Enhance LFX12V Version 1.0 Power Supply Design Guide

LFX12V Power Supply Design Guide

Lowprofile Form Factor with 12-Volt Connector

LFX12V

Lowprofile Form Factor with 12-Volt Connector

Power Supply Design Guide

Version 1.0

Revision History

Version Release Date Notes

1.0 April, 2004

• First public release.

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LFX12V Power Supply Design Guide

Lowprofile Form Factor with 12-Volt Connector

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Contents

1 Introduction .................................................................................................... 6

1.1 Scope 6

1.2 Terminology ...................................................................................................................6

2 Electrical ......................................................................................................... 7

2.1 AC Input 7

2.1.1 Input Over Current Protection.......................................................................... 8

2.1.2 Inrush Current Limiting .................................................................................... 8

2.1.3 Input Under Voltage......................................................................................... 8

2.1.4 Regulatory ....................................................................................................... 8

2.1.5 Catastrophic Failure Protection ....................................................................... 9

2.2 DC Output .................................................................................................................... 10

2.2.1 DC Voltage Regulation .................................................................................. 10

2.2.2 Remote Sensing ............................................................................................ 10

2.2.3 Typical Power Distribution ............................................................................. 11

2.2.4 Power Limit / Hazardous Energy Levels........................................................ 13

2.2.5 Efficiency General .........................................................................................13

2.2.6 Output Ripple/Noise ......................................................................................14

2.2.7 Output Transient Response........................................................................... 16

2.2.8 Capacitive Load.............................................................................................19

2.2.9 Closed-loop Stability......................................................................................19

2.2.10 +5 VDC / +3.3 VDC Power Sequencing ........................................................ 19

2.2.11 Voltage Hold-up Time.................................................................................... 19

2.3 Timing / Housekeeping / Control..................................................................................20

2.3.1 PWR_OK ....................................................................................................... 20

2.3.2 PS_ON# ........................................................................................................21

2.3.3 +5 VSB .......................................................................................................... 22

2.3.4 Power-on Time .............................................................................................. 22

2.3.5 Rise Time ......................................................................................................22

2.3.6 Overshoot at Turn-on / Turn-off..................................................................... 22

2.3.7 Reset after Shutdown .................................................................................... 23

2.3.8 +5 VSB at AC Power-down ...........................................................................23

2.4 Output Protection ......................................................................................................... 23

2.4.1 Over Voltage Protection ................................................................................23

2.4.2 Short-circuit Protection .................................................................................. 23

2.4.3 No-load Operation ......................................................................................... 24

2.4.4 Over Current Protection................................................................................. 24

2.4.5 Over-temperature Protection ......................................................................... 24

2.4.6 Output Bypass ............................................................................................... 24

3 Mechanical.................................................................................................... 25

3.1 Labeling /Marking.........................................................................................................25

3.2 Physical Dimensions .................................................................................................... 25

3.2 AC Connector............................................................................................................... 29

3.3 DC Connectors............................................................................................................. 29

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3.3.1 Main Power Connector .................................................................................. 31

3.3.2 Peripheral Connector(s) ................................................................................31

3.3.3 Floppy Drive Connector................................................................................. 32

+12 V Power Connector ............................................................................................... 32

3.3.4 Serial ATA Power Connector......................................................................... 32

4 Thermal Requirements ................................................................................ 33

4.1 Fan and Venting...........................................................................................................33

4.2 Airflow and Acoustics ................................................................................................... 33

4.3 Airflow / Fan ................................................................................................................. 35

5 Environmental .............................................................................................. 37

5.1 Temperature................................................................................................................. 37

5.2 Thermal Shock (Shipping)............................................................................................ 37

5.3 Relative Humidity ......................................................................................................... 37

5.4 Altitude Requirement.................................................................................................... 37

5.5 Mechanical Shock ........................................................................................................ 37

5.6 Random Vibration ........................................................................................................38

5.7 Acoustics......................................................................................................................38

5.8 Ecological Requirements .............................................................................................38

6 Safety............................................................................................................. 39

6.1 North America .............................................................................................................. 39

6.2 International .................................................................................................................40

7 System Cooling Considerations................................................................. 41

8 Reliability ...................................................................................................... 42

9 Applicable Documents ................................................................................ 43

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Figures

Figure 1: Cross Loading Graph for 180W configuration ............................................................11

Figure 2. Cross Loading Graph for 200W Configuration............................................................ 12

Figure 3. Differential Noise Test Setup ...................................................................................... 16

Figure 4. Power Supply Timing..................................................................................................20

Figure 5. PS_ON# Signal Characteristics.................................................................................. 21

Figure 6. Mechanical Outline ..................................................................................................... 26

Figure 7. Mechanical Details...................................................................................................... 27

Figure 8. PSU Slot Feature Detail..............................................................................................28

Figure 9. Recommended Chassis Tab Feature ......................................................................... 29

Figure 10. Connectors (Pin-side view, not to scale) ..................................................................30

Figure 11. Serial ATA Connector ................................................................................................ 32

Figure 12. AMCA* Standard 210 ...............................................................................................35

Tables

Table 1. AC Input Line Requirements.......................................................................................... 8

Table 2. DC Output Voltage Regulation..................................................................................... 10

Table 3. Typical Power Distribution for 180 W Configurations................................................... 11

Table 4. Typical Power Distribution for 200 W Configurations................................................... 12

Table 5. Efficiency Vs Load ......................................................................................................13

Table 6. Loading Tables for Efficiency Measurements ............................................................. 13

Table 7. Energy Star* Input Power Consumption....................................................................... 14

Table 8. DC Output Noise/Ripple............................................................................................... 16

Table 9. DC Output Transient Step Sizes.................................................................................. 18

Table 10. Output Capacitive Loads............................................................................................. 19

Table 11. PWR_OK Signal Characteristics................................................................................. 20

Table 12. PS_ON# Signal Characteristics .................................................................................. 21

Table 13. Over Voltage Protection.............................................................................................. 23

Table 14. Airflow and Acoustic Recommendations..................................................................... 34

Table 15. Loading for Acoustic Test for 180 Watts ..................................................................... 34

Table 16. Loading for Acoustic Test for 200 Watts ..................................................................... 34

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1 Introduction

1.1 Scope

This document provides design suggestions for power supply(s) that support Balanced
Technology Extended (BTX) form factor systems. The power supply(s) are primarily
intended for use with ultra small form factor system designs (6 –9 liters in total system
volume). It should not be inferred that all power supplies built to support Balanced
Technology Extended based systems must conform exactly to the content of this document,
though there are key parameters that define mechanical fit across a common set of
platforms. Since power supply needs vary depending on system configuration, the design
specifics described are not intended to support all possible systems.

1.2 Terminology

The following terms are used in this document:

Term Description

Required

Recommended

Optional

B

A

CFM

Monotonically

The status given to items within this design guide, which are required
to meet design guide and a large majority of system applications.

The status given to items within this design guide, which are not
required to meet design guide, however, are required by many system
applications.

The status given to items within this design guide, which are not
required to meet design guide, however, some system applications
may optionally use these features.

Declared sound power, LwAd. The declared sound power level shall
be measured according to ISO* 7779 for the power supply and
reported according to ISO 9296.

Cubic Feet per Minute (airflow).

A waveform changes from one level to another in a steady fashion,
without oscillation.

Noise

6

The periodic or random signals over frequency band of 0 Hz to 20
MHz.

Lowprofile Form Factor with 12-Volt Connector

Term Description

LFX12V Power Supply Design Guide

Overcurrent

PFC

Ripple

Rise Time

Surge

VSB or Standby
Voltage

MTBF

PWR_OK

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.

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 rises above nominal voltage.

An output voltage that is present whenever AC power is applied to the
AC inputs of the supply.

Mean time between failure.

PWR_OK is a “power good” signal used by the system power supply
to indicate that the +5VDC, +3.3 VDC and +12VDC outputs are above
the undervoltage thresholds of the power supply.

2 Electrical

The following electrical requirements are required and must be met over the
environmental ranges as defined in Section 5 (unless otherwise noted).

2.1 AC Input

Table 1, lists AC input voltage and frequency requirements for continuous operation.
The power supply shall be capable of supplying full-rated output power over the
voltage ranges shown in
environment may be either switch-selectable or auto-ranging. The power supply
shall automatically recover from AC power loss. The power supply must be able to
start up under peak loading at 90 VAC.

Table 1. The correct input range for use in a given

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Table 1. AC Input Line Requirements

Parameter Minimum Nominal

Vin (115 VAC) 90 115 135 VAC

Vin (230 VAC) 180 230 265 VAC

Vin Frequency 47 -- 63 Hz

Iin (115 VAC) 6 A rms

Iin (230 VAC) 3 A rms

(1)

Note:

Nominal voltages for test purposes are considered to be within ±1.0 V of nominal.

(1)

Maximum Unit

2.1.1 Input Over Current Protection

The power supply is required to incorporate primary fusing 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.1

rms

rms

2.1.2 Inrush Current Limiting

Maximum inrush current from power-on (with power-on at any point on the AC sine)
and including, but not limited to, three line cycles, shall be limited to a level below
the surge rating of the input line cord, AC switch if present, bridge rectifier, fuse, and
EMI filter components. Repetitive ON/OFF cycling of the AC input voltage should
not damage the power supply or cause the input fuse to blow.

2.1.3 Input Under Voltage

The power supply is required to contain protection circuitry such that the application
of an input voltage below the minimum specified in Section 2.1, Table 1, shall not
cause damage to the power supply.

2.1.4 Regulatory

The power supply is required to be tested and comply with the most current version
of the following regulatory specification requirements and/or standards

2.1.4.1 PRODUCT SAFETY

UL* 60950, 3

EN*60 950, 3rd Edition

rd

Edition –CAN/CSA-C22.2-60950-00,

IEC*60 950, 3rd Edition (CB Report to include all national deviations)

1

For Denmark and Switzerland international safety requirements, if the internal over current protective devices exceed 8A for

Denmark and 10A for Switzerland, then the power supply must pass international safety testing to EN 60950 using a
maximum 16A over-current protected branch circuit, and this 16A (time delay fuse) branch circuit protector must not open
during power supply abnormal operation (output short circuit and component fault) testing.

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EU* Low Voltage Directive (73/23/EEC) (CE Compliance)

GB4943-90 CCIB* (China)

2.1.4.2 ELECTROMAGNETIC CAMPATIBILITY

FCC*, Class B, Part 15 (Radiated & Conducted Emissions)

CISPR* 22 / EN55022, 3rd Edition (Radiated & Conducted Emissions)

EN55024 (ITE Specific Immunity)

EN 61000-4-2 – Electrostatic Discharge

EN 61000-4-3– Radiated RFI Immunity

EN 61000-4-4– Electrical Fast Transients.

EN 61000-4-5 – Electrical Surge

EN 61000-4-6 – RF Conducted

EN 61000-4-8 – Power Frequency Magnetic Fields

EN 61000-4-11 – Voltage Dips, Short Interrupts and Fluctuations

EN61000-3-2 (Harmonics)

EN61000-3-3 (Voltage Flicker)

EU EMC Directive ((8/9/336/EEC) (CE Compliance)

2.1.4.3 Other Certifications and/or Declarations

GB925 (China/CCC*), CNS13438 (Taiwan/BSMI*), AS/NZ3548 (Australia/C-tick*
based on CISPR22)

2.1.5 Catastrophic Failure Protection

Should a component failure occur, the power supply should not exhibit any of the
following:

• Flame

• Excessive smoke

• Charred PCB

• Fused PCB conductor

• Startling noise

• Emission of molten material

• Earth ground fault (short circuit to ground or chassis enclosure)

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2.2 DC Output

2.2.1 DC Voltage Regulation

The DC output voltages are required to remain within the regulation ranges shown in
Table 2, when measured at the load end of the output connectors under all line, load,
and environmental conditions specified in Section 5.

Table 2. DC Output Voltage Regulation

Output Range Min. Nom. Max. Unit

(1)

±5% +11.40 +12.00 +12.60 Volts

+5VDC ±5% +4.75 +5.00 +5.25 Volts

(2)

±5% +3.14 +3.30 +3.47 Volts

+5VSB ±5% +4.75 +5.00 +5.25 Volts

Note:.

(2)

+12VDC

+3.3VDC

-12VDC ±10% -10.80 -12.00 -13.20 Volts

(1)

At +12 VDC peak loading, regulation at the +12 VDC output can go to ± 10%.

Voltage tolerance is required at main connector and S-ATA connector (if used).

2.2.2 Remote Sensing

The +3.3 VDC output should have provisions for remote sensing to compensate for
excessive cable drops. The default sense should be connected to pin 13 of the main
power connector. The power supply should draw no more than 10 mA through the
remote sense line to keep DC offset voltages to a minimum.

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2.2.3 Typical Power Distribution

DC output power requirements and distributions will vary based on specific system
options and implementation.

Significant dependencies include the quantity and types of processors, memory, add­in card slots, and peripheral bays, as well as support for advanced graphics or other
features. Table 3 through Table 4 and Figure 1 through Figure 2 shows the power
distribution and cross loading tables for power supplies in the range of 180 W to

200W. These are recommendations but it is ultimately the responsibility of the
designer to define a power budget for a given target product and market.

Table 3. Typical Power Distribution for 180 W Configurations

Output

+12 VDC 1.0 13.0 14.0

+5 VDC 0.3 8.0

+3.3 VDC 0.5 5.0

-12 VDC 0 0.3

+5 VSB 0 2.0 2.5

Note: Total combined output of 3.3 V and 5 V is ≤ 50 W

Minimum Current
(amps)

Rated Current
(amps)

Peak Current
(amps)

Figure 1: Cross Loading Graph for 180W configuration

180W Cross Regulation

(5V rail + 3.3V rail vs. 12V)

60

50

40

30

20

Combined Power
(5V rail + 3.3V rail)

10

5V + 3.3V power (watts)

0

050100150200

12V power (watts)

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Table 4. Typical Power Distribution for 200 W Configurations

Output

+12 VDC 1.0 13.5 14.5

+5 VDC 0.3 9.0

+3.3 VDC 0.5 6.0

-12 VDC 0 0.3

+5 VSB 0 2.0 2.5

Note: Total combined output of 3.3 V and 5 V is ≤ 60 W

Minimum Current
(amps)

Rated Current
(amps)

Peak Current
(amps)

Figure 2. Cross Loading Graph for 200W Configuration

200W Cross Regulation

(5V rail + 3.3V rail vs. 12V)

70

60

50

40

30

20

Combined Power
(5V rail + 3.3V rail)

10

5V + 3.3V power (watts)

0

0 50 100 150 200

12V p o wer (watts)

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2.2.4 Power Limit / Hazardous Energy Levels

Under normal or overload conditions, it is required that no output shall continuously
provide more than 240 VA under any conditions of load including output short

circuit, per the requirement of UL 1950/CSA 950 / EN 60950/IEC 950 specification.

2.2.5 Efficiency General

The power supply should have a required minimum efficiency as stated in Table 5
and when cost effective provide the recommended efficiency in Table 5. The
efficiency of the power supply should be tested at nominal input voltage of 115VAC
input and 230VAC input, under the load conditions defined in Table 5, and under the
temperature and operating conditions defined in Section 3. The loading condition for
testing efficiency shown in Table 5 represents a fully loaded system, a 50% loaded
system (typical load), and a 20% loaded (light load) system.

Table 5. Efficiency Vs Load

Loading

Required: Minimum Efficiency

Recommended: Minimum Efficiency

Full load Typical load Light load

70% 70% 60%

75% 80% 67%

Table 6. Loading Tables for Efficiency Measurements

180W (loading shown in Amps)

Loading +12V +5V +3.3V -12V +5Vsb

Full 11.0 7.0 4.0 0.2 0.5

Typical 6.0 3.0 3.0 0.1 0.5

Light 2.8 0.3 0.5 0 0.1

200W (loading shown in Amps)

Loading +12V +5V +3.3V -12V +5Vsb

Full 11.5 8.0 6.0 0.2 1.0

Typical 7.0 3.0 4.0 0.1 1.0

Light 3.0 0.4 0.5 0 0.5

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2.2.5.1 Energy Star*

The “Energy Star” efficiency requirements of the power supply depend on the
intended system configuration. In the low power / sleep state (S1 or S3) the system
should consume power in accordance with the values listed in Table 7.

Table 7. Energy Star Input Power Consumption

Maximum Continuous Power Rating of

Power Supply

< 200 W < 15 W

> 200 W < 300 W < 20 W

> 300 W < 350 W < 25 W

> 350 W < 400 W < 30 W

> 400 W 10% of the maximum continuous output rating

Note: To help meet the “Energy Star” system requirements, it is recommended that the power supply have ≥ 50%
efficiency at light load and in standby mode.

RMS Watts from the AC Line in Sleep/low-Power

Mode

2.2.5.2 Other Low Power System Requirements

To help meet the Blue Angel* system requirements, RAL-UZ 78, US
Presidential executive order 13221, future EPA requirements, and other low
Power system demands, it recommended that the +5 VSB standby supply
efficiency should be as high as possible. Standby efficiency is measured with
the main outputs off (PS_ON# high state). Standby efficiency should be
greater than 50% with a load of 100mA.

2.2.6 Output Ripple/Noise

The output ripple/noise requirements listed in

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Table 8 should be met throughout the load ranges specified in Section 2.2.3 and
under all input voltage conditions as specified in 2.1, Table 1.

Ripple and noise are defined as periodic or random signals over a frequency band of
10 Hz to 20 MHz. Measurements shall be made with an oscilloscope with 20 MHz of
bandwidth. Outputs should be bypassed at the connector with a 0.1µF ceramic disk
capacitor and a 10µF electrolytic capacitor to simulate system loading. See Figure 3.

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LFX12V Power Supply Design Guide

A

A

A

Lowprofile Form Factor with 12-Volt Connector

Table 8. DC Output Noise/Ripple

Output Maximum Ripple and Noise

+12 VDC 120

+5 VDC 50

+3.3 VDC 50

-12 VDC 120

+5 VSB 50

(mVpp)

Power Supply

C Hot

C Neutral

C Ground

General Notes:

1. Lo ad the outp ut with its minimum load
curre nt.

2. Connect the probes as shown.

3. Repeat the measurement with maximum
load on th e outp ut.

Filter Note:

0.1uf – Kemet*, C1206C104K5RAC or equivalent
10uf - United Chemi-con*, 293D106X0025D2T or
equivalen t

Figure 3. Differential Noise Test Setup

V out

V return

10uf

0.1uf

Scope Note:

Use Tek tronix* T DS4 60 O scillos cope or
equivalent and a P6046 probe or equivalent.

Load

Load must be
isola ted from the
ground of the
power supply.

Scope

2.2.7 Output Transient Response

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Table 9 summarizes the expected output transient step sizes for each output. The
transient load slew rate is = 1.0 A/µs.

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Table 9. DC Output Transient Step Sizes

Output

Maximum Step Size

(% of rated output amps)

Maximum Step Size

(amps)

+12 VDC 50%

+5 VDC 30%

+3.3 VDC 30%

-12 VDC 0.1 A

+5 VSB 0.5 A

Note: For example, for a rated +5 VDC output of 14 A, the transient step would be 30% × 14 A = 4.2 A

Output voltages should remain within the regulation limits of Table 2, Section 2.2.1, for instantaneous
changes in load as specified in

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Table 9 and for the following conditions:

• Simultaneous load steps on the +12 VDC, +5 VDC, and +3.3 VDC outputs (all steps occurring in
the same direction)

• Load-changing repetition rate of 50 Hz to 10 kHz

• AC input range per Section 2.1 and capacitive loading per Table 10

2.2.8 Capacitive Load

The power supply should be able to power up and operate with the regulation limits
defined in Table 2, Section 2.2.1, with the following capacitances simultaneously
present on the DC outputs.

Table 10. Output Capacitive Loads

Output Capacitive Load

(µF)

+12 VDC 3,000

+5 VDC 5,000

+3.3 VDC 3,000

-12 VDC 350

+5 VSB 350

2.2.9 Closed-loop Stability

The power supply is required to be unconditionally stable under all line/load/transient
load conditions including capacitive loads specified in Section 2.2.8. A minimum of
45 degrees phase margin and 10 dB gain margin is recommended at both the
maximum and minimum loads.

2.2.10 +5 VDC / +3.3 VDC Power Sequencing

The +12 VDC and +5 VDC output levels must be equal to or greater than the +3.3
VDC output at all times during power-up and normal operation. The time between
the +12 VDC or +5 VDC output reaching its minimum in-regulation level and +3.3
VDC reaching its minimum in-regulation level must be ≤ 20 ms.

2.2.11 Voltage Hold-up Time

The power supply should maintain output regulations per Section 2.2.1 despite a loss
of input power at the low-end nominal range—115 VAC / 57 Hz or 230 VAC / 47 Hz

- at maximum continuous output load as applicable for a minimum of 17 ms.

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2.3 Timing / Housekeeping / Control

VAC

PS_ON#

~

~

+12VDC

+5VDC

+3.3VDC

O/P's

}

PWR_OK

95%

10%

T2

T3

T4

~

~

T5T1

T6

PWR_OK Sense Level = 95% of nominal

Figure 4. Power Supply Timing

Notes: T1 is defined in Section 2.3.4. , T2 in Section 2.3.5. ,T3, T4, T5, and T6 are defined in Table 11.

2.3.1 PWR_OK

PWR_OK is a “power good” signal. This signal should be asserted high by the
power supply to indicate that the +12 VDC, +5 VDC, and +3.3 VDC outputs are
above the under voltage thresholds listed in Table 2 in Section 2.2.1 and that
sufficient mains energy is stored by the converter to guarantee continuous power
operation within specification for at least the duration specified in Section 2.2.11,
“Voltage Hold-up Time.” Conversely, PWR_OK should be de-asserted to a low state
when any of the +12 VDC, +5 VDC, or +3.3 VDC output voltages falls below its
under voltage threshold, or when mains power has been removed for a time
sufficiently long such that power supply operation cannot be guaranteed beyond the
power-down warning time. The electrical and timing characteristics of the PWR_OK
signal are given in Table 11 and in Figure 4

Table 11. PWR_OK Signal Characteristics

Signal Type +5 V TTL compatible

Logic level low < 0.4 V while sinking 4 mA

Logic level high Between 2.4 V and 5 V output while sourcing 200 µA

High-state output impedance

PWR_OK delay 100 ms < T3 < 500 ms

PWR_OK rise time

AC loss to PWR_OK hold-up time

Power-down warning

1 kΩ from output to common

T4 ≤ 10 ms

T

T

.

≥ 16 ms

5

≥ 1 ms

6

timing_3_5_12b

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2.3.2 PS_ON#

PS_ON# is an active-low, TTL-compatible signal that allows a motherboard to
remotely control the power supply in conjunction with features such as soft on/off,

Wake on LAN*, or wake-on-modem. When PS_ON# is pulled to TTL low, the
power supply should turn on the four main DC output rails: +12 VDC, +5 VDC, +3.3
VDC, and -12 VDC. When PS_ON# is pulled to TTL high or open-circuited, the DC
output rails should not deliver current and should be held at zero potential with
respect to ground. PS_ON# has no effect on the +5 VSB output, which is always
enabled whenever the AC power is present. Table 12 lists PS_ON# signal
characteristics.

The power supply shall provide an internal pull-up to TTL high. The power supply
shall also provide de-bounce circuitry on PS_ON# to prevent it from oscillating
on/off at startup when activated by a mechanical switch. The DC output enable
circuitry must be SELV-compliant.

The power supply shall not latch into a shutdown state when PS_ON# is driven active
by pulses between 10ms to 100ms during the decay of the power rails.

Table 12. PS_ON# Signal Characteristics

Parameter Minimum Maximum

VIL, Input Low Voltage 0.0 V 0.8 V

IIL, Input Low Current (Vin = 0.4 V) -1.6 mA

VIH, Input High Voltage (Iin = -200 µA) 2.0 V

VIH open circuit, Iin = 0 5.25 V

≤

0.8 V
PS is

enabled

Hysteresis ≥ 0.3 V

0.8 2.0

PS_ON# Voltage

≥

2.0 V
PS is

disabled

5.25 = Maximum Open­Circuit Voltage

Disable

Enable

Figure 5. PS_ON# Signal Characteristics

2.3.3 +5 VSB

+5 VSB is a standby supply output that is active whenever the AC power is present.
This output provides a power source for circuits that must remain operational when

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the five main DC output rails are in a disabled state. Example uses include soft
power control, Wake on LAN, wake-on-modem, intrusion detection, or suspend state
activities.

The +5 VSB output should be capable of delivering a minimum of 2.0 A. at +5 V ±
5% to external circuits. The power supply is required to provide the required power
during a "wake up" event. If an external USB device generates the event, there may
be peak currents as high as 2.5 A., lasting no more than 500 ms.

Over current protection is required on the +5 VSB output regardless of the output
current rating. This ensures the power supply will not be damaged if external circuits
draw more current than the supply can provide.

2.3.4 Power-on Time

The power-on time is defined as the time from when PS_ON# is pulled low to when
the +12 VDC, +5 VDC, and +3.3 VDC outputs are within the regulation ranges
specified in Section 2.2.1. The power-on time shall be less than 500 ms (T1 < 500
ms).

+5 VSB shall have a power-on time of two seconds maximum after application of

valid AC voltages.

2.3.5 Rise Time

The output voltages shall rise from ≤10% of nominal to within the regulation ranges
specified in Section 2.2.1 within 0.2 ms to 20 ms (0.2 ms ≤ T2 ≤ 20 ms).

There must be a smooth and continuous ramp of each DC output voltage from 10% to
90% of its final set point within the regulation band, while loaded as specified in

2.2.3 .

The smooth turn-on requires that, during the 10% to 90% portion of the rise time, the
slope of the turn-on waveform must be positive and have a value of between 0 V/ms
and [V

, nominal / 0.1] V/ms. Also, for any 5 ms segment of the 10% to 90% rise

out

time waveform, a straight line drawn between the end points of the waveform
segment must have a slope

≥ [V

, nominal / 20] V/ms.

out

2.3.6 Overshoot at Turn-on / Turn-off

The output voltage overshoot upon the application or removal of the input voltage, or
the assertion/de-assertion of PS_ON#, under the conditions specified in Section 2.2,
shall be less than 10% above the nominal voltage. No voltage of opposite polarity
shall be present on any output during turn-on or turn-off.

2.3.7 Reset after Shutdown

If the power supply latches into a shutdown state because of a fault condition on its
outputs, the power supply shall return to normal operation only after the fault has

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been removed and the PS_ON# has been cycled OFF/ON with a minimum OFF time
of one second.

2.3.8 +5 VSB at AC Power-down

After AC power is removed, the +5 VSB standby voltage output should remain at its
steady state value for the minimum hold-up time specified in Section 2.2.11 until the
output begins to decrease in voltage. The decrease shall be monotonic in nature,
dropping to 0.0 V. There shall be no other disturbances of this voltage at or
following removal of AC power.

2.4 Output Protection

2.4.1 Over Voltage Protection

The over voltage sense circuitry and reference shall reside in packages that are
separate and distinct from the regulator control circuitry and reference. No single
point fault shall be able to cause a sustained over voltage condition on any or all
outputs. The supply shall provide latch-mode over voltage protection as defined in
Table 13.

Table 13. Over Voltage Protection

Output Minimum Nominal Maximum Unit

+12 VDC 13.4 15.0 15.6 Volts

+5 VDC 5.74 6.3 7.0 Volts

+3.3 VDC 3.76 4.2 4.3 Volts

2.4.2 Short-circuit Protection

An output short circuit is defined as any output impedance of less than 0.1 ohms. The
power supply shall shut down and latch off for shorting the +3.3 VDC, +5 VDC, or
+12 VDC rails to return or any other rail. Shorts between main output rails and +5
VSB shall not cause any damage to the power supply. The power supply shall either
shut down and latch off or fold back for shorting the negative rails. +5 VSB must be
capable of being shorted indefinitely, but when the short is removed, the power
supply shall recover automatically or by cycling PS_ON#. The power supply shall be
capable of withstanding a continuous short circuit to the output without damage or
overstress to the unit (for example, to components, PCB traces, and connectors) under
the input conditions specified in Section 2.1

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2.4.3 No-load Operation

No damage or hazardous condition should occur with all the DC output connectors
disconnected from the load. The power supply may latch into the shutdown state.

2.4.4 Over Current Protection

Overload currents applied to each tested output rail cause the output to trip before
reaching or exceeding 240 VA. For testing purposes, the overloaded currents should
be ramped at a minimum rate of 10 A/s starting from full load.

2.4.5 Over-temperature Protection

As an option, it is recommended that the power supply may include an over­temperature protection sensor, which can trip and shut down the power supply at a
preset temperature point. Such an overheated condition is typically the result of
internal current overloading or a cooling fan failure. If the protection circuit is non­latching, then it should have hysteresis built in to avoid intermittent tripping.

2.4.6 Output Bypass

The output return may be connected to the power supply chassis, and will be
connected to the system chassis by the system components.

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3 Mechanical

3.1 Labeling /Marking

The following is a non-inclusive list of suggested markings for each power supply
unit. Product regulation stipulations for sale into various geographies may impose
additional labeling requirements.

Manufacturer information: manufacturer's name, part number and lot date code, etc.,
in human-readable text and/or bar code formats

Nominal AC input operating voltages (see Table 1) and current rating certified by all
applicable safety agencies

DC output voltages and current ratings

Access warning text (“Do not remove this cover. Trained service personnel only. No
user serviceable components inside.”) must be in English, German, Spanish, French,
Chinese, and Japanese with universal warning markings

3.2 Physical Dimensions

The power supply shall be enclosed and meet the physical outline shown in Figure 6,
as applicable. Mechanical details are shown in Figure 7. Details on the power supply
slot feature are shown in Figure 8. The recommended chassis slot feature details are
shown in Figure 9.

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Figure 6. Mechanical Outline

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Figure 7. Mechanical Details

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Figure 8. PSU Slot Feature Detail

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Figure 9. Recommended Chassis Tab Feature

3.3 AC Connector

The AC input receptacle should be an IEC 320 type or equivalent. In lieu of a
dedicated switch, the IEC 320 receptacle may be considered the mains disconnect.

3.4 DC Connectors

Figure 10 shows pin outs and profiles for typical power supply DC harness
connectors.

UL Listed or recognized component appliance wiring material rated min 85 °C, 300
VDC shall be used for all output wiring.

There are no specific requirements for output wire harness lengths, as these are
largely a function of the intended end-use chassis, motherboard, and peripherals.

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Ideally, wires should be short to minimize electrical/airflow impedance and simplify
manufacturing, yet they should be long enough to make all necessary connections
without any wire tension (which can cause disconnections during shipping and
handling). Recommended minimum harness lengths for general-use power supplies
is 150 mm for all wire harnesses. Measurements are made from the exit port of the
power supply case to the wire side of the first connector on the harness.

113

113

+3.3 VDC +3.3 VDC

+3.3 VDC +3.3 VDC
+3.3 VDC -12VDC

+3.3 VDC -12VDC
COM COM

COM COM
+5VDC PS_ON#

+5VDC PS_ON#
COM COM

COM COM
+5VDC COM

+5VDC COM
COM COM

COM COM
PWR_OK NC

PWR_OK NC
+5VSB +5VDC

+5VSB +5VDC
+12VDC +5VDC

+12VDC +5VDC
+12VDC +5VDC

+12VDC +5VDC
+3.3VDC COM

+3.3VDC COM

Mai n P owe r Connector

Mai n P owe r Connector

Figure 10. Connectors (Pin-side view, not to scale)

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3.4.1 Main Power Connector

Connector: MOLEX* Housing: 24 Pin Molex Mini-Fit Jr. PN# 39-01-2240 or
equivalent.

(Mating motherboard connector is Molex 44206-0007 or equivalent)

18 AWG is suggested for all wires except for the +3.3 V supply and sense return
wires combined into pin 13 (22 AWG).

Pin Signal Color Pin Signal Color

1 +3.3 VDC

2 +3.3 VDC Orange 14 -12 VDC Blue

3 COM Black 15 COM Black

4 +5 VDC Red 16 PS_ON# Green

5 COM Black 17 COM Black

6 +5 VDC Red 18 COM Black

7 COM Black 19 COM Black

8 PWR_OK Gray 20 Reserved NC

9 +5 VSB Purple 21 +5 VDC Red

10 +12 VDC Yellow 22 +5 VDC Red

Orange

13

[13]

+3.3 VDC

[+3.3 V default
sense]

Orange

[Brown]

11 +12 VDC Yellow 23 +5 VDC Red

12 +3.3 VDC Orange 24 COM Black

3.4.2 Peripheral Connector(s)

Connector: AMP
Contacts: AMP 61314-1 or equivalent.

Pin Signal 18 AWG Wire

1 +12 VDC Yellow

2 COM Black

3 COM Black

4 +5 VDC Red

*

1-480424-0 or MOLEX 8981-04P or equivalent.

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3.4.3 Floppy Drive Connector

Connector: AMP 171822-4 or equivalent

Pin Signal 20 AWG Wire

1 +5 VDC Red

2 COM Black

3 COM Black

4 +12 VDC Yellow

+12 V Power Connector

Connector: MOLEX 39-01-2040 or equivalent (Mating motherboard connector is

Molex 39-29-9042 or equivalent)

Pin Signal 18 AWG Wire Pin Signal 18 AWG Wire

1 COM Black 3 +12 VDC Yellow

2 COM Black 4 +12 VDC Yellow

3.4.4 Serial ATA Power Connector

This is a required connector for systems with Serial ATA* devices.

The detailed requirements for the Serial ATA Power Connector can be found in the
“Serial ATA: High Speed Serialized AT Attachment” specification, Section 6.3
“Cables and connector specification”. http://www.serialata.org/

Note: connector pin numbers and wire numbers are not 1:1. Carefully check to
confirm the correct arrangement.

Assembly: MOLEX 88751 or equivalent.

Wire Signal 18 AWG Wire

5 +3.3 VDC Orange

4 COM Black

3 +5 VDC Red

2 COM Black

1 +12 VDC Yellow

Wire #s

5
4
3
2

32

Figure 11. Serial ATA Connector

4 Thermal Requirements

4.1 Fan and Venting

The fan will draw air from the system enclosure and exhaust the air through a grill
located on the back panel.

The intake and exhaust grills of the power supply shall remain suitably free of
obstruction so as not to hinder airflow. The opening must be sufficiently protected
to meet the safety requirements of Section 6. It is recommended that a flush­mount wire fan grill be used to maximize airflow and minimize acoustic noise.

4.2 Airflow and Acoustics

LFX12V Power Supply Design Guide

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It is recommended but not required that the power supply be designed with an appropriate
fan, internal impedance, and fan speed control circuitry capable of meeting the airflow and
acoustic recommendations listed in Table 14.

Pure Tones: The power supply assembly shall not produce any prominent discrete tone
determined according to ISO 7779, Annex D.

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Table 14. Airflow and Acoustic Recommendations

T

PSU_INLET

46°C, sea level Test Condition 1 See:

DC output load Airflow

≥ 2.0 CFM ≤ 3.34 BA

• Table 15

• Table 16

for loadings

50°C, sea level Test Condition 2 See:

≥ 6.0 CFM ≤ 5.7 BA

• Table 15

• Table 16

for loadings

Notes:

(1) Airflow in cubic feet per minute (CFM) through the power supply to be measured per AMCA* Standard 210 (see

12).

(2) The declared sound power level shall be measured according to ISO 7779 for the power supply unit alone (i.e. not in a

system chassis) and reported according to ISO 9296.

(1)

Declared sound

power, LwAd

(2)

Figure

Table 15. Loading for Acoustic Test for 180 Watts

Loading condition +12V (A) +5V (A) +3.3V (A) -12V (A) +5Vsb (A) Total Power

(W)

Test Condition 1 5.5 3.0 2.0 0.1 1.0 93.8

Test Condition 2 11.0 5.5 4.0 0.2 1.0 180

Table 16. Loading for Acoustic Test for 200 Watts

Loading condition +12V (A) +5V (A) +3.3V (A) -12V (A) +5Vsb (A) Total Power

(W)

Test Condition 1 6.0 5.5 3.5 0.1 0.8 116

Test Condition 2 11.5 7.6 5.0 0.2 1.0 200

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Auxiliary Blower

Rectifying Grid

Nozzle Pressure

Auxiliary Blower is controlled to generate a zero Air Pressure
differential. Air Flow is determined from Nozzle pressure.

Nozzle

Power Supply
under Test

Air Pressure
differential.

Figure 12. AMCA* Standard 210

4.3 Airflow / Fan

The designer’s choice of a power supply cooling solution depends in part on the targeted
end-use system application(s). At a minimum, the power supply design must ensure its

own reliable and safe operation.
Fan location/direction: In general, exhausting air from the system chassis enclosure via a

power supply fan is the preferred, most common, and most widely applicable system-level
airflow solution. The location of the fan can have a large effect on how efficiently this air
is exhausted. The location of the fan shown in Figure 6 allows the fan to be located in an
effective manner to can aid in the evacuation of heated air and helps keep the total system
cooler.

Fan size/speed: The power supply can support up to a 70 mm axial fan. It is

recommended that a thermally sensitive fan speed control circuit be used to balance
system-level thermal and acoustic performance. The circuit typically senses the
temperature of the secondary heat sink and/or incoming ambient air and adjusts the fan
speed as necessary to keep power supply and system component temperatures within
specifications. Both the power supply and system designers should be aware of the
dependencies of the power supply and system temperatures on the control circuit response
curve and fan size and should specify them carefully.

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The power supply fan should be turned off when PS_ON# is de-asserted (high). In this
state, any remaining active power supply circuitry must rely only on passive convection for
cooling.

Venting: In general, more venting in a power supply case yields reduced airflow

impedance and improved cooling performance. Intake and exhaust vents should be as
large, open, and unobstructed as possible so as not to impede airflow or generate excessive
acoustic noise. In particular, avoid placing objects within 0.5 inches of the intake or
exhaust of the fan itself. A raised wire fan grill is recommended instead of a stamped
metal vent for improved airflow and reduced acoustic noise for the intake vent.

Considerations to the previous venting guidelines are:

• Openings must be sufficiently designed to meet the safety requirements described in

Section 5.

• Larger openings yield decreased EMI-shielding performance. The design should

always be tested per requirements outlined in Section 2.1.4.2.

NOTE:

Venting in inappropriate locations can detrimentally allow airflow to bypass those areas
where it is needed.

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5 Environmental

The following subsections define recommended environmental specifications and test
parameters, based on the typical conditions the power supply unit may be subjected to
during operation or shipment.

5.1 Temperature

Operating ambient: +10 °C to +50 °C (At full load, with a maximum temperature rate of

change of 5 °C/10 minutes, but no more than 10 °C/hr.)

Non-operating ambient: -40 °C to +70 °C (Maximum temperature rate of change of

20 °C/hr.)

5.2 Thermal Shock (Shipping)

Non-operating: -40 °C to +70 °C

15 °C/min ≤ dT/dt ≤ 30 °C/min. Tested for 50 cycles; Duration of exposure to temperature
extremes for each half cycle shall be 30 minutes.

5.3 Relative Humidity

Operating: To 85% relative humidity (non-condensing)
Non-operating: To 95% relative humidity (non-condensing)
Note: 95% RH is achieved with a dry bulb temperature of 55 °C and a wet bulb

temperature of 54 °C.

5.4 Altitude Requirement

Operating: To 10,000 ft
Non-operating: To 50,000 ft

5.5 Mechanical Shock

Non-operating: 50 g, trapezoidal input; velocity change ≥ 170 in/s

Three drops on each of six faces are applied to each sample.

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5.6 Random Vibration

Non-operating: 0.01 g²/Hz at 5 Hz, sloping to 0.02 g²/Hz at 20 Hz, and maintaining 0.02

g²/Hz from 20 Hz to 500 Hz. The area under the PSD curve is 3.13 gRMS. The duration
shall be 10 minutes per axis for all three axes on all samples.

5.7 Acoustics

Sound Power: See 4.2.

5.8 Ecological Requirements

The following materials must not be used during design and/or manufacturing of
this product:

Cadmium shall not be used in painting or plating.

Quaternary salt and PCB electrolytic capacitors shall not be used.

CFC’s or HFC’s shall not be used in the design or manufacturing process.

Mercury shall not be used.

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6 Safety

The following subsections outline sample product regulations requirements for a typical
power supply. Actual requirements will depend on the design, product end use, target
geography, and other variables. Consult your company’s Product Safety and Regulations
department for more details.

6.1 North America

The power supply must be certified by an NRTL (Nationally Recognized Testing
Laboratory) for use in the USA and Canada under the following conditions:

The supply must be Recognized for use in Information Technology Equipment

including Electrical Business Equipment per UL 1950 / CAN/CSA C22.2 No. 950-
95, renamed UL 60950, 3rd edition, without D3 deviations. The certification must

include external enclosure testing for the AC receptacle side of the power supply
(see Appendices A, B, C, and D).

The supply must have a full complement of tests conducted as part of the
certification, such as input current, leakage current, hi-pot, temperature, energy
discharge test, transformer output characterization test (open-circuit voltage, short­circuit current, and maximum VA output), and abnormal testing (to include stalled­fan tests and voltage-select–switch mismatch).

The enclosure must meet fire enclosure mechanical test requirements per clauses

2.9.1 and 4.2 of the above-mentioned standard.

100% production HiPot testing must be included and marked as such on the power
supply enclosure.

There must not be unusual or difficult conditions of acceptability such as
mandatory additional cooling or power de-rating. The insulation system shall not
have temperatures exceeding their rating when tested in the end product.

The certification mark shall be marked on each power supply.

The power supply must be evaluated for operator-accessible secondary outputs
(reinforced insulation) that meet the requirements for SELV and do not exceed 240
VA under any condition of loading.

The proper polarity between the AC input receptacle and any printed wiring boards
connections must be maintained (that is, brown=line, blue=neutral, and
green=earth/chassis).

Failure of any single component in the fan-speed control circuit shall not cause the
internal component temperatures to exceed the abnormal fault condition

temperatures per the IEC 60950 Specification.

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6.2 International

The vendor must provide a complete CB* certificate and test report to IEC 60950:1991, 2
edition + A1, A2, A3, and A4. The CB report must include ALL CB member country
national deviations. The CB report must include an evaluation summary to EN
60950:1992, + A1, A2, A3, A4 and Nordic deviations EMKO-TSE* (74-SEC) 207/94. All

evaluations and certifications must be for reinforced insulation between primary and
secondary circuits.

nd

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7 System Cooling Considerations

The power supply fan location allows the system designer to utilize the airflow to help cool
critical components such as the processor and chipset. Please note that the fan pulls air
from the system, instead of blowing hot air in, so components must be placed such that
airflow is directed across critical components. Cables, etc must not impede airflow.

For more information on system thermal design, please refer to

http://www.formfactors.org/

.

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8 Reliability

The de-rating process promotes quality and high reliability. All electronic components
should be designed with conservative device deratings for use in commercial and industrial
environments.

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9 Applicable Documents

The following documents support this design guide as additional reference material.

Document Title Description

AB13-94-146

ANSI* C62.41-1991
ANSI C62.45-1992

CSA C22.2 No.234, Level 3

CAN/CSA C22.2 No.950-95,
3rd edition

UL 1950, 3rd edition, without
D3 Deviation

IEC 60950, 2nd ed. 1991: plus
A1, A2, A3, A4

EN 60950, 2nd ed. 1992: plus
A1, A2, A3, A4

EMKO-TSE (74-SEC) 207/94
CISPR 22:1997 3rd edition

EN 55022:1998
ANSI C63.4 – 1992

European Association of Consumer Electronics Manufacturers (EACEM*)
Hazardous Substance List / Certification

IEEE* Recommended Practice on Surge Voltages in Low-Voltage AC Circuits

IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC
Power Circuits

Safety of Component Power Supplies (Intended for use with Electronic Data
Processing Equipment and Office Machines)

Safety of Information Technology Equipment Including Electrical Business
Equipment

Safety of Information Technology Equipment Including Electrical Business
Equipment

Safety of Information Technology Equipment Including Business Equipment

Safety of Information Technology Equipment Including Business Equipment

Nordic national requirement in addition to EN 60950

Limits and Methods of Measurements of Radio Interference Characteristics of
Information Technology Equipment, Class B

American National Standard for Methods of Measurement of Radio-Noise
Emissions from Low-Voltage Electrical and Electronic Equipment in the
Range of 9 kHz to 40 GHz for EMI testing

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Document Title Description

AS/NZS 3548 (Class B) Australian Communications Authority, Standard for Electromagnetic

Compatibility* (AU & NZ)

CNS* 13438

Limits and methods of measurement of radio disturbance characteristics of
Information Technology Equipment (Taiwan & China)

EN 55024:1998

Information technology equipment—Immunity characteristics—Limits and
methods of measurement

CISPR 24: 1997

Information technology equipment—Immunity characteristics—Limits and
methods of measurement

EN 61000-3-2

Electromagnetic compatibility (EMC)—Part 3: Limits—Section 2: Limits for
harmonic current emissions, Class D

IEC 61000-4-

Electromagnetic compatibility (EMC) for industrial-process measurement and
control equipment—Part 4: Testing and measurement techniques

Section -2: Electrostatic discharge
Section -3: Radiated, radio-frequency, electromagnetic field
Section -4: Electrical fast transient / burst
Section -5: Surge
Section -6: Conducted disturbances, induced by radio-frequency fields
Section -8: Power frequency magnetic fields
Section -11: Voltage dips, short interruptions, and voltage variations

Japan Electric Association*

Guidelines for the Suppression of Harmonics in Appliances and General Use
Equipment

IEC Publication 417
ISO Standard 7000
CFR 47, Part 15, Subpart B
ICES*-003 (Class B)
VCCI* V-3/99.05 (Class B)

International Graphic Symbol Standard

Graphic Symbols for Use on Equipment

FCC Regulations pertaining to unintentional radiators (USA)

Interference-Causing Equipment Standard, Digital Apparatus (Canada)

Implementation Regulations for Voluntary Control of Radio Interference by
Data processing Equipment and Electronic Office Machines (Japan)

44