SSI
EPS1U Power Supply Design Guide, V2.0
EPS1U
Power Supply Design Guide
A Server System Infrastructure (SSI) Specification
For 1U Rack Chassis Power Supplies
Version 2.0
Revision History
Orig./Rev. Description of Changes Date
1.1 Initial release of EPS1U specification
2.0 Added higher power levels for 400W, 450W, and 500W power supplies.
Added a longer 355mm form factor for the 450W and 500W power levels.
Added requirements for the higher power levels: 3rd 240VA channel, output connector,
efficiency, and output loading.
Updated requirements for PSON#, PWOK, and ACWarning.
9/24/2002
Page 1 of 34
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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 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 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, 2001.
EPS1U Power Supply Design Guide, V2.0
Page 2 of 34
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EPS1U Power Supply Design Guide, V2.0
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..................................................................................................................11
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 ...................................................................................................22
6.5 Voltage Regulation.................................................................Error! Bookmark not defined.
6.6 Dynamic Loading.............................................................................................................22
6.7 Capacitive Loading...........................................................................................................23
6.8 Ripple / Noise..................................................................................................................23
6.9 Timing Requirements........................................................................................................24
7 Protection Circuits....................................................................................................................27
7.1 Current Limit...................................................................................................................27
7.2 240VA Protection.............................................................................................................27
7.3 Over Voltage Protection....................................................................................................28
7.4 Over Temperature Protection.............................................................................................28
8 Control and Indicator Functions................................................................................................29
8.1 PSON#...........................................................................................................................29
8.2 PWOK (Power OK)...........................................................................................................30
8.3 ACWarning.....................................................................................................................31
8.4 Field Replacement Unit (FRU) Signals ................................................................................32
8.4.1 FRU Data.............................................................................................................32
8.4.2 FRU Data Format..................................................................................................32
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8.5 LED Indicator..................................................................................................................34
EPS1U Power Supply Design Guide, V2.0
9 MTBF.......................................................................................................................................34
10 Agency Requirements...............................................................................................................35
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............................................................................................................24
Figure 6: Turn On/Off Timing (Signal Power Supply).................................................................................26
Figure 7: PSON# Signal Characteristics .................................................................................................29
Tables
Table 1: Definitions, Terms, and Acronyms (listed alphabetically).................................................................6
Table 2: Thermal Requirements ..............................................................................................................9
Table 3: AC Input Voltage 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 ..............................................................................................................20
Table 12: 400 W Load Ratings ..............................................................................................................20
Table 13: 450 W Load Ratings ..............................................................................................................21
Table 14: 500 W Load Ratings ..............................................................................................................21
Table 15: Voltage Regulation Limits.......................................................................................................22
Table 16: Optional +5V Regulation Limits ...............................................................................................22
Table 17: Transient Load Requirements.................................................................................................23
Table 18: Capacitive Loading Conditions ................................................................................................23
Table 19: Ripple and Noise...................................................................................................................23
Table 20: Output Voltage Timing...........................................................................................................24
Table 21: Turn On/Off Timing................................................................................................................25
Table 22: Over Current Protection.........................................................................................................27
Table 23: Over Current Protection.........................................................................................................28
Table 24: Over Voltage Limits...............................................................................................................28
Table 25: PSON# Signal Characteristic...................................................................................................29
Table 26: PWOK Signal Characteristics..................................................................................................30
Table 27: ACWarning Signal Characteristics ...........................................................................................31
Table 28: FRU Device Information.........................................................................................................32
Table 29: FRU Device Product Information Area......................................................................................32
Table 30: FRU Device MultiRecord Area.................................................................................................33
Table 31: LED Indicators......................................................................................................................34
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EPS1U Power Supply Design Guide, V2.0
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 a 125W, 250 W and 350 W power
supply 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, V2.0
3 Definitions/Terms/Acronyms
Table 1: Definitions, Terms, and Acronyms (listed alphabetically)
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
Full Ranging A full-ranging power supply automatically senses and adjusts itself to the
CFM Cubic Feet per Minute (airflow).
Dropout A condition that allows the line voltage input to the power supply to drop to
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
MTBF Mean time between failure
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.
PWOK A typical logic level output signal provided by the supply that signals the
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
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.
proper input voltage range (110 VAC or 220 VAC). No manual switches or
manual adjustments are needed.
below the minimum operating voltage.
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.
Server System that all DC output voltages are within their specified range.
10% to 95% of its nominal voltage.
conditions.
inputs of the supply.
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EPS1U Power Supply Design Guide, V2.0
Length
8.5
+/-0.3
Interior Face View
+0.2/-0.5
Exterior Face View
106.0
+/- 0.2
80.92
+0/-0.05
12.54
+/-0.3
5.0
+/-0.3
IEC Connector
AC I/P
Bi-
Color LED
IEC Connector
53.0
+/- 0.2
16.4
+/- 0.2
IEC Connector
Top View
Side View
4 Mechanical Overview
STATUS
Required
There are two physical sizes of the power supply enclosure intended to accommodate different power levels from
125W up to 500W. There are two output connector designs. A card edge solution to provide ease of installation
and removal and a wire harness to provide a traditional cabled solution. The chassis for 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, 250W
300mm 250W, 350W, 400W
355mm 450W, 500W
Center Line
(PWR/Fail)
40.0
Center Line
Fan
Fan
All dimensions are in millimeters.
Figure 1: Enclosure Drawing
62 32
1
31
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EPS1U Power Supply Design Guide, V2.0
Length
Interior Face
+0.2/-0.5
Exterior Face
106.0
+/- 0.2
IEC Connector
AC I/P
Bi-
Color LED
IEC Connector
53.0
+/- 0.2
16.4
+/- 0.2
IEC Connector
harness exit
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 Entry Electronics Bay Specification at the SSI web site
(http://www.ssiforum.org/docs/entry_elecbay_spec_v2_0.pdf) for possible output connector configurations. Due
to different system board layouts the wire harness length may vary.
Center Line
(PWR/Fail)
40.0
Center Line
Fan
Fan
All dimensions are in millimeters.
Figure 2: Alternate Enclosure Drawing
Wire
location
Page 8 of 34
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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.
Item Description MIN MAX Units
Top Operating temperature range. 0 45
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”.
Table 2: Thermal Requirements
EPS1U Power Supply Design Guide, V2.0
°C
°C
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EPS1U 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 3: AC Input Voltage 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.
100-127 V
rms
200-240 V
rms
140 V
rms
264 V
rms
rms
rms
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EPS1U Power Supply Design Guide, V2.0
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.
Power Level Efficiency Airflow (reference)
125W 65% 6 CFM
250W 68% 10 CFM
350W 72% 11 CFM
400W 74% 11 CFM
450W 74% 13 CFM
500W 75% 13 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.
STATUS
Optional
Table 4 Efficiency
Page 11 of 34
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Some system applications may require a second input fuse in the NEUTRAL side of the AC input. In this case
two fuses would be required; one in the LINE side and one in the NEUTRAL side of the AC inlet to the power
supply.
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 30 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 3.
EPS1U Power Supply Design Guide, V2.0
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EPS1U Power Supply Design Guide, V2.0
5.8 AC Line Transient Specification
STATUS
Recommended
AC line transient conditions shall be defined as “sag” and “surge” conditions. Sag conditions (also referred to as
“brownout” conditions) will be defined as the AC line voltage dropping below nominal voltage. Surge will be
defined as the AC line voltage rising above nominal voltage.
The power supply shall meet the requirements under the following AC line sag and surge conditions.
Duration Sag Operating AC Voltage Line Frequency Performance Criteria
Continuous 10% Nominal AC Voltage ranges 50/60 Hz No loss of function or performance
0 to 1 AC cycle 100% Nominal AC Voltage ranges 50/60 Hz No loss of function or performance
> 1 AC cycle >10% Nominal AC Voltage ranges 50/60 Hz Loss of function acceptable, self-
Duration Surge Operating AC Voltage Line Frequency Performance Criteria
Continuous 10% Nominal AC Voltages 50/60 Hz No loss of function or performance
0 to ½ AC cycle 30% Mid-point of nominal AC
5.9 AC Line Fast Transient Specification
STATUS
Recommended
The power supply shall meet the EN61000-4-5 directive and any additional requirements in IEC1000-4-5:1995
and the Level 3 requirements for surge-withstand capability, with the following conditions and exceptions:
• These input transients must not cause any out-of-regulation conditions, such as overshoot and
undershoot, nor must it cause any nuisance trips of any of the power supply protection circuits.
• The surge-withstand test must not produce damage to the power supply.
• The supply must meet surge-withstand test conditions under maximum and minimum DC-output load
conditions.
Table 5: AC Line Sag Transient Performance
recoverable
Table 6: AC Line Surge Transient Performance
Voltages
50/60 Hz No loss of function or performance
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EPS1U Power Supply Design Guide, V2.0
6 DC Output Specification
6.1 Connector
STATUS
Required
6.1.1 Power Connector (125W, 250W, 350W, 400W)
The power supply uses a blind mating type connector with edge fingers (see Figure 1) to connect the power
supply’s output voltages and signals to a connector located in the system. The card edge pin assignments are
listed in Table 7. Figure 3 shows the card edge layout for the power supply. The connector located in the system
is an AMP 1364999-1 or equivalent.
Signals that can be defined as low true or high true use the following convention: signal# = low true. Reserved
pins are reserved for future use.
Description Pin# Pin# Description
-12V 1 62 PSON#
PWOK 2 61 SDA
Reserved 3 60 SCL
ACWarning 4 59 Reserved
5VSB 5 58 ReturnS
Removed pin 6 57 Reserved
Reserved 7 56 Reserved
Reserved 8 55 3.3VS
Reserved 9 54 Reserved
Reserved 10 53 Reserved
12V2 11 52 12V2
Keying notch between positions 11 and 12
12V2 12 51 12V2
12V2 13 50 12V2
12V1 14 49 12V1
12V1 15 48 12V1
12V1 16 47 12V1
Ground 17 46 Ground
Ground 18 45 Ground
Ground 19 44 Ground
Ground 20 43 Ground
Ground 21 42 Ground
Ground 22 41 Ground
Ground 23 40 Ground
Ground 24 39 Ground
Ground 25 38 Ground
5V 26 37 5V
5V 27 36 5V
5V 28 35 5V
3.3V 29 34 3.3V
3.3V 30 33 3.3V
3.3V 31 32 3.3V
Table 7: Edge Finger Pinout
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5VSB
ACWarning
PWOK
3.3V
5V
12V2
-12V
3.3VS ReturnS
Reserved
Removed pin (NC)
Reserved
Reserved
12V2
GROUND
5V
3.3V
d
12V1
12V1
Reserved
Reserved
29.03 +/-0.05
9 spaces @ 2.54
7.62 MIN
GROUND
All dimensions are in millimeters.
PSON#
SCL
Reserved
SDA
62
1.27 +/-0.05
1
Reserve
Top View of Power Supply
Reserved
Reserved
Reserved
1.27
1.07 +/-0.05
Bottom view of power supply
Figure 3: Edge Finger Layout
Keying Notch
6.35 +/-0.05
6.35 +/-0.05
EPS1U Power Supply Design Guide, V2.0
21.59 +/-0.05
6.35 +/-0.05
6.35 +/-0.05
51.89 +/-0.05
1.6
32
0.38 x 45
1.57 x 45
31
5.08 MIN
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EPS1U Power Supply Design Guide, V2.0
6.1.2 Power Connector (450W, 500W)
The higher power level version of the power supply uses the same connector type but a different pin assignment
and keying. The card edge pin assignments are listed in Table 7. Figure 3 shows the card edge layout for the
high power supply. The connector located in the system is an AMP 1364999-1 or equivalent with the keying
location moved.
Signals that can be defined as low true or high true use the following convention: signal# = low true. Reserved
pins are reserved for future use.
Description Pin# Pin# Description
-12V 1 62 PSON#
PWOK 2 61 SDA
ACWarning 3 60 SCL
Removed pin 4 59 ReturnS
5VSB 5 58 3.3VS
Reserved 6 57 Reserved
12V3 7 56 12V3
12V3 8 55 12V3
12V3 9 54 12V3
12V2 10 53 12V2
12V2 11 52 12V2
12V2 12 51 12V2
12V1 13 50 12V1
12V1 14 49 12V1
12V1 15 48 12V1
Ground 16 47 Ground
Ground 17 46 Ground
Ground 18 45 Ground
Ground 19 44 Ground
Ground 20 43 Ground
Ground 21 42 Ground
Ground 22 41 Ground
Ground 23 40 Ground
Ground 24 39 Ground
Ground 25 38 Ground
5V 26 37 5V
5V 27 36 5V
5V 28 35 5V
3.3V 29 34 3.3V
3.3V 30 33 3.3V
3.3V 31 32 3.3V
Table 8: Edge Finger Pinout
Keying notch between pins 6 and 7
Page 16 of 34
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5VSB
ACWarning
PWOK
3.3V
5V
12V2
-12V
ReturnS
3.3VS
Removed pin (NC)
Reserved
12V1
GROUND
5V
3.3V
12V3 12V2
18.87 +/-0.05
5 spaces @ 2.54
6.35
0.05
7.62 MIN
12V1
6.35
6.35
12V3
All dimensions are in millimeters.
SCL
PSON#
SDA
62
1.27 +/-0.05
1
Reserved
+/-0.05
1.27
1.07 +/-0.05
Keying Notch
+/-0.05
Top View of Power Supply
+/-0.05
24.13 +/-
6.35 +/-0.05
62.05 +/-0.05
Bottom view of power supply
Figure 4: Edge Finger Layout
EPS1U Power Supply Design Guide, V2.0
1.6
GROUND
32
6.35 +/-0.05
0.38 x 45
1.57 x 45
31
5.08 MIN
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EPS1U Power Supply Design Guide, V2.0
6.2 Grounding
STATUS
Required
The ground of the pins of the power supply wire harness provides the power return path. The wire harness
ground pins shall be connected to safety ground (power supply enclosure).
6.3 Remote Sense
STATUS
Optional
The power supply may have remote sense return (ReturnS) to regulate out ground drops for all output voltages;
+3.3 V, +5 V, +12 V1, +12 V2, -12 V, and 5 VSB. The power supply may use remote sense (3.3VS) to regulate
out drops in the system for the +3.3 V output. The +5 V, +12 V1, +12 V2, –12 V, and 5 VSB outputs only use
remote sense referenced to the ReturnS signal. The remote sense input impedance to the power supply must be
greater than 200 Ω on 3.3 VS and ReturnS. This is the value of the resistor connecting the remote sense to the
output voltage internal to the power supply. Remote sense must be able to regulate out a minimum of 200 mV
drop on the +3.3 V output. The remote sense return (ReturnS) must be able to regulate out a minimum of 200 mV
drop in the power ground return. The current in any remote sense line shall be less than 5 mA to prevent voltage
sensing errors. The power supply must operate within specification over the full range of voltage drops from the
power supply’s output connector to the remote sense points.
6.4 Output Power/Currents
STATUS
Recommendations
The following tables define three power and current ratings for a 125W, 250 W and a 350 W power supply. These
were selected to cover different types of systems and configurations. The 125W power level is targeted for use in
“today’s” low power server systems. The 250W power level is targeted for use in “today’s” higher power 1U
server systems. The 350W power level is directed at “tomorrow’s” higher power 1U server systems. The
combined output power of all outputs shall not exceed the rated output power. The tables show the load ranges
for each of the two power supply power levels. The power supply must meet both static and dynamic voltage
regulation requirements for the minimum loading conditions.
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EPS1U Power Supply Design Guide, V2.0
Table 9: 125 W Load Ratings
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.5 A 6 A
+5 V 0.5 A 12 A
+12 V1 0.25 A 3 A 6 A
+12 V2 Not used for 125W version.
-12 V 0 A 0.2 A
+5 VSB 0.1 A 1.0 A
1. Maximum continuous total DC output power should not exceed 125 W.
2. Peak total DC output power should not exceed 161 W.
3. Peak power and current loading shall be supported for a minimum of 12 seconds.
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 1.5 A 16 A
+5 V 1.0 A 12 A
+12 V1 1.5 A 16 A See note 2
+12 V2 0.5 A 10 A See note 2
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.2 A 5.0 A
+5 V 0.2 A 5.0 A
+12 V1 0.2 A 8.0 A
+12 V2 0.2 A 2.0 A 4.0 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
1 Maximum continuous total DC output power should not exceed 250 W.
2 Peak load on the combined 12 V output shall not exceed 22 A.
3 Maximum load on the combined 12 V output shall not exceed 18 A.
4 Peak total DC output power should not exceed 300 W.
5 Peak power and current loading shall be supported for a minimum of 12 seconds.
Load Range
Table 10: 250 W Load Ratings
Load Range 1
Load Range 2
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EPS1U Power Supply Design Guide, V2.0
Table 11: 350 W Load Ratings
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 1.5 A 16 A
+5 V 1.0 A 12 A
+12 V1 1.5 A 18 A 22 A
+12 V2 1.5 A 16 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.2 A 5.0 A
+5 V 0.2 A 5.0 A
+12 V1 0.2 A 8.0 A 11 A
+12 V2 0.2 A 5.0 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
1. Maximum continuous total DC output power should not exceed 350 W.
2. Peak load on the combined 12 V output shall not exceed 32 A.
3. Maximum load on the combined 12 V output shall not exceed 28 A.
4. Peak total DC output power should not exceed 400 W.
5. Peak power shall be supported for a minimum of 12 seconds.
6. Peak +12 V1 current shall be supported for a minimum of 0.5 seconds.
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 1.5 A 16 A
+5 V 1.0 A 12 A
+12 V1 1.5 A 18 A 22 A
+12 V2 1.5 A 16 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.2 A 5.0 A
+5 V 0.2 A 5.0 A
+12 V1 0.2 A 8.0 A 11 A
+12 V2 0.2 A 5.0 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
1. Maximum continuous total DC output power should not exceed 400 W.
2. Peak load on the combined 12 V output shall not exceed 34 A.
3. Maximum load on the combined 12 V output shall not exceed 30 A.
4. Peak total DC output power should not exceed 450 W.
5. Peak power and current loading shall be supported for a minimum of 12 seconds.
6. Combined 3.3V and 5V power shall not exceed 90W.
Load Range 1
Load Range 2
Table 12: 400 W Load Ratings
Load Range 1
Load Range 2
Page 20 of 34
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EPS1U Power Supply Design Guide, V2.0
Table 13: 450 W Load Ratings
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 1.5 A 16 A
+5 V 1.0 A 12 A
+12 V1 1.5 A 9 A 15 A
+12 V2 1.5 A 9 A 15 A
+12 V3 1.5 A 14 A 18 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.2 A 5.0 A
+5 V 0.2 A 5.0 A
+12 V1 0.2 A 4.0 A 7 A
+12 V2 0.2 A 4.0 A 7 A
+12 V3 0.2 A 5.0 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
7. Maximum continuous total DC output power should not exceed 450 W.
8. Peak load on the combined 12 V output shall not exceed 36 A.
9. Maximum load on the combined 12 V output shall not exceed 32 A.
10. Peak total DC output power should not exceed 500 W.
11. Peak power and current loading shall be supported for a minimum of 12 seconds.
12. Combined 3.3V and 5V power shall not exceed 90W.
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 1.5 A 16 A
+5 V 1.0 A 12 A
+12 V1 1.5 A 11 A 15 A
+12 V2 1.5 A 11 A 15 A
+12 V3 1.5 A 14 A 18 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
Voltage Minimum Continuous Maximum Continuous Peak
+3.3 V 0.2 A 5.0 A
+5 V 0.2 A 5.0 A
+12 V1 0.2 A 4.0 A 7 A
+12 V2 0.2 A 4.0 A 7 A
+12 V3 0.2 A 5.0 A
-12 V 0 A 0.5 A
+5 VSB 0.1 A 2.0 A
13. Maximum continuous total DC output power should not exceed 500 W.
14. Peak load on the combined 12 V output shall not exceed 39 A.
15. Maximum load on the combined 12 V output shall not exceed 35 A.
16. Peak total DC output power should not exceed 550 W.
17. Peak power and current loading shall be supported for a minimum of 12 seconds.
18. Combined 3.3V and 5V power shall not exceed 90W.
Load Range 1
Load Range 2
Table 14: 500 W Load Ratings
Load Range 1
Load Range 2
Page 21 of 34
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6.4.1 Standby Outputs
EPS1U Power Supply Design Guide, V2.0
STATUS
Required
The 5 VSB output shall be present when an AC input greater than the power supply turn on voltage is applied.
6.5 Voltage Regulation
STATUS
Required
The power supply output voltages must stay within the following voltage limits when operating at steady state and
dynamic loading conditions. These limits include the peak-peak ripple/noise specified in Section 6.8. All outputs
are measured with reference to the return remote sense (ReturnS) signal. The 5 V, 12 V1, 12 V2, –12 V and 5
VSB outputs are measured at the power supply connectors referenced to ReturnS. The +3.3 V is measured at its
remote sense signal (3.3 VS) located at the signal connector.
Parameter MIN NOM MAX Units Tolerance
+3.3 V +3.20 +3.30 +3.46 V
+5 V +4.80 +5.00 +5.25 V
+12 V1 +11.52 +12.00 +12.60 V
+12 V2 +11.52 +12.00 +12.60 V
-12 V -11.40 -12.20 -13.08 V
+5 VSB +4.85 +5.00 +5.25 V
Table 15: Voltage Regulation Limits
+5/-3%
rms
+5/-4%
rms
+5/-4%
rms
+5/-4%
rms
+9/-5%
rms
+5/-4%
rms
STATUS
Optional
Some system applications may require tighter regulation limits on the +5 V output. The optional regulation limits
are shown below.
Parameter MIN NOM MAX Units Tolerance
+5 V +4.85 +5.00 +5.25 V
6.6 Dynamic Loading
Table 16: Optional +5V Regulation Limits
+5/-3%
rms
STATUS
Required
The output voltages shall remain within the limits specified in Table 15 for the step loading and within the limits
specified in Table 17 for the capacitive loading. The load transient repetition rate shall be tested between 50 Hz
and 5 kHz at duty cycles ranging from 10%-90%. The load transient repetition rate is only a test specification.
The ∆ step load may occur anywhere within the MIN load to the MAX load shown in Table 10 and
Page 22 of 34
SSI
Table 11.
Output
+3.3 V 30% of max load
+5 V 30% of max load
12 V1 65% of max load
12 V2 65% of max load
12V 3 65% of max load
+5 VSB 25% of max load
6.7 Capacitive Loading
STATUS
Required
The power supply shall be stable and meet all requirements with the following capacitive loading ranges.
6.8 Ripple / Noise
STATUS
Required
The maximum allowed ripple/noise output of the power supply is defined in Table 19 below. This is measured
over a bandwidth of 0 Hz to 20 MHz at the power supply output connectors. A 10 µF tantalum capacitor in
parallel with a 0.1 µF ceramic capacitor are placed at the point of measurement.
+3.3 V +5 V +12 V -12 V +5 VSB
50 mVp-p 50 mVp-p 120 mVp-p 120 mVp-p 50 mVp-p
Table 17: Transient Load Requirements
∆ Step Load Size
Table 18: Capacitive Loading Conditions
Output MIN MAX Units
+3.3 V 10 6,800
+5 V 10 4,700
+12 V 10 11,000
-12 V 1 350
+5 VSB 1 350
Table 19: Ripple and Noise
Load Slew Rate Capacitive Load
0.5 A/µs 100 µF
0.5 A/µs 100 µF
1 A/µs 0 µF
1 A/µs 0 µF
1 A/µs 0 µF
0.5 A/µs 1 µF
EPS1U Power Supply Design Guide, V2.0
µF
µF
µF
µF
µF
Page 23 of 35
SSI
Vout
10%
Vout
T
T
T
V1 V2
V3
V4
EPS1U Power Supply Design Guide, V2.0
6.9 Timing Requirements
STATUS
Required
These are the timing requirements for the power supply operation. The output voltages must rise from 10% to
within regulation limits (T
rise at about the same time. All outputs must rise monotonically. The +5 V output needs to be greater than the
+3.3 V output during any point of the voltage rise. The +5 V output must never be greater than the +3.3V output
by more than 2.25 V. Each output voltage shall reach regulation within 50 ms (T
on of the power supply. Each output voltage shall fall out of regulation within 400 ms (T
during turn off. Figure 5 and Figure 6 show the turn ON and turn OFF timing requirements. In Figure 6 the timing
is shown with both AC and PSON# controlling the ON/OFF of the power supply.
Item Description MIN MAX Units
T
vout_rise
T
vout_on
T
vout_off
Output voltage rise time from each main output. 5 70 ms
All main outputs must be within regulation of each
other within this time.
All main outputs must leave regulation within this
time.
) within 5 to 70 ms. The +3.3 V, +5 V and +12 V output voltages should start to
vout_rise
) of each other during turn
vout_on
) of each other
vout_off
Table 20: Output Voltage Timing
50 ms
400 ms
vout_rise
vout_on
vout_off
Figure 5: Output Voltage Timing
Page 24 of 35
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EPS1U Power Supply Design Guide, V2.0
Item Description MIN MAX Units
Tsb_on_delay
T ac_on_delay
Tvout_holdup
Tpwok_holdup
Tpson_on_delay
T pson_pwok
Tpwok_on
T pwok_off
Tpwok_low
Tsb_vout
Delay from AC being applied to 5 VSB being
within regulation.
Delay from AC being applied to all output
voltages being within regulation.
Time all output voltages stay within regulation
after loss of AC.
Delay from loss of AC to deassertion of PWOK 17 ms
Delay from PSON# active to output voltages
within regulation limits.
Delay from PSON# deactive to PWOK being
deasserted.
Delay from output voltages within regulation
limits to PWOK asserted at turn on.
Delay from PWOK deasserted to output
voltages (3.3 V, 5 V, 12 V, -12 V) dropping out
of regulation limits.
Duration of PWOK being in the deasserted state
during an off/on cycle using AC or the PSON#
signal.
Delay from 5 VSB being in regulation to O/Ps
being in regulation at AC turn on.
Table 21: Turn On/Off Timing
1500 ms
2500 ms
18 ms
5 400 ms
50 ms
100 1000 ms
1 ms
100 ms
50 1000 ms
STATUS
Recommended
Item Description MIN MAX UNITS
T
Time all output voltages stay within regulation
vout_holdup
T
pwok_holdup
T
sb_holdup
after loss of AC.
Delay from loss of AC to deassertion of PWOK. 20 ms
Time 5VSB output voltage stays within regulation
after loss of AC.
21 ms
70 ms
Page 25 of 35
SSI
AC Input
Vout
PWOK 5VSB
PSON#
T
T
T
T
T
T
T
T
T
T
T
T
AC turn on/off cycle
PSON turn on/off cycle
EPS1U Power Supply Design Guide, V2.0
vout_holdup
sb_on_delay
T
AC_on_delay
pwok_on
pwok_holdup
sb_vout
pwok_off
Tsb_holdup
Figure 6: Turn On/Off Timing (Signal Power Supply)
pwok_low
sb_on_delay
pson_on_delay
pwok_on
pwok_off
pson_pwok
Page 26 of 35
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EPS1U Power Supply Design Guide, V2.0
7 Protection Circuits
STATUS
Required
Protection circuits inside the power supply shall cause only the power supply’s main outputs to shutdown. If the
power supply latches off due to a protection circuit tripping, an AC cycle OFF for 15 seconds and a PSON# cycle
HIGH for 1 second shall be able to reset the power supply.
7.1 Current Limit
STATUS
Required
The power supply shall have current limit to prevent the +3.3 V, +5 V, and +12 V outputs from exceeding the
values shown in Table 22. If the current limits are exceeded, the power supply shall shutdown and latch off. The
latch will be cleared by toggling the PSON# signal or by an AC power interruption. The power supply shall not be
damaged from repeated power cycling in this condition. –12 V and 5 VSB shall be protected under over current
or shorted conditions so that no damage can occur to the power supply. All outputs shall be protected so that no
damage occurs to the power supply under a shorted output condition.
Voltage Over Current Limit (Iout limit)
+3.3 V 110% minimum; 150% maximum
+5 V 110% minimum; 150% maximum
+12 V 110% minimum; 150% maximum
7.2 240VA Protection
STATUS
Recommended
System designs may require user access to energized areas of the system. In these cases the power supply may
be required to meet regulatory 240VA limits for any power rail. Since the +12V rail combined power exceeds
240VA it must be divided into separate channels to meet this requirement. Each separate rail needs to be limited
to less than 20A for each +12V rail. The separate +12V rails do not necessarily need to be independently
regulated outputs. They can share a common power conversion stage. The +12V rail is divided into two rails for
the 250W, 350W, and 400W power levels. +12V1 is dedicated for providing power to the input of the processor
voltage regulator(s). The +12V2 rail is used to power the rest of the main board +12V power needs and
peripherals devices. The +12V rail is divided into three rails for the 450W and 500W power levels. The +12V1
and +12V2 rails are dedicated for providing power to the inputs of the processor voltage regulators. The +12V3
rail is used to power the rest of the main board +12V power needs and peripheral devices.
Table 22: Over Current Protection
Page 27 of 35
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EPS1U Power Supply Design Guide, V2.0
250W – 400W 450W – 500W
Voltage Over Current Limit (Iout limit) Over Current Limit (Iout limit)
+3.3 V 110% minimum; 150% maximum 110% minimum; 150% maximum
+5 V 110% minimum; 150% maximum 110% minimum; 150% maximum
+12V1 18A minimum; 20A maximum; 22A peak1 15A minimum; 20A maximum
+12V2 18A minimum; 20A maximum 15A minimum; 20A maximum
+12V3 Not needed on the 250W to 400W power range 18A minimum; 20A maximum
1. Peak currents shall be maintained for a minimum of 500msec. The maximum duration of the peak
current exceeding the 240VA limit should be limited to meet safety regulations. A maximum duration
of 1 second is recommended. This only applies to the +12V1 output for the 250W – 400W power
range.
7.3 Over Voltage Protection
STATUS
Required
The power supply over voltage protection shall be locally sensed. The power supply shall shutdown and latch off
after an over voltage condition occurs. This latch shall be cleared by toggling the PSON# signal or by an AC
power interruption. Table 24 contains the over voltage limits. The values are measured at the output of the
power supply’s connectors. The voltage shall never exceed the maximum levels when measured at the power
pins of the power supply connector during any single point of fail. The voltage shall never trip any lower than the
minimum levels when measured at the power pins of the power supply connector.
Output Voltage MIN (V) MAX (V)
+3.3 V 3.9 4.5
+5 V 5.7 6.5
+12 V1, 2 13.3 14.5
-12 V -13.3 -14.5
+5 VSB 5.7 6.5
7.4 Over Temperature Protection
STATUS
Recommended
The power supply will be protected against over temperature conditions caused by loss of fan cooling or
excessive ambient temperature. In an OTP condition the PSU will shutdown. When the power supply
temperature drops to within specified limits, the power supply shall restore power automatically. The OTP circuit
must have built in hysteresis such that the power supply will not oscillate on and off due to temperature recovering
condition. The OTP trip level shall have a minimum of 4 °C of ambient temperature hysteresis.
Table 23: Over Current Protection
Table 24: Over Voltage Limits
Page 28 of 35
SSI
PS must
PS must
EPS1U Power Supply Design Guide, V2.0
8 Control and Indicator Functions
The following sections define the input and output signals from the power supply.
Signals that can be defined as low true use the following convention:
signal# = low true
8.1 PSON#
STATUS
Required
The PSON# signal is required to remotely turn on/off the power supply. PSON# is an active low signal that turns
on the +3.3 V, +5 V, +12 V, and –12 V power rails. When this signal is not pulled low by the system, or left open,
the outputs (except the +5 VSB and Vbias) turn off. This signal is pulled to a standby voltage by a pull-up resistor
internal to the power supply. Refer to Figure 6 for the timing diagram.
Signal Type
PSON# = Low
PSON# = Open or High
Logic level low (power supply ON)
Logic level high (power supply OFF)
Source current, Vpson = low
Power up delay: T
PWOK delay: T
pson_pwok
Table 25: PSON# Signal Characteristic
pson_on_delay
Disabled
Hysteresis ≥ 0.3V and/or other de-bounce method
Enabled
0V
Figure 7: PSON# Signal Characteristics
Accepts an open collector/drain input from the system.
Pull-up to VSB located in power supply.
MIN MAX
0 V 1.0 V
2.0 V 5.25 V
5 ms 400 ms
≤ 1.0 V
be
enabled
1.0V 2.0V
4 mA
50 ms
≥ 2.0 V
be
disabled
ON
OFF
5.25V
Page 29 of 35
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EPS1U Power Supply Design Guide, V2.0
8.2 PWOK (Power OK)
STATUS
Required
PWOK is a power OK signal and will be pulled HIGH by the power supply to indicate that all the outputs are within
the regulation limits of the power supply. When any output voltage falls below regulation limits or when AC power
has been removed for a time sufficiently long so that power supply operation is no longer guaranteed, PWOK will
be de-asserted to a LOW state. See Figure 6 for a representation of the timing characteristics of PWOK. The
start of the PWOK delay time shall be inhibited as long as any power supply output is in current limit.
Signal Type
PWOK = High
PWOK = Low
Logic level low, Isink = 4mA
Logic level high, Isource = 200µA
PWOK delay: T
PWOK rise and fall time
Power down delay: T
Table 26: PWOK Signal Characteristics
pwok_on
pwok_off
+5V TTL Compatible output signal
Power OK
Power not OK
MIN MAX
0.4 V
2.4 V 5.25 V
200 ms 1000 ms
1 ms
100 µs
Page 30 of 35
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EPS1U Power Supply Design Guide, V2.0
8.3 ACWarning
STATUS
Optional
This is an output signal from the power supply, which provides a warning to the system that the power supply has
lost its AC input. This signal also provides a signal to synchronize the turn on of multiple power supplies. At turn
on, this signal is pulled LOW when the supply’s internal bulk voltage has reached a level that allows it to turn on.
At turn off ACWarning goes HIGH when the internal bulk voltage drops low enough. The characteristics of the
ACWarning signal are shown in Table 27: ACWarning Signal Characteristics. Refer to Figure 6 for timing
diagram.
Signal Type
ACWarning = Low Input voltage within operating range and power
ACWarning = High Input voltage is less than the operating range and the
MIN MAX
Logic level low, Isink = 4mA 0V 0.4V
Logic level high, Isource = 200µA
ACWarning Delay: T
ACWarning rise and fall time
Power supply turn on voltage 75VAC 85VAC
Table 27: ACWarning Signal Characteristics
acwarning_delay
+5V TTL Compatible output signal
supply is ready to turn on.
power supply is turning off.
8msec
2.4 V 5.25V
100µsec
Page 31 of 35
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EPS1U Power Supply Design Guide, V2.0
8.4 Field Replacement Unit (FRU) Signals
STATUS
Optional
Two pins will be allocated for the FRU information on the power supply connector. One pin is the Serial Clock
(SCL). The second pin is used for Serial Data (SDA). Both pins are bi-directional and are used to form a serial
bus. The FRU circuits inside the power supply must be powered off of 5 VSB output and grounded to ReturnS
(remote sense return). The Write Control (or Write protect) pin should be tied to ReturnS inside the power supply
so that information can be written to the EEPROM.
8.4.1 FRU Data
FRU data shall be stored starting in address location 8000h through 80FFh. The FRU data format shall be
compliant with the IPMI specifications. The current version of these specifications is available at
http:\\developer.intel.com/design/servers/ipmi/spec.htm.
8.4.2 FRU Data Format
The information to be contained in the FRU device is shown in the following table.
Area Type Description
Common Header As defined by the FRU document
Internal Use Area Not required, do not reserve
Chassis Info Area Not applicable, do not reserve
Board Info Area Not applicable, do not reserve
Table 28: FRU Device Information
8.4.2.1 Product Info Area
As defined by the IPMI FRU document. Product information shall be defined as follows:
Field Name Field Description
Manufacturer Name {Formal name of manufacturer}
Product Name {Manufacturer’s model number}
Product part/model
number
Product Version Customer current revision
Product Serial Number {Defined at time of manufacture}
Asset Tag {Not used, code is zero length byte}
FRU File ID {Not required}
PAD Bytes {Added as necessary to allow for 8-byte offset to next area}
Table 29: FRU Device Product Information Area
Customer part number
Page 32 of 35
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EPS1U Power Supply Design Guide, V2.0
8.4.2.2 MultiRecord Area
As defined by the IPMI FRU document. The following record types shall be used on this power supply:
• Power Supply Information (Record Type 0x00)
• DC Output (Record Type 0x01)
• No other record types are required for the power supply.
MultiRecord information shall be defined as follows:
Field Name (PS Info) Field Information Definition
Overall Capacity (W) 350 {Low power versions would be 250 or 125}
Peak VA 400 {Low power versions would be 300 or 161}
Inrush current (A) 30
Inrush interval (ms) 5
Low end input voltage
range 1
High end input voltage
range 1
Low end input voltage
range 2
High end input voltage
range 2
A/C dropout tol. (ms) 20
Binary flags Set for: Not Hot Swap support, Auto-switch, and PFC
Peak Wattage Set for: 12 s, 400 W {Low power versions would be 300W or 161W}
Combined wattage Set for 5 V & 3.3 V combined wattage of 113 W {Low power versions would be 113W
Predictive fail tach
support
Field Name (Output) Field Description: Six outputs are to be defined from #1 to #6, as follows: +3.3 V, +5
Output Information Set for: Standby on +5 VSB, No Standby on all others.
All other output fields Format per IPMI specification, using parameters in the EPS1U specification.
Table 30: FRU Device MultiRecord Area
90
140
180
264
or 80}
Not supported, 00h value
V, +12 V1, +12V2, -12 V, and +5 VSB.
Page 33 of 35
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EPS1U Power Supply Design Guide, V2.0
8.5 LED Indicator
STATUS
Required
There will be a single GREEN LED to indicate power supply status. When AC is applied to the PSU and standby
voltages are available the LED shall BLINK GREEN. The LED shall turn ON GREEN to indicate that all the power
outputs are available. Refer to Table 31 for conditions of the LED.
Power Supply Condition Power Supply LED
No AC power to PSU or PSU failure OFF
AC present / Only Standby Output ON BLINK GREEN
Power supply DC outputs ON and OK GREEN
The LED shall be visible on the power supply’s exterior face. The LED location shall meet ESD requirements.
LED shall be securely mounted in such a way that incidental pressure on the LED shall not cause it to become
displaced.
9 MTBF
STATUS
Recommended
The power supply shall have a minimum MTBF at continuous operation of 1) 100,000 hours at 100% load and
45° C, as calculated by Bellcore RPP, or 2) 250,000 hours demonstrated at 100% load and 45° C.
Table 31: LED Indicators
Page 34 of 35
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EPS1U Power Supply Design Guide, V2.0
10 Agency Requirements
STATUS
Recommended
The power supply must comply with all regulatory requirements for its intended geographical market. Depending
on the chosen market, regulatory requirements may vary. Although a power supply can be designed for
worldwide compliance, there may be cost factors that drive different versions of supplies for different
geographically targeted markets.
This specification requires that the power supply meet all regulatory requirements for the intended market at the
time of manufacturing. Typically this includes:
• UL
• CSA
• A Nordic CENELEC
• TUV
• VDE
• CISPR Class B
• FCC Class B
The power supply, when installed in the system, shall meet immunity requirements specified in EN55024.
Specific tests are to be EN61000-4-2 ,-3, -4, -5, -6, -8, and -11. The power supply must maintain normal
performance within specified limits. This testing must be completed by the system EMI engineer. Conformance
must be designated with the European Union CE Marking. Specific immunity level requirements are left to
customer requirements.
Page 35 of 35
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