Ethernet cables can carry common-mode noise from a PCB into the external environment. They can also conduct ESD and other disturbances toward the equipment.
Use the topology and values recommended for the selected PHY and magnetics. Do not automatically connect the common node to digital ground.
PoE Thermal Check
python
def winding_loss(current_a, dcr_ohm):
return current_a ** 2 * dcr_ohm
for current in [0.35, 0.60, 0.96]:
print(current, winding_loss(current, 0.30))

DCR balance matters because unequal voltage drops can disturb pair balance and create different temperature rises.
Pre-Compliance Workflow
json
{
"schematic_reviewed": true,
"layout_reviewed": true,
"near_field_scan": true,
"emissions_pretest": true,
"esd_pretest": true,
"link_recovery_logged": true,
"configuration_documented": true
}

CISPR 32 addresses multimedia-equipment emissions, while IEC 61000-4-2 defines an ESD immunity test method. Applicable requirements and test levels depend on the complete product and market.
Voohu Technology supplies network transformers, LAN magnetics and RJ45 connectors. Prototype orders can start from 50 pieces, with BOM cross-reference support and typical three-to-five-day DHL delivery subject to stock and destination.
More information: Voohu Technology
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