Technical articles and news about LAN Transformers, newest first.
A LAN transformer (Ethernet magnetics) isolates and matches the Ethernet port. In essence it is a set of 1CT:1CT high-frequency isolation transformers plus common-mode chokes: it couples the PHY differential signals to the cable side while providing isolation and common-mode noise suppression.
Because it affects both signal integrity and EMC, selection cannot stop at data rate and package. Narrow down the series by data rate, PoE, PHY drive type and package first, then read OCL, insertion loss, return loss, common-mode rejection and DCR in the datasheet, and finally set the isolation rating by the operating environment.
10/100, Gigabit, 2.5G / 5G and 10G LAN transformers have different parameters; start from the PHY data rate.
For voltage-mode PHYs the center tap goes to ground through a capacitor; for current-mode PHYs it goes to the PHY supply. Follow the PHY reference circuit for the turns ratio, which is 1CT:1CT in most cases.
With PoE, look at OCL under DC bias and at the PoE current rating, so the core does not saturate and the port does not overheat at full load.
DIP or SMD; single, dual or quad port; pin count, pitch and height against the PCB footprint. Choose the isolation voltage for indoor, industrial or outdoor use.
Values are typical requirements for Gigabit LAN transformers; the datasheet of each part number governs.
The usual minimum for Gigabit LAN transformers is 350 µH at 100 kHz, 100 mV. With PoE you must check OCL under DC bias: the DC current lowers the inductance and can saturate the core, so choose a part rated for your PoE current.
For ordinary indoor ports, the IEEE 802.3 baseline of 1500 Vrms for 60 seconds is enough. For PoE, noisy industrial sites, long cables or outdoor ports, go to 2000–3000 Vrms and add proper surge protection.
Follow the PHY datasheet. Most PHYs use 1CT:1CT; a few require a different ratio, and the wrong one causes amplitude mismatch and link negotiation problems.
Usually not. A common cause is the center-tap capacitor across the isolation barrier being rated too low, or too little creepage on the PCB. Replace that capacitor with one rated 2 kV or higher and test again.
A dead Ethernet port after a surge does not necessarily mean the LAN transformer failed. How surges reach the port, a power-off method that measures each side o
A full comparison of the 23 chip LAN order codes VOOHU offers across six sizes. 2012 and 3216 are Cap+CMC and contain no transformer at all; only 3532A, 4532B,
Compare WHDG18110G and WHDG18101G insertion-loss limits, centre taps, pin mapping and board-level checks before approving an 18-pin Gigabit LAN transformer repl
Compare four VOOHU quad-port Gigabit LAN transformers by 72-, 88- and 96-pin footprints, pitch, PoE capability and operating temperature.
Understand differential pairs, pairsets and ports, then select a VOOHU LAN Transformer by data rate, port count and PoE current rating.
Select dual-port Gigabit LAN magnetics by pin count, mounting, PoE and temperature, then validate both ports concurrently.
1. Competitor Product Overview (CND-tek) A single-port Gigabit PoE+ interface has four differential channels to manage. Its magnetics must carry the 1000BASE-T
1. Competitor Product Overview (Bothhand Enterprise Inc.) For PC Card, CardBus, and compact 10/100M Ethernet interface designs, Bothhand NS0013 LF uses a 16-pin
Compares VOOHU WHSG48002PG with Pulse HXB6014HLT for dual-port Gigabit PoE magnetics, covering inductance, loss, isolation, temperature, PoE conditions, and PCB
For industrial gateways, wireless APs, edge computing terminals and embedded switching equipment, the port number, packaging, PoE boundary, PHY matching and PCB
Industrial port "fine cold, drops hot"? This article shows how temperature changes LAN-transformer OCL/DCR and choke impedance, with a -40 to +85 °C wide-temper
The network port function and EMC have passed, but it is stuck in the final Hi-Pot voltage test? Starting from the isolation nature of Ethernet transformers, VO
Tell us your interface, speed and package requirements. Our FAE team can suggest suitable parts and help check the design.
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