................................................................................................................ 27
Table 25: PSON# Signal Characteristic .................................................................................................................. 28
Table 26: PWOK Signal Characteristics................................................................................................................. 29
Table 27: ACWarning Signal Characteristics ......................................................................................................... 29
Table 28: FRU Device Information ......................................................................................................................... 30
Table 29: FRU Device Product Information Area ................................................................................................... 30
Table 30: FRU Device MultiRecord Area ............................................................................................................... 31
Table 31: LED Indicators ........................................................................................................................................ 32
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EPS1U Power Supply Design Guide, V2.1
1
Purpose
This specification defines non-redundant power supplies that support 1U rack mount entry server systems. The
entry-level power supply is not intended to be a hot swap type of power supply. The parameters of this supply are
defined in this specification for open industry use. This specification defines power supplies ranging from 125 W
to 500 W, with six outputs: 3.3 V, 5 V, 12 V, -12 V, and 5 VSB. The form factor fits into a 1U system and
provides a wire harness or docking solution for output connections. An IEC connector is provided on the external
face for AC input to the power supply. The power supply contains fans for cooling, while meeting acoustic
requirements.
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
• 5V 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.
The bulk power system may be an n+1 redundant power system or a non-redundant power system.
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EPS1U Power Supply Design Guide, V2.1
3 Definitions/Terms/Acronyms
Table 1: Definitions, Terms, and Acronyms (listed alphabetically)
Required
Recommended
Optional
Full Ranging
CFM
Dropout
Latch Off
Monotonically
MTBF
Noise
Overcurrent
PFC
PWOK
Ripple
Rise Time
Sag
Surge
VSB or Standby Voltage
The status given to items within this design guide, which are required to
meet SSI guidelines and a large majority of system applications.
The status given to items within this design guide which are not required to
meet SSI guidelines, however, are required by many system applications.
The status given to items within this design guide, which are not required to
meet SSI guidelines, however, some system applications may optionally
use these features.
A full-ranging power supply automatically senses and adjusts itself to the
proper input voltage range (110 VAC or 220 VAC). No manual switches or
manual adjustments are needed.
Cubic Feet per Minute (airflow).
A condition that allows the line voltage input to the power supply to drop to
below the minimum operating voltage.
A power supply, after detecting a fault condition, shuts itself off. Even if 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.
A waveform changes from one level to another in a steady fashion, without
intermediate retracement or oscillation.
Mean time between failure
The periodic or random signals over frequency band of 0 Hz to 20 MHz.
A condition in which a supply attempts to provide more output current than
the amount for which it is rated. This commonly occurs if there is a "short
circuit" condition in the load attached to the supply.
Power Factor Corrected.
A typical logic level output signal provided by the supply that signals the
Server System that all DC output voltages are within their specified range.
The periodic or random signals over a frequency band of 0 Hz to 20 MHz.
Rise time is defined as the time it takes any output voltage to rise from
10% to 95% of its nominal voltage.
The condition where the AC line voltage drops below the nominal voltage
conditions.
The condition where the AC line voltage rises above nominal voltage.
An output voltage that is present whenever AC power is applied to the AC
inputs of the supply.
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EPS1U Power Supply Design Guide, V2.1
4 Mechanical Overview
STATUS
Required
There are three physical sizes of the power supply enclosure intended to accommodate different power levels
from 125W up to 550W. Two output connector designs are defined, also. A card edge solution provides ease of
installation and removal, while the wire harness design provides a traditional cabled solution. The enclosure of
the entry 1U power supply is designed for use in 1U rack mounted systems.
4.1 Card Edge Form Factor
The card edge form factor is intended to allow users and manufacturers easy installation and removal of the
power supply into the system. Refer to Figure 1 for details. There are three different lengths for use with different
power levels. The recommended length for each power level is shown below.
Length Recommended power levels
215mm 125W – 230W
300mm 250W – 450W
40.0
355mm 450W – 550W
+/- 0.
53.0
+/- 0.
106.0
Bi-Color LED
(PWR/Fail)
+0.2/-0.
16.4
Fan
Exterior Face View
+/- 0.
IEC Connector
Center Line
C I/P
Fan
Top View
IEC Connector
+0/-0.
IEC Connector
Center Line
80.92
12.54
+/-0.
+/-0.
8.5
Length
Side View
ll dimensions are in millimeters.
+/-0.
5.0
62 32
1
31
Interior Face View
Figure 1: Enclosure Drawing
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EPS1U Power Supply Design Guide, V2.1
4.2 Wire Harness
STATUS
Low Power Form Factor
Systems may require a wire harness connection directly from the power supply to the system. Figure 2 shows the
wire harness version details. Refer to the EPS2U specification on the SSI web site (http://www.ssiforum.org) for
possible output connector configurations. Due to different system board layouts the wire harness length may
vary.
40.0
Bi-Color LED
(PWR/Fail)
+0.2/-0.
16.4
Fan
Exterior Face
+/- 0.
+/- 0.
53.0
IEC Connector
Center Line
AC I/P
Fan
106.0
+/- 0.
IEC Connector
IEC Connector
Center Line
Length
ll dimensions are in millimeters.
Optional fan
placement
Wire
harness exit
location
Interior Face
Figure 2: Alternate Enclosure Drawing
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EPS1U Power Supply Design Guide, V2.1
4.3 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 shall 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 6 CFM of airflow with 0.003 inH2O of
system backpressure. At high fan speed, the power supply shall provide a minimum of 10 CFM with 0.006 inH2O
of system backpressure.
4.4 Temperature Requirements
STATUS
Recommended
The power supply shall operate within all specified limits over the Top temperature range. All airflow shall pass
through the power supply and not over the exterior surfaces of the power supply.
Table 2: Thermal Requirements
Item Description MIN MAX Units
Top Operating temperature range. 0 50
T
Non-operating temperature range. -40 70
non-op
The power supply must meet UL enclosure requirements for temperature rise limits. All sides of the power
supply, with exception to the air exhaust side, must be classified as “Handle, knobs, grips, etc. held for short
periods of time only”.
°C
°C
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EPS1U Power Supply Design Guide, V2.1
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 3: AC Input Rating
PARAMETER MIN RATED MAX
Voltage (110) 90 V
Voltage (220) 180 V
Frequency 47 Hz 63 Hz
100-127 V
rms
200-240 V
rms
140 V
rms
264 V
rms
rms
rms
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.
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