MagJack Integrated Magnetics RJ45 Sourcing
1 resources tagged with "Magjack"
A MagJack is an RJ45 jack with the Ethernet magnetics (isolation transformer) integrated into the connector housing, saving board space versus discrete magnetics. The transformer quality is the hidden variable when sourcing from China — undersized or mis-wound magnetics cause return-loss failures and PoE problems that don't show until field testing. Genuine integrated-magnetics jacks for Gigabit (1000BASE-T) cost noticeably more than knockoffs that skimp on the transformer.
Sourcing MagJacks means treating the magnetics, not the housing, as the part you're buying — we ask for return-loss and insertion-loss data and verify PoE contact ratings, because a jack that mechanically fits can still fail isolation. Counterfeit Bel/Pulse-style parts with inferior transformers are common.
Wiki (1)
FAQ
What is a MagJack and why use one?
It's an RJ45 connector with the Ethernet isolation magnetics built in, so you don't place discrete transformers on the board. It saves space and simplifies layout, but shifts the magnetics quality risk into the connector you source.
What goes wrong with cheap integrated-magnetics jacks?
Under-spec transformers cause return-loss failures, link-speed drops, and PoE faults that only appear under load. Ask for the magnetics test data and confirm PoE contact current ratings before approving.
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