Application Design Center - Power Line Network
97 - unlinked - Circuit Protection of Ethernet Port
Solutions
Design Notes:
- Protection Application:
- The data signals used in an Ethernet port vary between 1.0V (100 and 1,000 BaseT) to 2.5V (10BaseT), with maximum data rates of 125Mbps and 12.5Mbps, respectively. At these data rates, the capacitance of the suppressor needs to be taken into account. The signal lines to be protected from ESD include T+/- and R+/-.
- Solution Description:
- As shown at the left, discrete multilayer varistors can be used for board layout flexibility, or to reduce part count, a single rail clamp array can be used.
- Companion Solutions:
- Other solutions within the Littelfuse portfolio exist in addition to these recommendations. For example, if the design engineer knows that no additional capacitance can be added to the system, the PulseGuard® suppressor family can be consulted.
- Regulatory Issues:
- The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.
- Unique Features:
- Does not apply.
- Application Warnings:
- This protection scheme is only for Ethernet ports that connect to a LAN. If the Ethernet network will include access to the outside of the building, then more stringent standards apply to take into account lightning surges. Please consult Littelfuse recommendations for Ethernet and Intrabuilding surge protection.
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