We are using the SI3404 chip to use POE, When we used the standard PoE injectors, it works perfectly.
But when we used the non-standard PoE injectors, the chip would burn out occasionally.
Our design is a reference of Si3404-Buck EVB board. Is the SI3404 not support the non-standard PoE injectors ?
Thank you for your Help.
Hi LaoSheng Lin,
the non standard PoE injector can damage the circuit. To protect the circuit you can install a 2 ohm resistor in series with C8.
Thanks and regards,
Can you please explain how the failure occurs with non-standard POE injectors and what the 2ohm resistor in series with C8 does? I understood that the Si3404 had built-in in-rush limiting so wouldn't need series resistors. Also, if needed I would have thought that they would go in series with the VPOS/VNEG lines rather than the CDET cap.
Hii Laosheng Lin
Power-over-Ethernet specs have changed over the years — PoE devices have gotten more powerful, and so Ethernet cables are starting to become more like a power line. Silicon Labs’ John Wilson recently did a short video with us about four new power device ICs built with higher PoE power levels in mind. John reviewed demonstrations that range from the SI3404, a 15-W PoE PD chip, and a highly efficient SI34061, a 30-W capable, highly efficient power device. All of these products says Wilson, are bringing new levels of efficiency and of integration.
Thanks for the information, it helps a lot
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