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LTC4267 Generating 5.5V

Hello guys!

I'm doing a project using PoE technology through LTC4267. I did my PCB based on the DevKit 1145B, to generate 5.5V to a class 3 device (up to 13W). I have tested the circuit (attached in this message), and it works, the circuit is generating the right voltage to supply my load, but sometimes the circuit have an instability and than my circuit is reseted without an extra load or modification.

Could you plase review my schematic to verify some problem or mistake would I did, or give some recomendation based on my PCB?

Thank you!

OBS: With this configuration I'm having some following values in the circuit.

     PVCC = 7.63V
     Ith/Run = 1.12V
     Optoisolator Diode Anode = 4.4V
     Shunt Divider Reference = 2.44V

  • Hello,

    Can you confirm what you mean by instability and the circuit resetting without additional load? Does your circuit draw at least 10mA from the input supply? IEEE 802.3 requires that the PD draw 10mA for a certain period of time, known as the Maintain Power Signature. Otherwise, the upstream PSE may act as if the cable was disconnected and turn off the port.

    Best Regards,