Решения Littelfuse для защиты ETHERNET

Решения Littelfuse для защиты ETHERNET
ETHERNET PROTECTION DESIGN GUIDE
©2012 Littelfuse, Inc
1
ETHERNET PROTECTION DESIGN GUIDE
This guide was developed to help electronics designers navigate
the consideration factors and selection of appropriate circuit
protection components for Ethernet-equipped applications.
This document describes categories of Ethernet (including PoE Power over Ethernet), and presents example circuits, applicable
standards, and recommended components.
Table of Contents
Ethernet Basics .......................................................................................................................................................... 3
Introduction to PoE (Power over Ethernet) ................................................................................................................ 4
Overview of Testing Standards .................................................................................................................................. 5
Recommended Littelfuse Protection Devices ........................................................................................................... 6
Protection Guide ........................................................................................................................................................ 9
Data Line Protection ................................................................................................................................................. 10
ESD & EFT Indoor Short-Haul ............................................................................................................................ 10
Low Level Lightning, ESD & EFT Indoor Short-Haul ......................................................................................... 11
Lightning, ESD, EFT, CDE, Power Fault, Indoor Long-Haul............................................................................... 12
Lightning (Inter-building, Basic & Enhanced), ESD, EFT, CDE, Power Fault, Outdoor Exposure...................... 13
Lightning, General or Basic and Enhanced, ESD, EFT, CDE, Power Fault ........................................................ 14
Lightning, Severe Outdoor Exposure, ESD, EFT, Power Fault .......................................................................... 16
PoE PD (Powered Device) Protection or PoE PSE (Power Supply Equipment) Protection ..................................... 17
PoE PD & PSE lightning low to high exposure .................................................................................................. 17
PoE PD & PSE Outdoor exposure (high) ........................................................................................................... 18
Ordering Guide ....................................................................................................................................................... 19
Appendix A ............................................................................................................................................................... 20
Supplemental PoE and PoE+ .......................................................................................................................... 20
Appendix B ............................................................................................................................................................... 22
GR-1089 Issue 6 Ethernet type ports ............................................................................................................. 22
Appendix C ............................................................................................................................................................... 26
ITU-T K.20 & K.21 Ethernet type ports .......................................................................................................... 26
Appendix D ............................................................................................................................................................... 28
IEC 61000 Series Ethernet type ports ............................................................................................................ 28
IEC 61000-4-2 .................................................................................................................................................... 28
IEC 61000-4-5 .................................................................................................................................................... 29
YD/T 950-1998 .................................................................................................................................................. 30
YD/T 993-1998 .................................................................................................................................................. 31
YD/T 1082-2000 ................................................................................................................................................ 32
Appendix F ............................................................................................................................................................... 33
UL60950-1 / IEC60950-1 / EN60950-1 ............................................................................................................ 33
©2012 Littelfuse, Inc
2
ETHERNET PROTECTION DESIGN GUIDE
Ethernet Basics
Ethernet is a Local Area Network (LAN) that was standardized
as IEEE 802.3. There are four dominant forms in the
marketplace today with more on the horizon. These are
10Base-T, 100Base-T, 1000Base-T, and 10GBase-T (Base
stands for Baseband signaling, T stands for twisted pair, 10 =
10 Mbps, 100 = 100 Mbps, 100 = 1000 Mbps, 10G = 10Gbps).
All the standards use UTP (Unshielded Twisted Pair) wiring or
cabling such as CAT5, CAT5e, CAT6, and CAT7. Ethernet
connections are typically made with a RJ45 type connector,
which is also known as the IEC 60603-7 8P8C modular
connector.
Below lists differences between each of the four standards:
10Base-T
Data Rate
Symbol Rate
Data Pairs
Signaling
Encoding
Cabling
10 Mbps
20Mbaud with 0.5bits/baud
2 pairs out of the 4 available are used
(1 for transmit and 1 for receive)
Differential (i.e. 2 levels)
4B5B NRZ Manchester (four bits are scrambled and sent
as a 5 bit sequence)
CAT3 or higher up to 100M
Figure 1 below shows the two different connector designs
certified by the TIA (Telecommunications Industry Association)
with T568B being the most commonly used throughout the
world.
100Base-T (also known as Fast Ethernet)
Figure 1
Signaling
Data Rate
Symbol Rate
Data Pairs
Encoding
Cabling
100 Mbps
125Mbaud with 0.8bits/baud
2 pairs out of the 4 available are used (one pair for
transmit and one pair for receive)
Differential with MLT-3 (Multi Level Transition)
4B5B NRZ Manchester (four bits are scrambled and sent
as a 5 bit sequence)
CAT5 or higher up to 100M
1000Base-T
Data Rate
Symbol Rate
Data Pairs
Signaling
The main difference between the four forms of Ethernet is the
speed (see table at right). In general, the signaling scheme
became more complex to achieve the higher data rates. Figure
2 shows the differences in eye diagrams between a 100BaseT and 1000Base-T signal. The 10Base-T eye diagram was
omitted since it is a simpler, two-level signal. With this basic
understanding of Ethernet we will now move into an
introduction of Power-over-Ethernet which can be used in
conjunction with any of the aforementioned standards.
Figure 2
100Base-TX
©2012 Littelfuse, Inc
Encoding
Cabling
1000 Mbps
125Mbaud with 2bits/baud
4 pairs (full duplex) each pair carries 250 Mbps
Differential PAM-5 (Pulse Amplitude Modulation fivelevel) signaling
8B/10B
Preferably CAT5e or higher up to 100M
10GBase-T (10GbE)
Data Rate
Symbol Rate
Data Pairs
Signaling
Encoding
Cabling
10 Gbps
800M symbols/s
4 pairs (full duplex)
Differential PAM-16 (Pulse Amplitude Modulation sixteenlevel) signaling with CRC-8
DSQ128 (yields 3.5 bits per symbol)
Preferably CAT6 up to 55M or CAT6A/7 up to 100M
1000Base-T
3
ETHERNET PROTECTION DESIGN GUIDE
Introduction to PoE (Power over Ethernet)
PoE is a powering technique used over the existing Ethernet
wiring link. IEEE standard 802.3af specifies the technical
requirements so that systems are compatible with one another.
The IEEE 802.3at specification provides the guidelines for PoE+,
which is a higher power level than the original PoE. Both of these
specifications allow the Ethernet wiring to carry both data and DC
power. This removes the need for a local ac power port for each
individual Ethernet interface. PoE can also provide a continuous
power source thus supporting life-line capabilities for IP enabled
telephones such as may be seen in EFM (Ethernet in the First
Mile) or IEEE 802.3ah or Active Ethernet applications. This is also
known as Ethernet to the Home (ETTH). Life-line in this case
meaning that the telephone is not dependent on a local power
supply, so that it functions during local power outages. EFM
needs this capability in order to provide life-line service to
residential locations so PoE is an ideal implementation for EFM
applications.
Mode A
Mode A power is applied over the “active” data pair found in
10BaseT or 100BaseTX interfaces. In these type systems, two
pair are used for data delivery (RJ-45 pins: 1-2 and 3-6) and two
pair are unused (pairs 4-5 and 7-8). This is shown in Figure 3
below. PoE uses the “phantom powering” technique so that a
single pair carries a zero DC volt potential difference. The power
supply voltage is derived as the difference between two different
pair sets of wire. This method combines the DC voltage with the
signal over the transmit (TX) and receive (RX) pair. The two
center tap connections provide access to the DC power and the
DC voltage across any single pair (i.e. 1-2 or 3-6) remains at zero
volts. This scheme helps to prevent accidental shock hazards
when single pairs are handled.
Figure 3 (Mode A)
Here are two major advantages for PoE:
1)
Ethernet devices are not required to be placed next to wall
outlets and reduces the need for “wall-warts”
2)
Power cables are no longer required to be laid out for the
network
In a PoE scheme, the device that receives the power is called the
client device or Powered Device (PD) and the device supplying
the power is the Power Source Equipment (PSE). The IEEE
802.3af standard limits the PD power consumption to 12.95W
and limits the PSE power outputs to 15.4W on a per Ethernet
port basis. The network will contain patch panels and various
connectors that cause some current limiting restrictions.
Therefore, the IEEE 802.3af standard limits the maximum PSE
available current to 400mA per device connection and the PD
current to 360mA. This standard takes into account line losses for
maximum loop lengths of 100m, thereby allowing up to 57 VDC
from the PSE. The nominal level is 48 VDC. The PoE+ (IEEE
802.3at) allows the PSE to deliver up to 30W and the PD to
consume up to 25.5 W; with the PSE supplying up to a maximum
of 600mA. PoE+ also requires the use of low impedance wiring
(< 12.5 ohms per loop pair), such as CAT5e or CAT6.
This power can be inserted from (1) an endpoint PSE or (2) a midspan PSE. The legacy Ethernet systems most likely use a midspan PSE method. This prevents having to re-work the entire
network. For new installations, the endpoint PSE is the most
economical and easiest installation choice. Power can be
provided in one of two ways over CAT5e, CAT6, or CAT7 cable:
1)
Over the same pair used for data signaling in 10BaseT and
100BaseT systems, or
2)
Over the unused pair in 10BaseT and 100BaseT systems
©2012 Littelfuse, Inc
Mode B
Mode B power is applied over the unused pair (pairs 4-5 and 7-8)
for 10BaseT and 100BaseT interfaces. This is shown in Figure 4
below. For 1000BaseT and 10GbE applications, all wire pairs are
used for data transfer, therefore there are no “spare pairs”
available. So a 1000BaseT and 10GbE system may use either
Mode A or Mode B power but the 4-5 and 7-8 pair would be
center tap connected instead of directly connected. Mode B can
be used with any Ethernet application as can Mode A. The PD
end must be compatible with both Mode A and Mode B since its
final application is not known. The PSE defines the Mode type,
therefore it provides power in a single mode only; it cannot
provide power in both Mode A and Mode B simultaneously.
More detail regarding PoE can be found in Appendix A.
Figure 4 (Mode B)
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ETHERNET PROTECTION DESIGN GUIDE
Overview of Testing Standards
Depending upon the end use and environment, there are
various standards that will apply to a given Ethernet application.
Below are brief summaries of some the most common
standards encountered in the market today. More detailed
information about each standard can be found in the
associated Appendix noted below.
Isolation Requirements (IEEE 802.3)
To be compliant with IEEE802.3, an Ethernet port must
comply with the following electrical isolation strength test
(withstand at least one of the following tests):
1. 1500VRMS at 50Hz to 60Hz for 60s
2. 2250VDC for 60s OR
3. A waveshape impulse of 1.2/50-8/20µs 2400 volts applied
±10 times with at least one second interval between
successive surges (draft version indicates this may change
to 10/700-5/310 1500 volts applied ±10 times with at least
sixty second interval between successive surges)
Furthermore, all lightning waveshapes are described by their
peak value and tr x td as shown below.
There shall be no isolation breakdown during the test and the
resistance after test shall be at least 2 MΩ when measured at
500 VDC.
Immunity to Lightning, ESD, EFT, and Power Fault
There are many different regulatory standards used in
evaluating an Ethernet port’s susceptibility to damage from
electrical transients. The surge and ESD resistibility
compliance requirements are typically controlled by the local
governing bodies where the end equipment is being sold. The
standards listed by region are stated below:
Region
Standard
Note
North America
GR-1089 Issue6
Appendix B
Europe
ITU K.20 & K.21
Appendix C
IEC61000-4-2
International
IEC61000-4-4
Appendix D
IEC61000-4-5
China
YD/T 950-1998
YD/T 993-1998
YD/T 1082-2000
Appendix E
Whenever ESD is referenced in this document, it is assumed
the waveform is the same as defined by the IEC61000-4-2 for
the HBM (Human Body Model) standard seen below. In the
appendices there will be test voltages and currents shown for
the various levels/classes of ESD immunity.
©2012 Littelfuse, Inc
Power Faults
Included in the standards referenced above are the test levels
and conditions for power fault testing. Additional, safety
standards such as UL60950-1, IEC60950-1, and EN60950-1 are
intended to prevent personal injury or harm due to electrical
shock, energy hazards, fire, heat hazards, mechanical hazards,
radiation hazards, and chemical hazards. Please see Appendix
F for detailed information.
Every application is different and the specific protection
solution will be dependent upon several factors such as the
expected operating environmental conditions, geographical
location, transformer physical size/turns ratio/physical size,
length of the Ethernet cabling, use of shielded twisted pair
(STP)cable vs unshielded twisted pair (UTP) cable, local
standard rules and regulations, etc. The appendices
referenced above provide information about several worldwide specifications; however, feel free to contact Littelfuse for
clarification and further support at any time. Littelfuse
laboratory services are available for customer application
testing to provide evidence based solutions utilizing Littelfuse
recommended solutions. Contact your local Littelfuse
Representative to arrange such protection confirmation testing
using proven Littelfuse overcurrent and overvoltage protection
solutions.
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ETHERNET PROTECTION DESIGN GUIDE
Recommended Littelfuse Protection Devices
TVS Diode Arrays (SPATM Family)
Series
SP3002
SP3003
Schematic (Example)
ESD Level
(Contact)
±12kV
±8kV
I/O Cap
VR= 1.65V
0.85pF
(Line to Grd)
0.65pF
(Line to Grd)
VRWM
Lightning
(tP=8/20μs)
Number of
Channels
Package
Options
SC70-6
SOT23-6
6V
6V
4.5A
4
μDFN-6
1.6x1.6mm
2
SC70-5
SOT553
4
SC70-6
SOT563
MSOP-10
2.5A
SP3010
±8kV
0.45pF
(Line to Grd)
@ VR = 0
6V
3A
4
μDFN-10
2.5x1.0mm
SP3011
±8kV
0.4pF
(Line to Grd)
@ VR = 0
6V
3A
6
μDFN-14
3.5x1.35mm
SP3012
±12kV
.5pF
(Line to Grd)
5V
4A
4
μDFN-10
2.5x1.0mm
©2012 Littelfuse, Inc
6
ETHERNET PROTECTION DESIGN GUIDE
Recommended Littelfuse Protection Devices
TVS Diode Arrays (SPATM Family)
Series
Schematic (Example)
ESD Level
(Contact)
I/O Cap
VR= 0V
VRWM
Lightning
(tP=8/20μs)
Number of
Channels
Package
Options
6V
10A
4
SOT23-6
3.3V
75A
2
SOIC-8
(MS-012)
2.5V
20A
8
MSOP-10
2.5V
(Snap
Back
Voltage =
2.0V)
20A
4
µDFN-10
2.6x2.6mm
3.3V
(Snap
Back
Voltage =
2.8V)
20A
4
µDFN-10
2.6x2.6mm
1.2pF
SP3050
±20kV
(Line to Line);
2 pF
(Line to Grd
@ VR =1.65 V)
2.5pF
SP4040
±30kV
(Line to Line);
5 pF
(Line to Grd)
2.2pF
SP4060
±30kV
(Line to Line);
4.4 pF
(Line to Grd)
2pF
SP4061
±30kV
(Line to Line);
3.5pF
(Line to Grd)
2pF
SP4062
±30kV
(Line to Line);
3.5pF
(Line to Grd)
©2012 Littelfuse, Inc
7
ETHERNET PROTECTION DESIGN GUIDE
Recommended Littelfuse Protection Devices
TVS Diode Arrays (SPATM Family)
Series
Schematic (Example)
ESD Level
(Contact)
I/O Cap
VR= 0V
VRWM
Lightning
(tP=8/20μs)
Number of
Channels
Package
Options
3.3V
150A
2
SOIC-8
(MS-012)
3.3V
150A
2
SOIC-8
(MS-012)
2.8V
40A
1
SOT23-3
4
SOIC-8
(MS-012)
(JEDEC MO223 Issue A)
8pF
SP03-3.3
±30kV
(Line to Line);
16pF
(Line to Grd)
4.5pF
SP03A-3.3
±30kV
(Line to Line);
9pF
(Line to Grd)
±30kV
2.0pF
(Pin 2 to Pin 1)
±30kV
2pF
(Each line)
2.8V
MIN
[email protected]
IDRM=5μA
MAX
VS @100V/µs
MIN IH /
MAX IS
SEP008
6V
25V
50mA /
800mA
SEP0640
58V
77V
150mA /
800mA
SPLV2.8
SPLV2.8-4
40A
SIDACtor® Protection Thyristors
Series
Schematic (Example)
SEP0720
65V
88V
150mA /
800mA
SEP0900
75V
98V
150mA /
800mA
©2012 Littelfuse, Inc
Lightning
(tP=2/10μs)
Number of
Channels
Package
Options
500A
2
5x6mm
QFN
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ETHERNET PROTECTION DESIGN GUIDE
Protection Guide
Often equipment manufacturers are not sure what level of
protection they need or even what regulatory standards or
recommendations apply to their Ethernet ports. The matrix
below is an attempt to capture potential protection solutions
based on a “typical” application. The matrix below should not be
taken as authoritative, but merely as a guide to help narrow in on
a particular set of solutions. Please contact Littelfuse for an
assessment of your equipment and application to help make sure
the right solution is selected if you have any doubts or concerns
(www.littelfuse.com) or (+1) 773.628.1000.
End Application
Equipment
Small Office /
Home Office
Routers /
Switches
Enterprise
Remote Terminal
Central Office
Base Station /
Rooftop
ESD & EFT Indoor
Short-Haul
Lightning (Inter-building,
Basic & Enhanced), ESD,
EFT, CDE, Power Fault,
Outdoor Exposure
Lightning, ESD, EFT,
CDE, Power Fault,
Indoor Long-Haul
Lightning, Severe
Outdoor Exposure, ESD,
EFT, Power Fault
Data Line Protection
Low Level Lightning, ESD
& EFT Indoor ShortHaul
ONT
Modems
ESD & EFT
Indoor Short-Haul
Phones
(IP, PBX)
Lightning, ESD, EFT, CDE,
Power Fault, Indoor LongHaul
Lightning, General or Basic
and Enhanced, ESD, EFT,
CDE, Power Fault
Data Line Protection
Low Level Lightning, ESD
& EFT Indoor ShortHaul
Lightning, ESD, EFT, CDE,
Power Fault, Indoor LongHaul
Lightning, General or Basic
and Enhanced, ESD, EFT,
CDE, Power Fault
Lightning (Interbuilding, Basic &
Enhanced), ESD, EFT,
CDE, Power Fault,
Outdoor Exposure
Lightning (Interbuilding, Basic &
Enhanced), ESD, EFT,
CDE, Power Fault,
Outdoor Exposure
Lightning, Severe
Outdoor Exposure, ESD,
EFT, Power Fault
Solutions
Gateways
Lightning (Inter-building,
Basic & Enhanced), ESD,
EFT, CDE, Power Fault,
Outdoor Exposure
ESD & EFT Indoor
Short-Haul
PCs / Desktops
Set Top Boxes
LCD/PDP TVs
IP Cameras /
Security DVR
Lightning, ESD, EFT,
CDE, Power Fault,
Indoor Long-Haul
PoE
PoE PD & PSE
lightning
©2012 Littelfuse, Inc
Lightning, General or
Basic and Enhanced,
ESD, EFT, CDE, Power
Fault
Lightning (Inter-building,
Basic & Enhanced), ESD,
EFT, CDE, Power Fault,
Outdoor Exposure
Lightning, Severe
Outdoor Exposure, ESD,
EFT, Power Fault
PoE PD & PSE Outdoor
9
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
ESD & EFT Indoor Short-Haul
Applicable Standards:
● IEC 61000-4-2 (ESD), 4-4 (EFT)
● ESD & EFT Sections of GR-1089, ESD Sections of ITU-T, and YD/T 950 & 1082
Considerations:
● Some Ethernet ports only need to be protected from ESD and EFTs but not for lightning induced transients.
o These are sometimes referred to as 2m ports that have very short CAT5/5e cable installations
● Parasitic capacitance should be taken into account especially for 1GbE and higher
● The 4 data lines below (Tx± and Rx±) are being protected against ESD and EFTs by a low capacitance SP3002
o Any low capacitance SP30xx device is suitable for all “ESD and EFT exposure” Ethernet applications
● 1000Mbps Ethernet (or 1GbE) and 10GbE will require 8 channels of protection for the 4 differential pair so the solution
below should be replicated for the remaining 2 differential pair
Application Schematic:
RJ-45 Connector
Ethernet PHY
J1
Tx+
Tx-
Rx+
Rx-
J8
NC
SP3002
Case GND
Recommended TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=1.65V
# of Channels
VRWM
Packaging
SP3002-04JTG
±12kV
4.5A
0.85pF
4
6V
SC70-6
SP3003-04XTG
±8kV
2.5A
0.65pF
4
6V
SOT563
SP3012-04UTG
±25V
4A
0.5pF (@ 0V)
4
5V
μDFN-10
2.5x1.0mm
©2012 Littelfuse, Inc
10
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
Low Level Lightning, ESD & EFT Indoor Short-Haul
Applicable Standards:
● IEC61000-4-2 (ESD), 4-4 (EFT)
● ESD & EFT Sections of GR-1089, ESD Sections of ITU-T, and YD/T 950 & 1082
Considerations:
● Some Ethernet ports only need to be protected from ESD and EFTs but not for lightning induced transients.
o These are sometimes referred to as 2m ports that have very short CAT5/5e cable installations
● Parasitic capacitance should be taken into account especially for 1GbE and higher
● The 4 data lines below (Tx± and Rx±) are being protected against ESD and EFTs by a low capacitance SP3002
o Any low capacitance SP30xx device is suitable for all “ESD and EFT exposure” Ethernet applications
● 1000Mbps Ethernet (or 1GbE) and 10GbE will require 8 channels of protection for the 4 differential pair so the solution below
should be replicated for the remaining 2 differential pair
Application Schematic:
RJ-45 Connector
Ethernet PHY
J1
Tx+
Tx-
Rx+
J8
Rx-
NC
Case GND
SP3050
Recommended TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=0V
# of Channels
VRWM
Packaging
SP3050-04HTG
±20kV
10A
1.2pF
4
6V
SOT23-6
SP4061-04UTG
±30kV
20A
2pF
4
2.5V
μDFN-10
2.6x2.6mm
SP4062-04UTG
±30kV
20A
2pF
4
3.3V
μDFN-10
2.6x2.6mm
©2012 Littelfuse, Inc
11
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
Lightning, ESD, EFT, CDE, Power Fault, Indoor Long-Haul
Applicable Standards:
● GR-1089, Intra-Building (Type 2, 3a, 3b, 5a, 5b)
● ITU-T K.20 Internal Ports & YD/T 950-1998
● ITU-T K.21 Internal Ports & YD/T 993-1998
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
•
If the SP03 device is used on the line side of the coupling transformer, then ground reference pins 2, 3, 6, and 7 should not be
connected to ground to comply with the isolation requirements of the IEEE 802.3 standard. Some debate remains on the specific
requirements, since references in IEEE 802.3 quote the UL 60950-1 isolation testing procedures, which allows removal of any
surge protection connected to ground during isolation testing. Please consult with your specific compliance testing labs to review
this.
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950 power fault requirements.
Lightning Immunity Requirements:
•
•
•
The 4 data lines below (Tx± and Rx±) are protected against intra-building lightning transients (100A, tP=2/10µs for up to 2 pair,
1.2/50-8/20 36.4A per wire for 4 pair).
The SP03A diverts the majority of energy away from the transformer, but any common mode energy that does get coupled across
the transformer interwinding capacitance will be diverted to GND by the SP3050. The SP3050 can be connected to ground on the
PHY side of the transformer since the IEEE 802.3 isolation requirements are met by the transformer itself.
1000Mbps Ethernet (or 1GbE) and 10GbE will require 8 channels of protection for the 4 differential pair so the below scheme
should be replicated for the remaining 2 differential pair.
Application Schematic:
RJ-45 Connector
Ethernet PHY
F1
J1
Tx+
F2
Tx-
Rx+
F3
J8
RxF4
SP03A (x2)
F1:F4 = 0461 1.25 TeleLink Fuse
PHY GND
SP3050
Recommended TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=0V
# of Channels
VRWM
Packaging
SP03A-3.3BTG
±30kV
150A
4.5pF (I/O to I/O)
2
3.3V
SOIC-8
SP3050-04HTG
±20kV
10A
2.4pF (I/O to GND)
4
6V
SOT23-6
©2012 Littelfuse, Inc
12
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
Lightning (Inter-building, Basic & Enhanced), ESD, EFT, CDE, Power Fault, Outdoor Exposure
Applicable Standards:
● GR-1089, Inter-Building (Type 1, 3, 5)
● ITU-T K.20 and YD/T 950-1998 (Enhanced Requirements)
● ITU-T K.21 and YD/T 993-1998 (Enhanced Requirements)
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
•
The SEP device located on the line side of the transformer may have pins 3 and 6 floating in order to be compliant with the IEEE
802.3 isolation requirements. Some debate remains on the specific requirements, since references in IEEE 802.3 quote the UL
60950-1 isolation testing procedures, which allows removal of any surge protection connected to ground during the isolation
testing. Please consult with your specific compliance testing labs to review this.
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950/1082 power fault requirements.
Lightning Immunity Requirements:
•
•
•
The 4 data lines below (Tx± and Rx±) are being protected against GR-1089 Type 3b/5b inter-building lightning transients (1000V,
200A, 2/10µs & 1000V, 25A 10/360µs).
The SEP diverts the majority of energy away from the transformer, however, any common mode energy coupled through the
transformer interwinding capacitance will be returned to GND by the SP4062 shown below. The SP4062 can be connected to
ground since it is positioned behind the transformer and thus complies with the IEEE 802.3 isolation requirements.
1000Mbps Ethernet (or 1GbE) and 10GbE will require 8 channels of protection for the 4 differential pair so the scheme below
should be replicated for the remaining 2 differential pair.
o
In this case the SP4060-08ATG may be a more suitable option to replace (2x) SP4062 devices IF the Ethernet PHY device
signaling voltage is < 2.0 V (this is the snap-back voltage value of the SP4060 device). The SP4062 device has a snap-back
voltage of 2.8, thus it can be used on Ethernet PHY devices with signaling voltages < 2.8 V.
Application Schematic:
RJ-45 Connector
F1
*Package is shown as transparent
Ethernet PHY
J1
Tx+
Tx-
F2
SP4062
PHY
GND
F3
J8
Rx+
Rx-
F4
F1:F4 = 0461 1.25 TeleLink Fuse
SEP0xx (x2)
Recommended SIDACtor and TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=0V
# of
Channels
VRWM
Packaging
SEP0080Q38CB
±30kV
400A
See datasheet
2
6V
QFN
SP4062-04UTG
±30kV
20A
3.5pF
4
3.3V
µDFN-10 (2.6x2.6mm)
SP4060-08ATG
±30kV
20A
4.4pF
8
2.5V
MSOP-10
©2012 Littelfuse, Inc
13
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
Lightning, General or Basic and Enhanced, ESD, EFT, CDE, Power Fault
Applicable Standards:
●
●
●
●
GR-1089, Intra/Inter-Building (Type 1, 2, 3, 3a, 3b, 5, 5a, 5b)
ITU-T K.20 and YD/T 950-1998 (Basic & Enhanced Requirements)
ITU-T K.21 and YD/T 993-1998 (Basic & Enhanced Requirements)
YT/D 1082
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
●
Not applicable.
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950/1082 power fault requirements.
Lightning Immunity Requirements:
•
•
•
•
Some designers choose to use a high voltage transformer in their design to act as the first line of protection against an incoming
surge event. This is usually done to minimize the parasitic capacitance on the data line and to save on the cost of the secondary
(line side) protector.
Using such a technique will require a robust PHY side protection device and one such option is the SPLV2.8-4BTG shown below. It
should be noted that this device will only provide differential protection between the data pairs.
If longitudinal and differential protection are required, the SP4062-04UTG (with 2 I/O’s tied per line) or SP4060-08ATG (if the PHY
line driving voltage is < 2.0 V) can be considered as alternatives.
Protection for Fast Ethernet (100Mbps) is shown below. For 1000Mbps (or 1GbE) and 10GbE interfaces, 2x SPLV2.8-4BTG are
required
Application Schematic:
RJ-45 Connector
J1
Ethernet PHY
F1
Tx+
Tx-
F2
Rx+
RxF3
SPLV2.8-4
*Package is shown as transparent
F4
J8
Recommended TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=0V
# of Channels
VRWM
Packaging
SPLV2.8-4BTG
±30kV
40A
2.0pF
4
2.8V
SOIC-8
SP4062-04UTG
±30kV
20A
3.5pF
4
3.3V
µDFN-10 (2.6x2.6mm)
SP4060-08ATG
±30kV
20A
4.4pF
8
2.5V
MSOP-8
©2012 Littelfuse, Inc
14
ETHERNET PROTECTION DESIGN GUIDE
©2012 Littelfuse, Inc
15
ETHERNET PROTECTION DESIGN GUIDE
Data Line Protection
Lightning, Severe Outdoor Exposure, ESD, EFT, Power Fault
Applicable Standards:
●
●
●
●
GR-1089, Inter-Building (Type 1, 3, & 5)
ITU-T K.20 and YD/T 950-1998 (Enhanced Requirements)
ITU-T K.21 and YD/T 993-1998 (Enhanced Requirements)
YT/D 1082
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
•
The GDTs (Gas Discharge Tubes) are connected between the data pair (and not GND) to be compliant with the IEEE802.3 standard.
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950/1082 power fault requirements.
Lightning Immunity Requirements:
•
•
•
Some customers have applications that may see severe levels of lightning that exceed the limits of today’s silicon technology.
For these applications (e.g. >500A, 2/10µs or 400A 1.2/50-8/20) a GDT is recommended to protect the transformer along with very
robust protection device to suppress the let-through energy at the PHY.
The SL0902A090SM (1.5pF, 5000A, 8/20µs) is shown below along with the SP03A-xBTG for PHY protection. A single SP406008ATG or two SPLV2.8-4 may be considered as an alternate solution but would NOT be as robust as the SP03A for 1GbE and
10GbE applications.
Application Schematic:
Ethernet PHY
RJ-45 Connector F1
J1
Tx+
F2
TxSL0902A090SM
Rx+
F3
J8
RxF4
SP03A (x2)
F1:F4 = 0461 1.25 TeleLink Fuse
PHY GND
Recommended TVS Diode Arrays SPATM Devices:
Ordering Number
ESD Level
(Contact)
Lightning
(tP=8/20μs)
I/O Capacitance @
VR=0V
# of Channels
VRWM
Packaging
SP03A-3.3BTG
±30kV
150A
9pF
2
3.3V
SOIC-8
SP4040-02ATG
±30kV
75A
5pF
2
3.3V
MS-012
SPLV2.8-4BTG
±30kV
40A
2.0pF
4
2.8V
SOIC-8
SP4060-08ATG
±30kV
20A
4.4pF
8
2.5V
MSOP-8
©2012 Littelfuse, Inc
16
ETHERNET PROTECTION DESIGN GUIDE
PoE PD (Powered Device) Protection or PoE PSE (Power Supply Equipment) Protection
PoE PD & PSE lightning low to high exposure
Applicable Standards:
● GR-1089, Intra-Building (Type 2)
● ITU-T K.20 Internal Ports & YD/T 950-1998
● ITU-T K.21 Internal Ports & YD/T 993-1998
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
•
Not applicable
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950 power fault requirements.
Lightning Immunity Requirements:
•
For low exposure intra-building PoE applications, the SMAJ58A (400W or 4.3A @ 10/1000 µs) provides both Mode A and Mode B
protection when the diode bridge is implemented as shown below for the PD. For the PSE, only four diodes would be needed as
the PSE defines whether Mode A or Mode B is used. An alternative method would be to place a single SMAJ58CA (bi-directional
version) across the center tap signal pair and a second SMAJ58CA across the center tap spare pair. For the PSE, a single
SMAJ58CA would be used, since the PSE controls whether Mode A or Mode B powering is used. The bi-directional version
SMAJ58CA is used to insure no polarity issues and thus does not require the diode bridge polarity guard circuit. The SMBJ58A
(58CA) version would provide a higher surge rating solution (600W or 6.5A @ 10/1000 µs), the SMCJ58 (58CA) would provide the
next surge rating increase (1500W or 16.1A @ 10/1000 µs) and the SMDJ58A (58CA) version would provide another increase in
surge rating (3000W or 32.1A @ 10/1000 µs).
•
The TeleLink fuses (0461 1.25ER) F1-F4 will comply with the power fault requirements and NOT open during lightning surge
events.
•
Small form-factor, chip fuses can also be selected for F1 and F4 when protection of PSE ONLY requires over-current protection for
safety reasons and is not subjected to Intra-building surges. At the 57V, 600mA maximum power PoE+ requirement, the circuit
falls under IEC60950-1, Limited Power Source, Sec 2.5, Table 2B. The maximum output current must be limited to 2.63A in 5 sec if
a PTC is used and in 60sec if a fuse is used. For standard PoE (400ma), the recommended over-current device for F1 and F4 is the
2016L075/60MR PTC or the 0468001.NRHF. fuse. For PoE+ (600ma), the recommended over-current device for F1 and F4 is the
0468001.NRHF.fuse.
Application Schematic:
©2012 Littelfuse, Inc
17
ETHERNET PROTECTION DESIGN GUIDE
PoE PD Protection or PoE PSE Protection
PoE PD & PSE Outdoor exposure (high)
Applicable Standards:
● GR-1089, Inter-Building (Type 1, 3 & 5)
● ITU-T K.20 & K.21
● YD/T 950-1998, 993, & 1082
● IEC61000-4-5 (Class0 - 4)
● IEC61000-4-2 (ESD) & 4-4 (EFT)
● UL60950-1 / IEC60950-1 / EN60950-1
Isolation Requirements:
•
Not applicable
Power Fault Requirements:
•
The TeleLink fuses F1-F4 provide overcurrent protection that complies with the GR-1089, ITU K20/21, UL60950-1 / IEC60950-1 /
EN60950-1 and YD/T 950 & 1082 power fault requirements.
Lightning Immunity Requirements:
•
For high exposure inter-building PoE applications, the SEP0640Q38CB can provide both Mode A and Mode B protection for the PD
equipment without the need of an external diode bridge. Normally pins 2 & 7 of the SEP device are used for biasing purposes but
in this application these two pins are connected together via PCB traces and used as part of the protection solution. For a PSE
solution, only pins 4/5, and 3/6 would be used since the Mode is defined by the PSE side.
•
The TeleLink fuses F1-F4 (0461 1.25ER) will comply with the power fault requirements but NOT open during lightning surge
events.
Application Schematic:
©2012 Littelfuse, Inc
18
ETHERNET PROTECTION DESIGN GUIDE
Ordering Guide
Series
Number of Channels
SP3002
4
2
SP3003
4
Package
Orderable Part Number
SOT23-6
SP3002-04HTG
SC70-6
SP3002-04JTG
μDFN-6 (1.6x1.6mm)
SP3002-04UTG
SC70-5
SP3003-02JTG
SOT553
SP3003-02XTG
SC70-6
SP3003-04JTG
SOT563
SP3003-04XTG
MSOP-10
SP3003-04ATG
SP3010
4
μDFN-10 (2.5x1.0mm)
SP3010-04UTG
SP3011
6
μDFN-14 (3.5x1.35mm)
SP3011-06UTG
SP3012
4
μDFN-10 (2.5x1.0mm)
SP3012-04UTG
SP3050
4
SOT23-6
SP3050-04HTG
SP4040
2
SOIC-8 (MS-012)
SP4040-02BTG
SP4060
8
MSOP-10
SP4060-08ATG
4
μDFN-10 (2.5x1.0mm)
2
SOIC-8 (MS-012)
SPLV2.8
1
SOT23-3
SPLV2.8HTG
SPLV2.8-4
4
SOIC-8
SPLV2.8-4BTG
SP4061
SP4062
SP03-3.3
SP03A-3.3
SEP008
SEP0640
SEP0720
SEP0900
©2012 Littelfuse, Inc
SP4061-04UTG
SP4062-04UTG
SP03-3.3BTG
SP03A-3.3BTG
SEP0080Q38CB
2
5x6mm QFN
SEP0640Q38CB
SEP0720Q38CB
SEP0900Q38CB
19
ETHERNET PROTECTION DESIGN GUIDE
Appendix A
Supplemental PoE and PoE+
Table 1: PoE vs PoE + Voltage/current values
The PoE specification provides a "handshaking" routine between
the PSE (Power Supply Equipment) and the PD (Powered Device)
PARAMETER
MIN
MAX
before power is applied. This insures power compatibility and
PoE PSE Voltage Range
44V
57V
helps to prevent safety violations. The PSE can apply power to the
PoE+ PSE Voltage Range Type 1
44 V
57 V
wire pairs only when an attached device has indicated its ability to
receive power. This “handshaking” routing is known as Resistive
PoE+ PSE Voltage Range Type 2
50 V
57 V
Power Discovery. It relies on a 25kΩ (nominal) resistance that is
PoE
PSE
Current
Range
400
mA
part of the network devices. The PSE will test the resistance of
the network device before sending full power onto the wiring pair.
PoE+ PSE Current Range
350 mA
600 mA
This test is conducted with a series of two low-voltage “discovery”
PoE PD Voltage Range
36V
57V
signals. The second signal uses a slightly higher voltage than the
PoE+ PD Voltage Range Type 1
37.0 V
57 V
first, but neither is enough to damage an incompatible device.
After the PSE has determined that IEEE 802.3af/at compliant
PoE+ PD Voltage Range Type 2
42.5 V
57 V
devices are connected, it injects power to those ports. It will not
PoE PD Current Range
360 mA
send power to devices that failed either of these two resistance
PoE+ PD Current Range
350 mA
600 mA
tests. An IEEE 802.3af compliant PSE can source up to 15.4W (PD
can accept up to 13 W)while an IEEE 802.3at compliant PSE can
source up to 30W (PD can accept up to 25.5W). Table 1 below
Table 2: Valid PD Signature Parameters for PoE (IEEE 802.af)
contrasts the differences between PoE and PoE+ allowed
voltages and currents.
PARAMETER
CONDITIONS (V)
MIN
MAX
V-I slope
-2.7 to -10.1
23.7kΩ
26.3kΩ
These “discovery” signals require the PSE to conduct voltageVoltage offset
1.9V
current measurements with a current limited voltage probe
Current
offset
10µA
technique. When the probing voltage is applied, then the
appropriate values must be detected to discern that a valid load
exists BEFORE power can be applied. Table 2 below shows these
requirements for IEEE 802.af while Table 2a shows the signature
parameters for PoE+ (IEEE 802.at). The main difference between
these two powering schemes is the maximum cable loop
resistance limit for PoE+ is reduced to 12.5 ohms from 20 ohms
for PoE. The Type 1 PoE+ is almost exactly the same as PoE,
while PoE+ Type 2 takes advantage of the higher power delivery.
Signature
Capacitance
-2.7 to -10.1
0.05µF
0.12µF
Input inductance
-2.7 to -10.1
-
100mH
Table 2a: Valid PD Signature Parameters for PoE+ (IEEE 802.at)
PARAMETER
V-I slope
Voltage offset
Current offset
Input Capacitance
Input inductance
CONDITIONS (V)
-2.7 to -10.1
-2.7to -10.1
-2.7 to -10.1
MIN
23.7Ω
0V
0µA
0.050µF
-
MAX
26.3kΩ
1.9V
10µA
0.120µF
100mH
The PSE also detects the power classification of the client devices
by applying a probing voltage between for up to 75ms. The PD
device indicates its power classification (one out of four currently
available classes as shown in Table 3 and 3a below). This
information allows the PSE to intelligently manage power delivery
and prevents PD’s power requirements from exceeding the PSE’s
ability. Under this scenario, an intelligent PSE can refuse to
deliver any power to the port under question until the PD power
classification is met. This can also provide a method of prioritizing
ports to be powered during UPS or backup generator operation
©2012 Littelfuse, Inc
20
ETHERNET PROTECTION DESIGN GUIDE
Appendix A (continued)
Table 3: PD Power Classifications and Signatures for PoE (IEEE 802.3af)
CLASS
0
(Default)
1
2
3
4
(Reserved
for future
use)
CONDITIONS
(V)
CLASSIFICATION
CURRENT (mA)
PD POWER
RANGE
(W)
-14.5 to -20.5
0 to 4
0.44 to 12.95
-14.5 to -20.5
-14.5 to -20.5
-14.5 to -20.5
9 to 12
17 to 20
26 to 30
0.44 to 3.84
3.84 to 6.49
6.49 to 12.95
-
-
-
Table 3a: PD Power Classifications and Signatures for PoE+ (IEEE
802.3at)
CLASS
0
1
2
3
4*
CONDITIONS
(V)
CLASSIFICA-TION
CURRENT (mA)
PD
POWER
AVG
(W)
PD
Type
-14.5 to -20.5
-14.5 to -20.5
-14.5 to -20.5
-14.5 to -20.5
-14.5 to -20.5/ 6.90 to -10.1
0 to 4
9 to 12
17 to 20
26 to 30
13.0
3.84
6.49
13.0
1
1
1
1
36 to 44
25.5
2
* The PoE+ Type 2 returns a Class 4 classification signature
The PSE will constantly monitor the connected clients in order to
maintain power. For PoE, a PD must draw a minimum current of
10mA for at least 75ms out of a 250ms period and continue to
present an input resistance of no more than 26.3kΩ. If the
current drawn falls below this minimum threshold, the PSE will
disconnect the -48V supply and restart the detection sequence.
(Most PoE PD devices draw 100mA to 300mA). It will also
disconnect for excessive current draw for the PD’s classification.
The PSE may also provide a probing AC voltage up to 500Hz and
disconnect if minimum values are not maintained (27kΩ at 5mA
max is a valid impedance).
The resulting voltage level the PSE is allowed to apply is between
-44V to -57V. The PD device will see between -36V and -57V,
depending on the length and category type of cable used.
©2012 Littelfuse, Inc
The PDs and PSEs must provide an electrical isolation that can
withstand at least one of the following to be fully compliant to
the IEEE 802.3af/at standard:
1)
2)
3)
1500 VRMS at 50Hz to 60Hz for 60s
2250 VDC for 60s OR
An impulse of 2400V, with a voltage waveshape of
1.2x50µs applied ±10 times with a 60s interval between
successive surges
There shall be no insulation breakdown during the test and the
resistance after test shall be at least 2 MΩ when measured at
500 VDC. The IEEE 802.3at PoE+ 2009 version actual states a
1500V, 10/700µs waveshape but it is expected that this will be
modified to agree with the IEEE 802.3af standard.
These voltage levels used during the discovery processes along
with the electrical isolation requirements provide the minimum
longitudinal turn on voltage threshold for any protection devices
placed across an Ethernet pair on the line side of the coupling
(isolating) transformer.
Any clamping or crowbarring device placed across a wire pair
used for power delivery must not react nor interfere with these
handshaking routines. This requires voltage activated surge
protection devices located on the line side of the isolating
transformer in a PoE application to NOT turn on;
1) For one of the following (user’s choice): common mode
1500VRMS, 2250 VDC or 2400V 1.2/50-8/20µs surge
2) between pairs during classification testing voltage worse
case, which is 20.5V
3) between pairs or common mode due to highest possible
PSE voltage, which could be - 57 VDC
4) differentially for normal operating condition of the Ethernet
data signal, which is typically less than 5V
5) between pairs for the original discovery voltage of 10.1 volts
Therefore, it can be seen that strict adherence to IEEE 802.3
does NOT allow for common mode protection on the line side of
the coupling transformer other than the transformer itself.
However, IEEE 802.3 refers to the insulation test requirements in
subclause 5.2.2 of UL 60950-1, which allows removal of any
common mode connected overvoltage protector BEFORE
conducting the surge insulation test. Therefore, it is
recommended that the user consult with their compliance
department or compliance testing professional to determine the
correct interpretation for their application.
21
ETHERNET PROTECTION DESIGN GUIDE
Appendix B
GR-1089 Issue 6 Ethernet type ports
ESD (Electrostatic Discharge)
The EUT (equipment under test) shall be tested using the
methods of IEC 61000-4-2 (ESD), clauses 7 and 8, with the
preferred method being the contact discharge method as
specified in clause 7. The EUT shall not be damaged and shall
continue to operate without negatively affecting service or
requiring the need for manual intervention. Examples of test
points includes: panels, doors, exposed frame areas, consoles,
pushbuttons, keypads, faceplates, extractor tabs, lamps, LEDs,
circuit breakers, accessible fuses and fuse holders, metallic
covers of D-subminiature connectors, and test-plug jacks.
ESD Test Conditions
Test Level
2
4
4
Air Discharge
4kV
15kV
---
Contact Discharge
----8kV
Repetition
±20*
±20*
±10*
*For a total of 40 times for air discharge or a total of 20 times for contact
discharges
EFT (Electrical Fast Transient)
The EUT shall be tested using the methods of IEC 61000-4-4
(EFT). The EUT shall not be damaged and shall continue to
operate without negatively affecting service or requiring the need
for manual intervention. Five single minute burst test of each
polarity as shown below are applied.
Peak voltage
250 volts
500 volts
500 volts
1,000 volts
Port Type
1&2
3&4
Non-customer premises ac & dc
ports
Customer premises ac & dc ports
Repetition Rate
5 kHz or 100 kHz
(higher frequency
is closer to actual
field conditions)
Lightning Immunity
GR-1089 contains 1st Level and 2nd Level Inter-building and IntraBuilding test conditions. The specific surge condition depends on
the port type.
Port Type Number
Description
1
Network Inter-building
2
3a
Network Intra-building
Customer premises (CP) inter-building and cell
site locations
Intra-building cell site CP ports
3b
Short reach Outside Plant (OSP) CP ports*
4
CP intra-building
4a
Customer side ONT intra-building
5
OSP inter-building
3
5a
Intra-cell site
5b
Short reach OSP ports
6
Antenna ports
7
AC power ports
8
Local DC power ports
8a
DC power to antenna
8b
Intra-cell DC power
* Typically less than 500 feet
Ethernet ports are most commonly intra-building port types but
can be Type 1, 2, or 3 depending on their connection
environment. All Ethernet ports are subjected to metallic and
longitudinal surges and power fault testing with the exception of
Type 2 Ethernet ports. The following Type 2 Ethernet ports are
subjected to only longitudinal (common mode) type surges IF it
meets the following criteria:
a) LAN cabling that is not connected to external ports
b) LAN equipment powered from a single power feed
c) There are no ground referenced SPDs installed
d) It is a non-PoE interface.
For the 10/100 BaseT Ethernet interfaces some wire pairs are not
used for data but will have a “Bob Smith” termination circuit.
These “unused” pairs are also tested and the termination
components cannot be damaged since their failure could result in
increased radiation emissions. PoE interfaces also have their
inter-powering wire pair surge tested. PoE pairs are also surge
tested.
©2012 Littelfuse, Inc
22
ETHERNET PROTECTION DESIGN GUIDE
Appendix B (continued)
1st Level Inter-building (Type 3b/5b surge test #1 & 2 only)
Surge #
Peak Voltage Minimum (V)
Peak Current Minimum (A)
1
±1000
25
2
@±Vs of secondary protector
[email protected] 1000V
3
±100 to ±1000 (100V increments)
10 to 100
4
±1000 to ±2000
100 to 200
5
±2500
500
6
@±Vs of secondary protector
[email protected] 1000V
7
±4000
100
1st Level Port Types 3 & 5 (3b/5b surge #1 only)
Surge #
Peak Voltage Minimum (V)
Peak Current Minimum (A)
1
±1000
200
2
±1000
100
3
±400 to ±4000 (high exposure)
50 @ 400V; 500 @ 4000V
Waveshape
10/360
±5
10/1000
2/10
10/1000
10/700-5/310
±10
Waveshape
2/10
Reps
10/1000
1st Level Intra-building surges for Port Types 2, 3a/5a. 4, 4a with three and four wire pairs
(test 1 & 3 for unshielded PoE)
Surge #
Peak Voltage Minimum (V)
Peak Current Minimum (A)
Waveshape
44.4/three wire pair
1
±800 (external 6 ohms per wire)
36.4/four wire pair
47/three wire pair
2
±1500 (external 20 ohms per wire)
1.2/50-8/20
42/four wire pair
3
100 @ 800V
±Vs
4
68 @ 1500V
1st Level Intra-building surges for Port Types 2, 3a/5a. 4, 4a with more than four wire pairs
(test 1 & 3 for unshielded PoE)
Surge #
Peak Voltage Minimum (V)
Peak Current Minimum (A)
Waveshape
±800 (external 6 ohms per wire)
1
< 36/wire
metallic only
±1500 (external 40 ohms per wire)
2
<42/wire
1.2/50-8/20
longitudinal only
3
100 @ 800V
±Vs
4
35.7 @ 1500V
©2012 Littelfuse, Inc
Reps
±5
±5
Reps
±5
Reps
±5
23
ETHERNET PROTECTION DESIGN GUIDE
Appendix B (continued)
Shielded Cable Testing
For Equipment Port Types 2, 3a/5a, 4, 4a, or 8b that use a shielded cable that is grounded and bonded to earth ground at both ends,
then the following tests are conducted instead of those outlined above using the figure below for the surge generator connections.
Surge #
Peak Voltage Minimum (V)
1
±1500
Peak Current Minimum (A)
750 (before external 2-ohm is added
resulting in 375 total)
Waveshape
Reps
1.2/50-8/20
±5
The Type 2 Ethernet ports are exempted from metallic (differential) testing IF
1) the port does not contain a grounded secondary protector
2) any unused pins are not grounded (Bob Smith termination is not considered as a grounded connection in this context)
Type 4 and 4a are exempted from the metallic testing until August 1, 2012.
2nd Level surges for Port Types 1, 3, and 5
Surge #
Peak Voltage Minimum (V)
1
±5000
©2012 Littelfuse, Inc
Peak Current Minimum (A)
500
Waveshape
2/10
Reps
±5
24
ETHERNET PROTECTION DESIGN GUIDE
Appendix B (continued)
GR-1089 Issue 6 Power Fault
Power companies and telephone operating companies often
share telephone poles and trenches; therefore, network
equipment is often subjected to the voltages seen on power
lines. If direct contact between the Ethernet port and the primary
power line occurs, the Ethernet port could see as much as
600VRMS for up to five seconds. If direct contact occurs with the
secondary power line, voltages will be limited to 277VRMS;
however, these secondary voltages may persists indefinitely
since the resultant current may not be sufficiently high enough to
cause the power system to reset itself. Indirect contact between
the Ethernet line and the power line may result in
1st Level Power Fault Tests (Port Types 1, 3, & 5)
Min voltage peak
Min current per
Test #
value (V)
conductor (A)
1
50
0.33
2
Vs
0.33 @ 50 V
3
100
0.17
4
Vs
0.17 @ 100 V
5
200
0.47
6
425
1
7
Vs
1 @ 425 V
8
1000
1
9
425
0.50
10
425
0.71
large voltages being induced upon the Ethernet line (the large
power line currents can create interfering magnetic fields).
Primary protectors should limit these levels to 1000V peak and
600VRMS. Issue 6 assumes a high voltage category primary
protector is always replacing the older 3-mil carbon-gap
technology. This newer technology limits the 60 Hz events to 425
V rms (600 V peak). As a result of this newer technology being
used, the power fault events are limited to a lower peak voltage
level as reflected in the following two tables. For intra-building
applications, the power fault is limited to the normal household
voltage level of 120 volts.
Reps
Duration
1
15 minutes
Test Connections
Metallic and
longitudinal
60
1s
1
5
4s
2s
Longitudinal
Metallic &
longitudinal
Vs tests are conducted at the primary protector maximum voltage breakdown with the primary protector removed from the circuit.
*For more on test connections please refer to the Littelfuse SIDACtor catalog
Notes:
1. For EUT containing secondary voltage limiting and current limiting protectors, tests are to be performed at the indicated voltage(s) and repeated at a reduced voltage and
current just below the operating threshold of the secondary protectors.
2. Sufficient time may be allowed between applications to preclude thermal accumulation.
2nd Level Power Fault (Port Types 1, 3, & 5; Test 1 at 120V also applies to Port Types 3a, 3b, 4, 4a, 5a, & 5b)
Test
1
2
3
4
5
6
Applied Voltage,
60Hz (VRMS)
120, 277
425
425
425
Vs
Vs
Short Circuit Current
per Conductor (ARMS)
25
40
7, 10, 12.5, 20, 25, & 30
2.2, 2.6, 3.0, 3.75, & 5
Vs/60.7
Vs/193.2 & at 2.2
Duration
Test
Connections*
15min
5s
5s
15min
5s
15 min
Metallic and longitudinal
*For more on test connections please refer to the Littelfuse SIDACtor catalog.
Notes:
1. Primary protectors are removed for all tests.
2. For EUT containing secondary voltage limiting and current limiting protectors, tests are to be performed at the indicated voltage(s) and repeated at a reduced voltage and
current just below the operating threshold of the secondary protectors.
3. These tests are repeated using a short-circuit value just below the operating threshold of the current limiting device, or, if the EUT uses a fuse as current limiting
protection, the fuse may be bypassed and the short circuit current available adjusted to 135 percent of the fuse rating.
©2012 Littelfuse, Inc
25
ETHERNET PROTECTION DESIGN GUIDE
Appendix C
ITU-T K.20 & K.21 Ethernet type ports
ITU-T, the Telecommunication Standardization Sector of the ITU,
developed fundamental testing methods that cover various
environmental conditions to help predict the survivability of
network and customer-based equipment. The testing methods
cover the following conditions:
1. Surges due to lightning strikes on or near twisted pairs and
plant equipment (excluding a direct strike)
2. Short-term induction of an AC voltage from adjacent power
lines or railway systems
3. Direct contact between telecommunication lines and power
lines (often referred to as AC power fault)
4. ESD events as outlined in IEC 61000-4-2 and EFT events as
outlined in IEC 61000-4-4
Two ITU-T Recommendations apply for most
telecommunications equipment:
However, for complex subscriber equipment, test administrators
may choose either K.20 or K.21, depending on which is deemed
most appropriate. ITU K20 and K21 contain tests for both
external and internal ports.
Note: Both specifications are intended to address equipment
resistibility to lightning induced events, liability versus equipment
safety. For specific concerns regarding equipment safety,
research and follow national standards for each country in which
the equipment is intended for use.
Equipment submitted under either of these two
Recommendations must meet one of two levels: basic or
enhanced. Guidelines for determining which level of these two
levels are appropriate for the equipment under test (EUT) can be
found in ITU-T K.11, but the final authority rests with the test
administrator. ITU-T K.44 describes the test conditions used in
K.20 and K.21.
1. ITU-T K.20
2. ITU-T K.21
ITU-T defines the following acceptance criteria:
ITU-T K.20 is primarily for equipment located in the
telecommunication centers where the bonding and grounding is
installed according to ITU K.27 Recommendation.
Criterion A states that equipment shall withstand the test
without damage and shall operate properly after the test without
an operator or user manual intervention. It is not required to
operate correctly during the test.
K.21 covers telecommunication equipment installed at customer
premises.
Criterion B states that a fire hazard must not occur as a result of
the tests. Any damage shall be confined to a small part of the
equipment and it shall not emit hot materials and any flame
occurrence shall not propagate beyond the equipment.
Lightning Immunity
K. .20 Lightning Test Conditions for Ethernet Equipment in Central Office/Remote Terminal and connected to external ports
Voltage (10x700μs)
Current (5x310μs)
Primary
Acceptance
Single Port Metallic
Multiple Ports
Basic/Enhanced
Repetitions*
Protection
Criteria
and Longitudinal
Longitudinal Only
(A)
Basic/Enhanced
Basic/Enhanced
1kV / 1.5kV
25 / 37.5
±5
None **
A
Agreed primary protector is
installed and primary to
4kV / 4kV
100 / 100
±5
A
secondary coordination is
required
1.5kV / 1.5kV
37.5 / 37.5
±5
None**
A
Agreed primary protector is
installed and primary to
4kV / 6kV
100 / 150
±5
A
secondary coordination is
required
©2012 Littelfuse, Inc
26
ETHERNET PROTECTION DESIGN GUIDE
Appendix C (continued)
Lightning Immunity (continued)
K. 21 Lightning Test Conditions for Ethernet Equipment in Customer Premises connected to external ports
Voltage (10x700μs)
Current (5x310μs)
Primary
Single Port Metallic
Multiple Ports
Basic/Enhanced
Repetitions*
Protection
and Longitudinal
Longitudinal Only
(A)
Basic/Enhanced
Basic/Enhanced
1.5kV / 1.5kV (6 kV
25 / 37.5 (150)
±5
None **
longitudinal)
Agreed primary protector
is installed and primary
4kV / 6kV
4kV / 6kV
100 / 150
±5
to secondary
coordination is required
1.5kV / 1.5kV
37.5 / 37.5
±5
None**
* One-minute rest between repetitions ** Test not conducted if primary protection is used
IEC 61000-4-2 ESD ±5 air discharges at Level 3 are required for
the Basic test level and at Level 4 for Enhanced test level for
both ITU K.20 and K.21. IEC 61000-4-2 ESD ±5 contact
Acceptance
Criteria
A
A
A
discharges at Level 3 are required for the Basic test level and at
Level 4 for Enhanced test level for both ITU K.20 and K.21.
K.20/21 Lightning Test Conditions for Ethernet Equipment Internal ports
Voltage (1.2/50μs)
Shielded Cable
Current (8/20μs)
Unshielded Cable
Basic/Enhanced
Basic
Basic/Enhanced
Simultaneous
(A)
simultaneous
longitudinal w/conductor
longitudinal
& shield connected
27.7 (K.20) per wire (for
500V / 1000V (K.20)
four conductor interfaces)
1000V/1500 V (K.21)
55.56 (K.21)
500V / 1000V (K.20)
250 (K.20) per wire
1000/1500 (K.21)
500 (K.21)
Current (8/20μs)
Enhanced
(A)
Repetitions*
Acceptance
Criteria
±5
A
±5
A
55.56 (K.20) per wire (for
four conductor interfaces)
83.34 (K.21)
500 (K.20) per wire
750 (K.21)
Power Fault
K.20/K.21 Power Fault Test Conditions for Ethernet Ports connected to external ports (Metallic and Longitudinal)
Voltage
Basic/Enhanced
Current
Basic/Enhanced
Duration
Basic/Enhanced
Repetitions *
Primary
Protection
Acceptance Criteria
Basic/Enhanced
600V/600 V 50 or 60Hz
1/1
0.2s
5
None
A/A
600V/1.5kV 50 or 60Hz
1 / 7.5
1s / 2s
5
None
A/A
230V/230V 50 or 60Hz
23 / 23
B/B
11.5 / 11.5
B/B
5.75 / 5.75
B/B
2.975 / 2.875
1.44 / 1.44
15min
1
None
B/B
B/A
0.77 / 0.77
B/A
0.383 / 0.383
B/A
0.23 / 0.23
B/B
* One-minute rest between repetitions
©2012 Littelfuse, Inc
27
ETHERNET PROTECTION DESIGN GUIDE
Appendix D
IEC 61000 Series Ethernet type ports
IEC 61000-4-2
The IEC 61000-4-2 defines test procedures to evaluate equipment ESD resistibility performance.
IEC61000-4-2: ESD Test Levels
Level
Contact Discharge
Air Discharge
Voltage
1
2kV
2kV
2
4kV
4kV
3
6kV
8kV
4
8kV
15kV
x
Special
Special
IEC 61000-4-2: ESD Test Current Values vs. Time
Level
Voltage
1
2kV
2
4kV
3
6kV
4
8kV
Rise Time
0.7-1ns
Peak Current
Current at 30ns
Current at 60ns
7.5A
4A
2A
15A
8A
4A
22.5A
12A
6A
30A
16A
8A
IEC 61000-4-2: Guidelines for Test Selection
Class
Relative Humidity as low as
Anti-Static Material
Synthetic Material
Maximum Voltage
1
35%
X
2kV
2
10%
X
4kV
3
50%
X
8kV
4
10%
X
15kV
The test level chosen for a particular application should consider its installation and environmental conditions.
©2012 Littelfuse, Inc
28
ETHERNET PROTECTION DESIGN GUIDE
Appendix D (continued)
IEC 61000-4-5
Lightning Immunity (IEC 61000-4-5)
This standard defines test procedures to evaluate equipment
immunity to uni-directional surges resulting from electrical
switching and nearby lightning strikes. The switching transients
are associated with power system switching disturbances, and
various system faults. The lightning transients are associated
with direct lightning strikes to an outdoor circuit; indirect lightning
strikes such a cloud to cloud, and nearby lightning strikes.
IEC 61000-4-5: 10/700-5/320 generator
Waveform
Description
Voltage
Waveform
Current
Waveform
Output
Impedance
Open Circuit
Voltage
Short Circuit
Current
Repetition
Rate
CWG of ITU K
10 x 700µs
5x 320µs
40Ω
500V to 4kV
12.5A to 100A
1/minute
IEC 61000-4-5: Guidelines for Test Level Selection
Class
Description
0
Well-protected, generally considered intra-building (Surge Voltage < 25 V)
1
Partly protected (Surge Voltage < 500 V)
2
Cables well separated (Surge Voltage < 1000 V)
3
Cables run in parallel (Surge Voltage < 2000 V)
4
Outside connections running along with power (Surge Voltage < 4000 V)
5
Telecommunication cables and overhead power lines in non-dense populated areas
X
Special conditions as specified in the product requirements
IEC 61000-4-5: Test Level Selection Criteria
Test Levels
Installation
Class
PoE (dc power supply)
Unshielded Ethernet
Shielded Ethernet
Metallic
Longitudinal
Metallic
Longitudinal
Metallic
Longitudinal
0
NA
NA
NA
NA
NA
NA
1
NA
NA
NA
500V
NA
NA
2
NA
NA
NA
1kV
NA
500V
3
1kV^
2kV*^
NA
2kV*^
NA
2kV^
4
2kV^
4kV*^
NA
2kV*^
NA
4kV^
5
2kV
4kV*
NA
4kV*^
NA
4kV^
* Tested with primary protection
^ For cable < 10 m this test level may be lowered by one level
CLASS 1-5 uses the 10/700µs / 5x320µs for Ethernet circuits (symmetrical communication lines).
©2012 Littelfuse, Inc
29
ETHERNET PROTECTION DESIGN GUIDE
Appendix E
YD/T 950-1998
YD/T 950-1998 establishes the technical requirements and test
methods for protection against overvoltages and overcurrents on
telecommunication switching equipment for Mainland China.
This Standard is based on the ITU-T Recommendation K.20
“Resistibility of Telecommunications Equipment Installed in a
Telecommunications Center for Overvoltages and Overcurrents”
(1996 version). It was approved by the Ministry of Information
Industry of the People’s Republic of China on August 7, 1998 and
has been in effect since September 1, 1998.
After the following tests are conducted, the equipment should
provide normal communications functions and comply with these
requirements.
Without primary protection:
1. When the lightning waveform is 10/700μs and the peak
voltage is 1kV
2. When the induction voltage of the power line is 600VRMS
and the duration is 0.2s
With primary protection:
1. When the lightning waveform is 10/700μs and the peak
voltage is 4kV
2. When the induction voltage of the power line is 600VRMS
and the duration is 1s
After the equipment is tested for contact discharge at an
electrostatic voltage of 6 kV or for air discharge at 8 kV, it should
provide normal communications functions.
Power Faults
Time between successive events shall be one minute.
Without primary protection: 600V, 1A, 0.2s applied between Tip
and Ring to Ground 5 times
Characteristics and parameters shall be tested within 30 minutes
after the completion of these events
With primary protection: 600V, 1A, 1s applied between Tip and
Ring to Ground 5 times
ESD (Electrostatic Discharge)
Indicated
Voltage
Peak of Initiation of the
Discharge Currents, IP
Rise Time During Discharge
Switch On / Off (tR)
Current at
20 ns (I1)
Current at
60 ns (I2)
6kV
22.5A ± 10%
0.7–1ns
12A ± 30%
6A ± 30%
±5 repetitions direct contact with one-second duration between successive discharges
±5 repetitions indirect contact (0.1m distance) with one second duration between successive discharges
Lightning Immunity
Peak
Voltage
Peak
Current
Number of
Tests
Primary
Protection
Tip to Ring Grounded
1kV
25 A
±5
No
Ring to Tip Grounded
1kV
25 A
±5
No
1kV
25 A
±5
No
4kV
100A
±5
Yes
Ring to Tip Grounded
4kV
100A
±5
Yes
Tip and Ring to Ground
4kV
100A
±5
Yes
Tip and Ring to Ground*
1kV
25 A
±5
No
Testing Terminals
Voltage /
Current Waveform
Tip and Ring to Ground
Tip to Ring Grounded
10x700µs /
5x310µs
* Simultaneous surge for 50% of the ports
©2012 Littelfuse, Inc
30
ETHERNET PROTECTION DESIGN GUIDE
Appendix E (continued)
YD/T 993-1998
YD/T 993-1998 establishes the technical requirements and test
methods for lightning protection of telecommunication terminal
equipment for Mainland China. This Chinese Standard parallels
the ITU-T K.21 “Resistibility of Subscriber’s Terminal to
Overvoltages and Overcurrents” (1996) document very closely.
This standard is the technical basis for simulated lightning
induced event testing requirements for Telecommunication
Terminal Equipment such as modems, fax machines, telephone
sets, and so on. Normal operation of EUT is not required during
the lightning surge simulation test. However, all functions of the
EUT should meet the requirements of relevant standards after
the completion of these tests.
Lightning Immunity
Lightning Surge Test Conditions
Without
Primary
Protection
Metallic Test
Voltage / Current
Waveform
Test Voltage / Current*
(kV/A)
1.5 / 37.5
Single Tip and Ring Pair
Single Tip and Ring Pair
1 / 25
Longitudinal Test
All Tip and Ring Pair
10x700µs / 5x310µs
With
Primary
Protection
Metallic Test
Longitudinal Test
Single Tip and Ring Pair
Single Tip and Ring Pair
4 / 100
All Tip and Ring Pair
* All tests are conducted ±5 times with at least one minute between events.
©2012 Littelfuse, Inc
31
ETHERNET PROTECTION DESIGN GUIDE
Appendix E (continued)
YD/T 1082-2000
YD/T 1082-2000 establishes the technical specifications on
overvoltage and overcurrent protection of access network
equipment for Mainland China. This Chinese Standard parallels
the ITU-T K series. This standard specifies the technical
requirements and test methods for overvoltage and overcurrent
protection and the basic environmental adaptability of access
network equipment. This Standard does not deal with protection
against radiated electromagnetic fields. The specifications as
presented here are a succinct summary of the lightning surge,
power fault, and ESD testing required by this document. The
ports of the Network equipment are classified into five
categories:
I.
Ports used to connect the twisted pairs introduced from
outside of the building, namely analog user interface, ISDNBRA interface, ADSL interface, and so on
Twisted pair ports used to interconnect the different
equipment inside the building, namely V.24 interface, V.35
interface, 2048kbps interface connected to twisted pairs,
10/100 Base-T Ethernet interface, and so on
Coaxial cable port: 2048kbps interface connected to coaxial
cables, ISDN-PRA interface, and so on
AC Power interface
DC power interface
II.
III.
IV.
V.
Power Faults
Tested Port
I
I
Number of Ports
Central Office
Remote
3
--1
---
Test Conditions
600V, 600Ω, 50Hz, 1s
220V, 50Hz, 1h, 600/200/10Ω
ESD (Electrostatic Discharge)
Indicated
Voltage
Peak of Initiation of the
Discharge Currents, IP
Rise Time During Discharge
Switch On / Off (tR)
Current at
20 ns (I1)
Current at
60 ns (I2)
6kV
22.5A ± 10%
0.7–1 ns
12A ± 30%
6A ± 30%
±5 repetitions direct contact with one-second duration between successive discharges
±5 repetitions indirect contact (0.1m distance) with one second duration between successive discharges
Lightning Immunity
Class of Port
I
II
III
IV
V
Number of Ports
Central Office
Remote
3
--8
1
1
1
1
--1
1
1
©2012 Littelfuse, Inc
Voltage / Current
Waveforms
10/700µs x 5/310µs
1.2x50µs / 8x20µs
Amplitude*
4kV
6kV
500V
500V
10kV (5kA)
500 V
32
ETHERNET PROTECTION DESIGN GUIDE
Appendix F
UL60950-1 / IEC60950-1 / EN60950-1
This safety standard is intended to prevent injury or harm due to
electrical shock, energy hazards, fire, heat hazards, mechanical
hazards, radiation hazards, and chemical hazards. For the USA
market, the National Electric Code (NEC) implemented Article
800-4, which mandates that “all equipment intended for
connection to the public telephone network be listed for that
purpose” in order to ensure electrical safety. A manufacturer can
meet this requirement by listing their product with Underwriters
Laboratories under UL 60950-1 (based on IEC 60950-1,). The NEC
requires all telecommunication wiring that enters a building to
pass through a primary protector, which is designed to limit AC
transients in excess of 600VRMS. These transients are due to the
fact that telephone lines run in close proximity to AC power lines.
Most telecommunication equipment uses a secondary
overvoltage protector such as the SIDACtor device. The
secondary devices typically limit transients in excess of 350VRMS.
Therefore, a potentially dangerous condition exists because of
the voltage threshold difference of the primary protector and the
secondary protector. To minimize this danger, compliance with
UL 60950-1 is required. UL 60950- 1 covers equipment with a
rated voltage (primary power voltage) not exceeding 600 V and
equipment designed to be installed in accordance with the NEC
NFPA 70. This standard does not apply to air-conditioning
equipment, fire detection equipment, power supply systems, or
transformers.
UL 60950-1 Annex A (this is a National Deviation applicable specifically to North America) Overvoltage Test
Test
L1
L2
L3
L4
L5
M1
M2
M3
M4
Voltage (VRMS)
600V
600V
600V
See Note 1
120V
600V
600V
600V
See Note 1
Current (A)
40
7
2.2
2.2
25
40
7
2.2
2.2
Time
1.5s
5s
See note 2
See note 2
See note 2
1.5s
5s
See note 2
See note 2
Comments
Reduce to 135% fuse rating
Reduce to 135% fuse rating
Reduce to 135% fuse rating
Reduce to 135% fuse rating
Notes:
1
Voltage < conduction voltage of protection
2
Test for 30 minutes or until an open circuit occurs unless it appears possible that risk of fire or safety hazard may result; then continue test until
ultimate results are obtained (maximum 7 hours).
General Notes:
- ISDN S/T interface only L1, L2, L5, M1, and M2.
- If Test 3 resulted in open condition, bypass the fuse, reduce current to 135% of the fuse rating and continue the test.
- L4 and M4 are conducted at a voltage level just below Vs only if SIDACtor VS ≥285 VS.
- For test conditions M1, L1, M5, and L5 a wiring simulator (MDL 2 A fuse) is used.
- Compliance means no ignition or charring of the cheesecloth, and/or wiring simulator does not open.
- Tests 2, 3, and 4 are required only if the unit is not a fire enclosure.
- EUT shall continue to comply with the requirements of Clause 6.2 (Separation requirements and electric strength requirements) at the conclusion of
these overvoltage tests.
Littelfuse, Inc.
8755 West Higgins Road
O’Hare Plaza, Suite 500
Chicago, IL 60631 USA
Phone: (773) 628-1000
www.littelfuse.com
[email protected]
Authored by: Chad Marak & Phillip Havens
©2012 Littelfuse, Inc
33
ETHERNET PROTECTION DESIGN GUIDE
©2012 Littelfuse, Inc
34
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