Power over Ethernet (POE) is a technology that enables LAN/network cable to carry the electrical power. This solves the challenge of messy or bulky wiring. POE injector helps add power to the ethernet cable.
At the input side external power adapter which is AC to 48V DC is connected and Ethernet cable is connector and on the other side you get the POE enabled Ethernet.
The design entirely around external power adapter and onboard Monolithic Power MP3924 based circuit.
The MP3924 is a quad-port, IEEE 802.3af/at compliant, power sourcing equipment (PSE) controller for power over Ethernet (PoE) applications.
On the PCB a coupling transfer is used in-between the input and output LAN connector to inject the power.
In the past few years I have built a couple of products which had POE ethernet and power was extracted directly from the Ethernet connector to power the whole board. Some designs had another option to power the board but some where having POE as the only option.
It was interesting to see POE injector side of things. Now I know how it work, from source to sink.
I hope you found this teardown useful and learned something new today!
You can watch this video to understand more about POE.
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I am currently working as an embedded systems design consultant and helping companies build custom embedded products, develop test automation solution for their PCB or complete product.
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