System Description
2
TIDUES1A – October 2019 – Revised February 2020
Copyright © 2019–2020, Texas Instruments Incorporated
EMC Compliant 10/100-Mbps Ethernet PHY Reference Design With IEEE
802.3at Type-1 (
≤
12.95 W) PoE-PD
1
System Description
Currently, an IP-based Ethernet network infrastructure is already in place, which means an IP-enabled
device can easily be connected to the network. Simply setup the IPd address and you are up and running.
Adding more IP-enabled devices to a network is as easy as the first one. From the installation perspective,
there can be scenarios where you need to run a longer cable that may lie beyond the standard Ethernet
distance limitation of 100 m (328 feet). Some examples may include large commercial buildings (shopping
malls, offices, hospitals, airports, or schools), industrial and manufacturing applications, transportation
systems, security and surveillance gates, and so on. Effective cable length, what we finally get is only
about 90 m for horizontal runs because a good general rule during installation is to leave 10 m for the
patch cabling. This restricted reach can severely limit the viable locations where system designers and
implementers may want to operate a remote IP-enabled device. For example, IP surveillance networks
behave slightly different than traditional networks. As IP surveillance cameras and network video
recorders (NVR) continue to improve, the demand for extended high-data-rate transmission with minimum
data loss has become increasingly important in IP surveillance networks. Due to the standard 100-m
limitation of Ethernet, many network installers and system integrators have to rely on Ethernet extender
solutions to deploy IP surveillance networks. Challenges include the additional cost for the Ethernet
extender and also the need to ensure that the Ethernet extender solutions purchased can withstand high
frequencies, large data packet transmission, and high-power consumption to support IP video and mega-
pixel transmission.
For any IP-enabled device to function, it requires both Ethernet and power. It is often desirable and
required to install a remote IP-enabled device in a location where electrical power is not available. This is
where Power-over-Ethernet (PoE) technology supplies a solution. PoE is a mechanism for supplying
power to network devices over the same cabling used to carry network traffic. Therefore, no infrastructure
upgrade is necessary. PoE technology saves time and cost of installing separate power cabling, AC
outlets and wall warts, as well as eliminates the need for a dedicated UPS for individual devices.
The industrial environment is very different from the commercial environment and poses its own set of
challenges. Industrial environments often include harsh conditions like higher temperature ranges and
voltages, higher noise, mechanical stress, and so forth. Deploying IP network cameras or any other IP-
enabled device, whether indoor or outdoor, requires a robust protection scheme to safeguard the
equipment against electrical transient threats often encountered at the system level – lightening-induced
surge, electro-static discharge (ESD), and electrical fast transient (EFT). All semiconductor devices are
susceptible to Electrostatic Discharge (ESD) events. Devices that interface to the outside world are at
greater risk than devices that interface with a piece of equipment internally. Since the Ethernet network
connection is often very long and typically made of Unshielded Twisted Pair (UTP) cable, the Ethernet
interface is also prone to an additional ESD event called Cable Discharge Event (CDE). A CDE during the
UTP cable installation can be destructive to the Ethernet PHY device.
Enabled by Texas Instruments’ IEEE 802.3-compliant Ethernet PHY transceiver to support 10Base-Te and
100Base-TX protocols, power management devices and high-speed interface protection circuitry, this
reference design demonstrates how to design a robust Ethernet communication interface supporting
10/100 Mbps data and power delivery (IEEE 802.3at, Type-1) together over longer cable length for harsh
industrial environment with regards to standard compliance to CISPR 22 (EN 55022) Class A and B
radiated emission requirements and conducted immunity requirements for ESD according to 61000-4-2
and fast transient burst (EFT) according to IEC61000-4-4.
This design guide addresses component selection, design theory, and test results of the reference design
system. The scope of this design guide gives system designers a head-start in integrating TI’s devices into
their end-equipment systems. This reference design provides a complete set of downloadable documents
such as comprehensive design guide, schematic, Altium PCB layout files, Gerber files, bill of materials
(BOM) and test results that helps system designers in the design and development of their end-equipment
systems. The following subsections describe the various blocks within the reference design system and
what characteristics are most critical to best implement the corresponding function.