LTC4269-1 POE Not Negotiating

I have a new LTC4269-1 based on the DC1335B-B eval kit schematic with a 5V output. It works with the AUX input connected but not with POE. It appears that it is not negotiating.

I am questioning whether I have the RJ45 wired wrong.

Here are schematics.

5-2337993-2 Circuit Diagram

  • Hello,

    It does not look like your RJ45 with integrated magnetics is designed for PoE. If the PSE is connected to the spare pairs, 4-5 and 7-8, then it might work. Otherwise, there is no DC path to the PD. You'll need access the transformer center taps on the cable side, and the transformer should be rated for the expected PoE current. Please look at the example from one of our ADI demo boards.

    Best Regards,

    Eric