LTC4267-3 PoE - another one bites the dust - URGENT

Maybe someone else finds the flaw in my design?

Hi LCE,

What exactly failed in your design? Did it recover after changing the LTC4267-3? I only briefly looked at your schematic but 33 Ohms is a bit high for the primary gate resistor, it could overstress the MOSFET.

Best Regards,

Eric

Hello Eric,

thanks for your reply - and I think this was exactly the problem!

After the PoE started working at all, I checked the output voltage and found too much switching noise.
That's why I increased the gate resistor to 33R, completely forgetting about higher switching losses at the MOSEFET...

I'm still waiting for replacement parts, then I'll come back if this was actually the solution.

Best regards,
LCE

I changed the LTC4267 and the MOSFET, still not working.

Some part is getting really hot, really quick, can't say which component, although I've checked each passive.