MP8004 PoE Connection

DC-DC Power Converters
1

I am trying to verify my PoE PD design which was based on the EV8004-QW-00A. What I found is that with 3 different COTS active PoE injectors the circuit does not come up. When using the Ubiquity GP-H480-050G passive injector it works as expected.

I went back and tested the EV8004-QW-00A board with the active injectors and it does not work either. It oscillates by pulsing on for about 800ms then decays down and repeats every ~6sec.

All of the injectors do work with a different PM8803 design.

Are there any known issues with or errata for the EV8004 design? What would cause it to drop out after the Detect and Classify phases?

2

POE needs a minimum load. to avoid a disconnect. I would try putting 100mA of load on the secondary and see what happesn.